Disability and Rehabilitation: Assistive Technology
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Public transit bus ramp slopes measured in situ Gina Bertocci, Karen Frost & Craig Smalley To cite this article: Gina Bertocci, Karen Frost & Craig Smalley (2014): Public transit bus ramp slopes measured in situ, Disability and Rehabilitation: Assistive Technology To link to this article: http://dx.doi.org/10.3109/17483107.2014.913714
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Date: 13 November 2015, At: 21:15
http://informahealthcare.com/idt ISSN 1748-3107 print/ISSN 1748-3115 online Disabil Rehabil Assist Technol, Early Online: 1–6 ! 2014 Informa UK Ltd. DOI: 10.3109/17483107.2014.913714
RESEARCH PAPER
Public transit bus ramp slopes measured in situ Gina Bertocci, Karen Frost, and Craig Smalley
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Bioengineering Department, University of Louisville, Louisville, KY, USA
Abstract
Keywords
Purpose: The slopes of fixed-route bus ramps deployed for wheeled mobility device (WhMD) users during boarding and alighting were assessed. Measured slopes were compared to the proposed Americans with Disabilities Act (ADA) maximum allowable ramp slope. Methods: A ramp-embedded inclinometer measured ramp slope during WhMD user boarding and alighting on a fixed-route transit bus. The extent of bus kneeling was determined for each ramp deployment. In-vehicle video surveillance cameras captured ramp deployment level (street versus sidewalk) and WhMD type. Results: Ramp slopes ranged from 4 to 15.5 with means of 4.3 during boarding (n ¼ 406) and 4.2 during alighting (n ¼ 405). Ramp slope was significantly greater when deployed to street level. During boarding, the proposed ADA maximum allowable ramp slope (9.5 ) was exceeded in 66.7% of instances when the ramp was deployed to street level, and in 1.9% of instances when the ramp was deployed to sidewalk level. During alighting, the proposed ADA maximum allowable slope was exceeded in 56.8% of instances when the ramp was deployed to street level and in 1.4% of instances when the ramp was deployed to sidewalk level. Conclusions: Deployment level, built environment and extent of bus kneeling can affect slope of ramps ascended/descended by WhMD users when accessing transit buses.
Accessibility, Americans with Disabilities Act, transportation, wheelchair History Received 13 November 2013 Revised 7 April 2014 Accepted 7 April 2014 Published online 2 May 2014
ä Implications for Rehabilitation
Since public transportation services are critical for integration of wheeled mobility device (WhMD) users into the community and society, it is important that they, as well as their therapists, are aware of conditions that may be encountered when accessing transit buses. Knowledge of real world ramp slope conditions that may be encountered when accessing transit buses will allow therapists to better access capabilities of WhMD users in a controlled clinical setting. Real world ramp slope conditions can be recreated in a clinical setting to allow WhMD users to develop and practice necessary skills to safely navigate this environment. Knowing that extent of bus kneeling and ramp deployment level can influence ramp slope, therapists can educate WhMD users to request bus operators further kneel the bus floor and/ or redeploy the ramp to a sidewalk level when appropriate, so that the least practicable slope will be presented for ingress/egress.
Introduction Background Nationwide, an estimated 2.7 million adults are wheelchair or scooter (collectively, wheeled mobility device or ‘‘WhMD’’) users [1], and this number is expected to increase with the aging population. WhMD users must often rely upon public transportation to access work, medical care, school and social activities. In 1990, the Americans with Disabilities Act (ADA) prohibited discrimination against people with disabilities in employment practices, public accommodations and telecommunication
Address for correspondence: Gina Bertocci, PhD, PE, Bioengineering Department, University of Louisville, Rm. 204 – Health Sciences Research Tower, 500 S. Preston St., Louisville, KY 40202, USA. Tel: 502-852-0296. E-mail: [email protected]
services [2], and required that public transit providers accommodate persons who remain seated in their WhMD when accessing and using public transportation. Despite ADA legislation, numerous studies continue to identify the lack of accessible transportation as a barrier to full integration and participation in society for people with disabilities, particularly WhMD users [3–6]. The National Institute for Disability and Rehabilitation Research (NIDRR) reported that over a third of WhMD users encounter problems while attempting to physically access public transportation [2]. Public transit buses are the most common form of public transportation across the US. Deployable ramps installed on public transit buses are often the primary means enabling WhMD user access to public transit buses. Frost et al. [7] conducted a retrospective review of six years of WhMD-related adverse incident reports maintained by a metropolitan transit agency and found that WhMD users experienced a
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Table 1. ADA ramp slope specifications – buses and vans . Maximum allowable ramp slope Ramp deployment level Ground Vehicle Vehicle Vehicle Vehicle
[street] level floor 3 in above 6-inch curb floor 43 in and 6 in above 6-inch curb floor 46 in and 9 in above 6-inch curb floor 49 in above 6-inch curb
(Ratio)
(Degrees)
1:4 1:4 1:6 1:8 1:12
14.0 14.0 9.5 7.1 4.8
a
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ADA accessibility specifications for transportation vehicles, subpart b-buses, vans and systems.
greater percentage of incidents when using the bus ramp (42.6%) than during transit (33.9%) and 43.6% of ramp-related incidents resulted in injury. The authors subsequently conducted an observational study using video surveillance footage to assess difficulties and incidents encountered by WhMD users when accessing and traveling on public transit buses [8]. Steep ramp slopes appeared to be associated with 27.5% of ramp-related difficulties and incidents. The existing ADA Accessibility Specifications for Transportation Vehicles [9] (Table 1), state that ramps ‘‘shall have the least slope practicable’’. However, as currently written it is difficult, if not impossible, for bus operators to assure compliance with ramp slope requirements given variations in the built environment (e.g. curb height and presence or absence of curbs), and the extent of vehicle kneeling implemented by the bus operator. In 2010, the US Access Board announced a Notice of Proposed Rule Making (NPRM) to revise and update Accessibility Guidelines for buses, over-the-road buses and vans. The Access Board proposed reducing the maximum ramp slope to 9.5 (1:6) when deployed to boarding/alighting areas ‘‘without station platforms and to the roadway’’ [10]. To-date, no changes to the 1990 Accessibility Guidelines have been implemented. The authors previously measured ramp slope on a single public transit bus (Gillig, Hayward, CA, 2008 model, low-floor public transit bus) to determine ramp slope during full kneeling and minimal kneeling conditions when deployed to street and sidewalk level (15.2 cm (6 in) curb). Under minimally kneeled conditions, ramp slope measured 10 when deployed to sidewalk level and 17 when deployed to street level, exceeding both the current and proposed ADA ramp slope guidelines [7]. These findings indicate that ramp slopes currently encountered by WhMD users when boarding or alighting from public transit buses may exceed the proposed ADA maximum ramp slope of 9.5 (1:6). Purpose In this study, we sought to describe in situ deployed ramp slopes encountered by WhMD-using passengers during boarding and alighting a public transit bus servicing a metropolitan region, and to compare measured slopes to the proposed ADA NPRM maximum allowable ramp slope. Additionally, we assessed the extent that the bus was kneeled by the operator prior to ramp deployment, and the influence of kneeling on resulting ramp slope.
Methods Subjects This study was conducted in accordance with IRB protocol #12.0098. The study population consisted of WhMD-seated
passengers boarding and alighting a public transit bus equipped with an instrumented ramp. Transit buses, including the bus used in this study, are randomly assigned on a daily basis to both operators and routes throughout the service region. The specially instrumented bus was amongst those randomly assigned. The service region includes urban and suburban environments with varying street and sidewalk conditions. Instrumentation A single, low floor public transit bus (2010 model year GilligÕ 40 ft. bus) equipped with a Lift-U Fold-Out Plus ramp (Model LU11; Escalon, CA) was used for this study. Boarding and alighting activities were recorded using an AngelTraxÕ MiniMicro 2-camera system (Newton, AL). One camera was mounted above the bus operator’s seat near the ceiling and provided a 73.3 field of view that included the front interior portion of the bus and approximately 3 m beyond the deployed ramp. A second camera was mounted beneath the operator’s elevated seat platform and provided an 81.2 field of view that included a WhMD-level view of the ramp and same interior area of the bus. Together, these two cameras provided views of the external terrain, deployment level and WhMD type. Video image resolution was 720 584, and frame rate was 30 frames per second (FPS), yielding 15 FPS for each of the two cameras. Signs were posted in each bus notifying passengers that activities are being monitored and recorded for public safety. Ramp slope was measured using an analog inclinometer (VTI, SCA121T-D05, Vantaa, Finland) securely mounted within the ramp structure. The ramp inclinometer was calibrated upon installation to convert the output voltage to a corresponding ramp angle. Inclinometer calibration was verified every two months. The inclinometer provided a ±90 measuring range with 0.0035 resolution. Inclinometer output was recorded at 1 Hz using a data logger (Omega OM-CP-VOLT101A-15V, Stamford, CT). The data logger was positioned to provide easy access for periodic download of recorded data. Video files and data logger recordings were time-stamped, allowing for synchronization. Audible feedback in the form of discrete repeating signals was provided to the bus operator when the switch to kneel the bus floor was activated. Extent of bus kneeling was determined by calibrating the number of discrete audible signals to the percent of full kneeling across the possible range. The number of discrete audible signals was determined for each ramp deployment using the video camera audio recording capability. Twelve discrete audible signals equated to full kneeling. Extent of kneeling was recorded in the database as percentage of full kneeling (e.g. six discrete signals equated to 50% kneel). An interlock control prevents ramp deployment without engaging the switch to kneel the bus; one discrete signal yielded the minimum possible kneeling. Bus floor height was found to decrease from 39.4 cm to 30.5 cm when fully kneeled compared to minimally kneeled. This equated to a 5.2 reduction in ramp slope from minimal kneel to full kneel when deployed to flat level ground. Procedure Ramp slope and video data were collected over a 15-month sequential period. Video recordings and inclinometer data were retrieved every 7–10 days for analysis. A FileMaker Pro database (Ver. 12, Santa Clara, CA) was used to abstract video and ramp slope data for WhMD-passenger boarding and alighting events. Data collection included recording WhMD type and drive wheel position, ramp deployment level (street, sidewalk), percent (extent) of bus kneeling (i.e. 100% equates to full kneeling) and ramp slope.
Public transit bus ramp slopes measured in situ
DOI: 10.3109/17483107.2014.913714
Data analysis Descriptive statistics were used to describe ramp slope means and standard deviations, along with frequency distributions. Statistical analysis was performed using SPSS (Ver. 21, IBM, Armonk, NY) to determine if deployed ramp slopes and extent of bus kneeling differed based on boarding versus alighting activity, WhMD types and deployment level (street versus sidewalk). Normally distributed data were analyzed using ANOVA; data failing to meet assumptions of normality were analyzed using Mann–Whitney Utest. Kruskal–Wallis ANOVA was used to examine differences in ramp deployment conditions across WhMD type. Determination of significance was established at p 0.05. Pearson’s correlation was used to evaluate the relationship between extent of bus kneeling and deployed ramp slope.
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Results
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public transit vehicles and averages between 10 400–13 000 annual WhMD trips. The geographic region sits on a wide, flat flood plane with gently rolling hills. Four hundred seven WhMD-seated passengers were observed boarding and alighting the bus. (One WhMD-seated passenger boarded without ramp deployment, one alighted without ramp deployment and one WhMD-seated passenger alighting process was not captured on video leading to slight differences in sample size reported in the figures.) Observations included 303 power wheelchairs (74.5%), 68 manual wheelchairs (16.7%), 33 scooters (8.1%) and three attendant-propelled adult strollers (0.74%). Among power wheelchairs, 125 were front wheel drive (41.3%), 148 were mid wheel drive (48.8%) and 30 were rear wheel drive (9.9%). In two cases only boarding was captured and in one case only alighting was captured.
Overview
Ramp slope measurements across boarding and alighting activities
The transit bus used in this study is operated by a public metropolitan transit agency serving a population of approximately 1.3 million. The transit agency operates 240 large, accessible,
Frequency distributions of measured ramp slopes during both boarding and alighting were slightly skewed towards steeper ramp slopes (Figures 1 and 2).
Figure 1. Frequency distribution of observed ramp slopes during boarding (n ¼ 406).
Figure 2. Frequency distribution of observed ramp slopes during alighting (n ¼ 405).
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As might be expected based on frequency distributions, there was no significant difference in mean ramp slope between boarding and alighting activities (p ¼ 0.497) (Table 2). Nor were there significant differences in mean ramp slope between boarding (p ¼ 0.865) and alighting (p ¼ 0.153) based on WhMD type (due to small sample size, attendant-propelled strollers were not included this analysis).
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Ramp slope based on deployment level Ramp slope can be expected to differ based on the built environment (e.g. curbs, curb cuts). We compared mean ramp slope during boarding and alighting activities based on ramp deployment level (street versus sidewalk). The ramp was more often deployed to sidewalk level versus street level during boarding and alighting activities (92.0 and 90.8%, respectively). However, mean ramp slope was approximately 7o greater when the ramp was deployed to street versus sidewalk level; this difference was statistically significant (p ¼ 0.000) (Table 3). Additionally, when deployed to street level, more than half of ramp slopes exceeded the proposed ADA guideline for maximum ramp slope (9.5o) during both boarding and alighting (Table 4). Relationship between bus kneeling and ramp slope The bus was kneeled 50% or greater during the majority of ramp deployments; however, during boarding, the mean percentage of bus kneeling was greater (73.1% ± 21.6%) than during alighting (68.4% ± 23.6%), and this difference was statistically significant (p ¼ 0.014). Additionally, although the ramp was more often deployed to sidewalk level during boarding and alighting activities, findings showed a significant difference between mean percentage of bus kneeling when the ramp was deployed to street level versus sidewalk level. When kneeled to street level, the mean percentage of bus kneeling was 83.6% ± 16.2%,
Table 2. Mean ramp slopes for boarding and alightinga.
WhMD type
Boarding – Mean ramp slope (deg ± SD) 4.3 4.3 4.5 4.3
All Manual Power Scooter
Alighting – Mean ramp slope (deg ± SD)
(±2.9 ) (±2.9 ) (±2.8 ) (±2.7 )
4.2 4.0 4.1 5.1
(±3.1 ) (±2.6 ) (±3.0 ) (±3.5 )
a
Ramp slopes for three strollers were 1 , 3.5 and 10.5 in boarding and 15 , 9 and 9.5 in alighting.
Table 3. Ramp slope based upon deployment level. Ramp slope in boarding
Ramp slope in alighting
Street level Sidewalk level Street level Sidewalk level (n ¼ 33) (n ¼ 373) (n ¼ 37) (n ¼ 368) Mean (±SD) 10.6 (±2.5) Maximum 15.5
3.8 (±2.1) 11.5
10.2 (±2.1) 15
3.6 (±2.4) 13.5
Table 4. Percent deployments exceeding proposed maximum allowable ADA allowable ramp slopea based upon deployment level.
Boarding (n ¼ 406) Alighting (n ¼ 405) a
Sidewalk level
Street level
1.9% 1.4%
66.7% 56.8%
Proposed ADA maximum ramp slope ¼ 9.5 (1:6).
compared to 69.5% ± 22.9% during sidewalk level boardings/ alightings (p50.01). Full kneeling occurred during 17.8% of boardings/alightings. Operators fully kneeled the bus almost twice as often during street level boardings/alightings (30.4%) compared to sidewalk level boardings/alightings (16.6%). Interestingly, the percentage of bus kneeling was not correlated to ramp slope (r ¼ 0.054) (Figure 3). Nor was there a significant difference (p ¼ 0.106) in the mean percentage of bus kneeling across WhMD types. We also examined the percentage of bus kneeling for the subset of ramp deployments that exceeded the proposed ADA maximum ramp slope of 9.5 (n ¼ 54). The mean percentage of bus kneeling within this subset was 81.0% (±19.6%).
Discussion Over half of ramp deployments to street level exceeded the proposed ADA maximum allowable ramp slope (9.5 or 1:6). This finding suggests that transit agencies may have difficulty complying with the proposed ramp slope changes to the ADA Accessibility Guidelines for Transportation Vehicles when ramps must be deployed to street level. We measured achievable ramp slopes of the bus used in this study under full kneeling conditions when the ramp was deployed to both street and sidewalk level (level surface, no cross slopes). When fully kneeled and deployed to street level, the achievable ramp slope was 9.5 . When fully kneeled and deployed to a sidewalk with a 15.2 cm (6 in) curb, the achievable ramp slope was 2 . Ramp and bus design, as well as the built environment, can influence the minimum achievable ramp slope. The bus used in this study was equipped with an interlock control that prevented ramp deployment without activation of bus kneeling, but the bus operator controlled the percentage of kneeling. This interlocking control is not required by ADA; it is a vehicle manufacturer option that is specified by individual transit agencies during the vehicle procurement process. In some instances where steep ramp slopes were measured (maximum of 15.5 ), we observed exterior terrain that sloped away from the bus, so that the distal end of the ramp interfaced with the exterior surface at an elevation below street level. Thus, when deploying to street level with terrain sloping away from the bus, the proposed maximum allowable slope could be exceeded despite full kneeling of the bus floor. Conversely, when deployed to a high sidewalk curb with upward sloping terrain, it was possible for the distal end of the ramp to be higher than the proximal interior end, resulting in a negative slope. Additionally, sidewalk deployments were not always to a typical 6" (14.7 cm) curb. Although we were not able to measure curb height, we observed sidewalk curbs at elevations only slightly above the street level. These conditions may contribute to steep ramp slopes during sidewalk deployments despite a high extent of kneeling initiated by the bus operator. Cross-sloping streets and sidewalks, and the distance between the stopped bus and sidewalk can also affect ramp slope. Sidewalks typically slope towards the street to promote drainage. A ramp deployed from a bus located in close proximity to the sidewalk will result in the distal end of the ramp resting on the sidewalk at a higher elevation compared to a ramp deployed from a bus located farther from the sidewalk (Figure 4). Thus, a lesser slope can often be achieved when the bus stops in closer proximity to the curb. ADA Guidelines specify a maximum cross slope of 1.19 (1:48) for sidewalks [11]. However, measurement of streets and sidewalks in the transit area where our study was conducted revealed cross slopes up to 2.3 on streets and 2.2 on sidewalks. When deploying a 1.22 m ramp (the length of the ramp used in this study) under cross-sloping street and sidewalk
Public transit bus ramp slopes measured in situ
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DOI: 10.3109/17483107.2014.913714
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Figure 3. Percentage of full kneel versus ramp slope (n ¼ 799).
Figure 4. Bus stopped on cross-sloping street deploying the ramp to a cross-sloping sidewalk.
conditions, a 1 m change in bus to sidewalk distance can translate to as much as a 3.7 difference in ramp slope. Excessively steep ramp slopes and negative slopes may, in some cases, be improved or resolved by bus operator actions. We observed one operator advising a WhMD user to move from the street to a sidewalk to minimize ramp slope and making it easier and safer to ascend the ramp. However, in other cases, operators were observed deploying the ramp to street level when a curbed sidewalk was available nearby. Partial kneeling contributed to overly steep ramp angles in some cases, while excessive kneeling, when deploying to sidewalks with high curbs contributed to negative ramp slopes. Negative slopes can present challenges during ramp use for mid-wheel drive power WhMDs by causing drive wheels to lose contact with the ramp surface as the front and rear casters ‘‘bridge’’ across the ramp and bus floor. Given the lack of significant difference in deployed ramp slope across WhMD types, it would appear that vehicle operators were not influenced in their deployment behaviors based upon whether a WhMD user was able to traverse the ramp using electric power or through self-propulsion. The lack of correlation between percentage of bus kneeling and ramp slope may be partially explained by operator choice of deployment location, cross-sloping deployment surfacesand variations in sidewalk curb heights. Differences in the percentage of bus kneeling between street and sidewalk level ramp deployments suggests that bus operators tend to kneel the bus more when anticipating a steep ramp slope (i.e. deployment to street level). Similarly, when the bus was kneeled only slightly, high curbs were often observed during ramp deployment. The majority of ramp deployments occurred when the bus was kneeled 50% or greater. However, full kneeling can reduce ramp slope by up to 5.2 , while a change from 50% kneeling to full kneeling can reduce ramp
slope up to 2.6 . Given observed ramp slopes ranging from 4 to 15.5 in this study, it is clear that a combination of factors, including kneeling, can affect ramp slope. In cases where ramp slope exceeded the proposed ADA maximum ramp slope, we observed that some operators stopped short of full kneeling. While the majority of these scenarios occurred when the ramp was deployed to street level, some instances occurred when the ramp was deployed to the sidewalk level (Figure 3). Conversely, during some deployments, the proposed ADA maximum allowable ramp slope was exceeded despite the bus operator fully kneeling the bus (Figure 3); this occurred in deployments to both street and sidewalk levels. This scenario points to conditions of the built environment preventing the operator from achieving a more accessible ramp slope. When considering the proposed the ADA maximum ramp slope 9.5 (1:6) it is of interest to compare slopes of a WhMD user may encounter when navigating the built environment. ADA Accessible Routes Guidelines Section 405.1 [12] states that ramps along accessible routes shall have a running slope not steeper than 1:12 or 4.8 . Consequently, WhMD users capable of navigating the built environment may be presented with an ADA-compliant ramp slope that is twice as steep when boarding or alighting from a transit vehicle. Clearly this inconsistency between existing and proposed ADA Guidelines can introduce challenges or barriers to independent and safe access. The inherent stability of a WhMD when ascending/descending a ramp is also of interest given that instability can contribute to WhMD tipping and associated user injuries [13]. RESNA Wheelchair Standards [14] evaluate dynamic stability of power WhMDs ascending and descending inclined planes having a slope of 0 , 3 , 6 and 10 when occupied with a 100 kg surrogate. During testing, a score of 0 to 4 is assigned to a WhMD based upon the number of wheels remaining in contact with the inclined surface and whether or not tipping occurred (4 ¼ one uphill wheel remains in contact with surface; 0 ¼ WhMD tipped over). When evaluating dynamic stability, Rentschler et al. [15] found that none of the power WhMDs tested maintained all wheels in contact with a 10 inclined surface. These findings suggest that ascending or descending a ramp slope of 10 , only 0.5 steeper than the proposed maximum allowable ADA ramp slope for accessing transit vehicles, could lead to WhMD instability. The Centers for Medicare and Medicaid Services (CMS) require that power WhMDs be tested and proven to be stable on inclined slopes of either 6 , 7.5 or 9 , depending upon WhMD classification (i.e. Group 1 through Group 5) [16]. Thus,
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Medicare or Medicaid-reimbursed power WhMDs are not required to maintain stability on slopes as steep as the ADA proposed maximum allowable ramp slope of 9.5 . In other words, power WhMDs covered by Medicare or Medicaid are not required to be dynamically stable on ADA-compliant slopes that a WhMD user may encounter when accessing a transit vehicle. This incompatibility between proposed ADA Transportation Vehicle Guidelines and existing ADA Guidelines for Accessible Routes and CMS power WhMD stability testing criteria may lead to a loss of independence when accessing transportation vehicles or even place WhMD users at an increased risk for injury when traversing vehicle ramps. Findings from our study suggest that compliance with the proposed ADA maximum ramp slope may not be achievable given existing vehicle and ramp designs, and varying conditions of the built environment. Training focused on providing an improved understanding by bus operators of factors contributing to increased ramp slope would benefit WhMD user access to public transit buses. Transit agency policies, such as not deploying to street level (when possible), should be implemented to reinforce best operator practices. Incorporating inclinometers within ramps, combined with real time feedback and alert systems could be useful to signal vehicle operators and WhMD users when ramp slope exceeds a threshold or is too steep for independent or safe access. Improvements in vehicle and ramp manufacturer design guidelines, as well as bus stop designs, that anticipate their effects on ramp deployment are also needed. For example, requiring control interlocks that prevent ramp deployment without bus kneeling should be compulsory. Similarly, comprehensive assessments of bus stop built environments by transit agencies to assure appropriately elevated surfaces above street level are present to receive deployed ramps are also warranted. Limitations Findings were based on observations of a single vehicle model and manufacturer and a single ramp design. Varying ramp and vehicle designs, as well as varying geographical regions, may result in different ramp slopes encountered by WhMD users. Additionally, bus operator practices may vary across transit agencies. Thus, these findings are not generalizable across transit agencies throughout the US. Additionally, we were unable to assess conditions of the built environment where ramp deployments occurred, and thus were not able to specifically describe built environment-related factors (e.g. sidewalk curb elevation relative to street, sidewalk and street cross-slopes) for each deployment that may have contributed to the inability to achieve the least practicable ramp slope. Similarly, we were unable to determine proximity of the bus to the sidewalk curb for each deployment.
Conclusion This study utilized a ramp-embedded inclinometer in conjunction with videography on a large accessible, low floor transit bus to characterize ramp slope when deployed for WhMD user boarding and alighting. Over half of ramp deployments to street level in boarding and alighting exceeded the proposed ADA maximum allowable ramp slope of 9.5 . Ramp deployments to sidewalk level exceeded 9.5 in less than 2% of deployments. Deployment level (street versus sidewalk) and the built environment, specifically sidewalk and street cross slopes, as well as sidewalk curb height, can have a substantial effect on ramp slope. Bus operator controlled factors such as extent of bus kneeling and ramp
Disabil Rehabil Assist Technol, Early Online: 1–6
deployment location can influence ramp slope. Although operators deployed the ramp to sidewalk level in most cases of boarding and alighting, they tended to kneel the bus to a greater extent for WhMD user boarding than alighting. Operator education conveying the influence of their actions on ramp slope during WhMD user boarding and alighting should be emphasized in transit agency training programs. Additionally, urban planners should anticipate the effects of the bus stop built environment and terrain on ramp deployment.
Declaration of interest This study was funded by the National Institute on Disability and Rehabilitation Research (NIDRR), Field Initiated Projects program, Grant #H133G110074. The opinions expressed herein are those of the authors and do not necessarily reflect NIDRR opinions. The authors have no other declarations of interest to report.
References 1. LaPlante M, Kaye HM. Demographics and trends in wheeled mobility equipment use and accessibility in the community. Assist Technol 2010;22:3–17. 2. Americans with Disabilities Act of 1990, Pub. L. No. 101–336. 104 Stat. 328;1990. 3. Kaye HM, Laplante M. Mobility device use in the United States. Washington, DC: Department of Education; 2000. 4. National Council on Disability. The current state of transportation for people with disabilities. Washington, DC: National Council on Disability; 2005. 5. Buning ME, Getchell CA, Bertocci GE, Fitzgerald SG. Riding a bus while seated in a wheelchair: a pilot study of attitudes and behavior regarding safety practices. Assist Technol 2007;19:166–79. 6. Easter Seals Project Action. Status report on the use of wheelchairs and other mobility devices on public and private transportation. Washington, DC: Easter Seals Project Action; 2008. 7. Frost KL, Bertocci G. Retrospective review of adverse incidents involving passengers seated in wheeled mobility devices while traveling in large accessible transit vehicles. Med Eng Phys 2010;32: 230–6. 8. Frost KL, Bertocci G, Sison S. Ingress/egress incidents involving wheelchair users in a fixed-route public transit environment. J Public Transport 2010;13:41–62. 9. Architectural and Transportation Barriers Compliance Board. ADA Accessibility Guidelines (ADAAG) for Transportation Vehicles. 36 CFR Part 1192; 1998. 10. Architectural and Transportation Barriers Compliance Board. Americans with Disabilities Act (ADA) accessibility guidelines for transportation vehicles. NPRM 75 FR 43748; 2010. 11. Department of Justice, 2010 ADA Standards for Accessible Design, Sept. 15, 2010. 12. Architectural and Transportation Barriers Compliance Board. Americans with Disabilities Act (ADA) Accessibility Guidelines for Accessible Routes – Ramps Section 405.1; 2004. 13. Calder C, Kirby R. Fatal wheelchair-related accidents in the United States. Am J Phys Med Rehabil 1990;69:184–90. 14. Rehabilitation Engineering Society of North America (RESNA). RESNA WC-2:2009 American National Standard for Wheelchairs Vol. 2: Additional Requirements for Wheelchairs (including Scooters) with Electrical Systems. Arlington (VA): RESNA; 2009. 15. Rentschler A, Cooper R, Fitzgerald S, et al. Evaluation of selected electric powered wheelchairs using the ANSI/RESNA Standards. Arch Phys Med Rehabil 2004;85:611–19. 16. Centers for Medicare and Medicaid Services, Technical Expert Panel Report – Power Mobility Device Coding Guidelines. August 2006. Available from: https://www.dmepdac.com/resources/articles/ 2006/08_14_06.pdf [last accessed 7 Apr 2014].
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Public transit bus ramp slopes measured in situ Gina Bertocci, Karen Frost & Craig Smalley To cite this article: Gina Bertocci, Karen Frost & Craig Smalley (2014): Public transit bus ramp slopes measured in situ, Disability and Rehabilitation: Assistive Technology To link to this article: http://dx.doi.org/10.3109/17483107.2014.913714
Published online: 02 May 2014.
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Date: 13 November 2015, At: 21:15
http://informahealthcare.com/idt ISSN 1748-3107 print/ISSN 1748-3115 online Disabil Rehabil Assist Technol, Early Online: 1–6 ! 2014 Informa UK Ltd. DOI: 10.3109/17483107.2014.913714
RESEARCH PAPER
Public transit bus ramp slopes measured in situ Gina Bertocci, Karen Frost, and Craig Smalley
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Bioengineering Department, University of Louisville, Louisville, KY, USA
Abstract
Keywords
Purpose: The slopes of fixed-route bus ramps deployed for wheeled mobility device (WhMD) users during boarding and alighting were assessed. Measured slopes were compared to the proposed Americans with Disabilities Act (ADA) maximum allowable ramp slope. Methods: A ramp-embedded inclinometer measured ramp slope during WhMD user boarding and alighting on a fixed-route transit bus. The extent of bus kneeling was determined for each ramp deployment. In-vehicle video surveillance cameras captured ramp deployment level (street versus sidewalk) and WhMD type. Results: Ramp slopes ranged from 4 to 15.5 with means of 4.3 during boarding (n ¼ 406) and 4.2 during alighting (n ¼ 405). Ramp slope was significantly greater when deployed to street level. During boarding, the proposed ADA maximum allowable ramp slope (9.5 ) was exceeded in 66.7% of instances when the ramp was deployed to street level, and in 1.9% of instances when the ramp was deployed to sidewalk level. During alighting, the proposed ADA maximum allowable slope was exceeded in 56.8% of instances when the ramp was deployed to street level and in 1.4% of instances when the ramp was deployed to sidewalk level. Conclusions: Deployment level, built environment and extent of bus kneeling can affect slope of ramps ascended/descended by WhMD users when accessing transit buses.
Accessibility, Americans with Disabilities Act, transportation, wheelchair History Received 13 November 2013 Revised 7 April 2014 Accepted 7 April 2014 Published online 2 May 2014
ä Implications for Rehabilitation
Since public transportation services are critical for integration of wheeled mobility device (WhMD) users into the community and society, it is important that they, as well as their therapists, are aware of conditions that may be encountered when accessing transit buses. Knowledge of real world ramp slope conditions that may be encountered when accessing transit buses will allow therapists to better access capabilities of WhMD users in a controlled clinical setting. Real world ramp slope conditions can be recreated in a clinical setting to allow WhMD users to develop and practice necessary skills to safely navigate this environment. Knowing that extent of bus kneeling and ramp deployment level can influence ramp slope, therapists can educate WhMD users to request bus operators further kneel the bus floor and/ or redeploy the ramp to a sidewalk level when appropriate, so that the least practicable slope will be presented for ingress/egress.
Introduction Background Nationwide, an estimated 2.7 million adults are wheelchair or scooter (collectively, wheeled mobility device or ‘‘WhMD’’) users [1], and this number is expected to increase with the aging population. WhMD users must often rely upon public transportation to access work, medical care, school and social activities. In 1990, the Americans with Disabilities Act (ADA) prohibited discrimination against people with disabilities in employment practices, public accommodations and telecommunication
Address for correspondence: Gina Bertocci, PhD, PE, Bioengineering Department, University of Louisville, Rm. 204 – Health Sciences Research Tower, 500 S. Preston St., Louisville, KY 40202, USA. Tel: 502-852-0296. E-mail: [email protected]
services [2], and required that public transit providers accommodate persons who remain seated in their WhMD when accessing and using public transportation. Despite ADA legislation, numerous studies continue to identify the lack of accessible transportation as a barrier to full integration and participation in society for people with disabilities, particularly WhMD users [3–6]. The National Institute for Disability and Rehabilitation Research (NIDRR) reported that over a third of WhMD users encounter problems while attempting to physically access public transportation [2]. Public transit buses are the most common form of public transportation across the US. Deployable ramps installed on public transit buses are often the primary means enabling WhMD user access to public transit buses. Frost et al. [7] conducted a retrospective review of six years of WhMD-related adverse incident reports maintained by a metropolitan transit agency and found that WhMD users experienced a
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Table 1. ADA ramp slope specifications – buses and vans . Maximum allowable ramp slope Ramp deployment level Ground Vehicle Vehicle Vehicle Vehicle
[street] level floor 3 in above 6-inch curb floor 43 in and 6 in above 6-inch curb floor 46 in and 9 in above 6-inch curb floor 49 in above 6-inch curb
(Ratio)
(Degrees)
1:4 1:4 1:6 1:8 1:12
14.0 14.0 9.5 7.1 4.8
a
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ADA accessibility specifications for transportation vehicles, subpart b-buses, vans and systems.
greater percentage of incidents when using the bus ramp (42.6%) than during transit (33.9%) and 43.6% of ramp-related incidents resulted in injury. The authors subsequently conducted an observational study using video surveillance footage to assess difficulties and incidents encountered by WhMD users when accessing and traveling on public transit buses [8]. Steep ramp slopes appeared to be associated with 27.5% of ramp-related difficulties and incidents. The existing ADA Accessibility Specifications for Transportation Vehicles [9] (Table 1), state that ramps ‘‘shall have the least slope practicable’’. However, as currently written it is difficult, if not impossible, for bus operators to assure compliance with ramp slope requirements given variations in the built environment (e.g. curb height and presence or absence of curbs), and the extent of vehicle kneeling implemented by the bus operator. In 2010, the US Access Board announced a Notice of Proposed Rule Making (NPRM) to revise and update Accessibility Guidelines for buses, over-the-road buses and vans. The Access Board proposed reducing the maximum ramp slope to 9.5 (1:6) when deployed to boarding/alighting areas ‘‘without station platforms and to the roadway’’ [10]. To-date, no changes to the 1990 Accessibility Guidelines have been implemented. The authors previously measured ramp slope on a single public transit bus (Gillig, Hayward, CA, 2008 model, low-floor public transit bus) to determine ramp slope during full kneeling and minimal kneeling conditions when deployed to street and sidewalk level (15.2 cm (6 in) curb). Under minimally kneeled conditions, ramp slope measured 10 when deployed to sidewalk level and 17 when deployed to street level, exceeding both the current and proposed ADA ramp slope guidelines [7]. These findings indicate that ramp slopes currently encountered by WhMD users when boarding or alighting from public transit buses may exceed the proposed ADA maximum ramp slope of 9.5 (1:6). Purpose In this study, we sought to describe in situ deployed ramp slopes encountered by WhMD-using passengers during boarding and alighting a public transit bus servicing a metropolitan region, and to compare measured slopes to the proposed ADA NPRM maximum allowable ramp slope. Additionally, we assessed the extent that the bus was kneeled by the operator prior to ramp deployment, and the influence of kneeling on resulting ramp slope.
Methods Subjects This study was conducted in accordance with IRB protocol #12.0098. The study population consisted of WhMD-seated
passengers boarding and alighting a public transit bus equipped with an instrumented ramp. Transit buses, including the bus used in this study, are randomly assigned on a daily basis to both operators and routes throughout the service region. The specially instrumented bus was amongst those randomly assigned. The service region includes urban and suburban environments with varying street and sidewalk conditions. Instrumentation A single, low floor public transit bus (2010 model year GilligÕ 40 ft. bus) equipped with a Lift-U Fold-Out Plus ramp (Model LU11; Escalon, CA) was used for this study. Boarding and alighting activities were recorded using an AngelTraxÕ MiniMicro 2-camera system (Newton, AL). One camera was mounted above the bus operator’s seat near the ceiling and provided a 73.3 field of view that included the front interior portion of the bus and approximately 3 m beyond the deployed ramp. A second camera was mounted beneath the operator’s elevated seat platform and provided an 81.2 field of view that included a WhMD-level view of the ramp and same interior area of the bus. Together, these two cameras provided views of the external terrain, deployment level and WhMD type. Video image resolution was 720 584, and frame rate was 30 frames per second (FPS), yielding 15 FPS for each of the two cameras. Signs were posted in each bus notifying passengers that activities are being monitored and recorded for public safety. Ramp slope was measured using an analog inclinometer (VTI, SCA121T-D05, Vantaa, Finland) securely mounted within the ramp structure. The ramp inclinometer was calibrated upon installation to convert the output voltage to a corresponding ramp angle. Inclinometer calibration was verified every two months. The inclinometer provided a ±90 measuring range with 0.0035 resolution. Inclinometer output was recorded at 1 Hz using a data logger (Omega OM-CP-VOLT101A-15V, Stamford, CT). The data logger was positioned to provide easy access for periodic download of recorded data. Video files and data logger recordings were time-stamped, allowing for synchronization. Audible feedback in the form of discrete repeating signals was provided to the bus operator when the switch to kneel the bus floor was activated. Extent of bus kneeling was determined by calibrating the number of discrete audible signals to the percent of full kneeling across the possible range. The number of discrete audible signals was determined for each ramp deployment using the video camera audio recording capability. Twelve discrete audible signals equated to full kneeling. Extent of kneeling was recorded in the database as percentage of full kneeling (e.g. six discrete signals equated to 50% kneel). An interlock control prevents ramp deployment without engaging the switch to kneel the bus; one discrete signal yielded the minimum possible kneeling. Bus floor height was found to decrease from 39.4 cm to 30.5 cm when fully kneeled compared to minimally kneeled. This equated to a 5.2 reduction in ramp slope from minimal kneel to full kneel when deployed to flat level ground. Procedure Ramp slope and video data were collected over a 15-month sequential period. Video recordings and inclinometer data were retrieved every 7–10 days for analysis. A FileMaker Pro database (Ver. 12, Santa Clara, CA) was used to abstract video and ramp slope data for WhMD-passenger boarding and alighting events. Data collection included recording WhMD type and drive wheel position, ramp deployment level (street, sidewalk), percent (extent) of bus kneeling (i.e. 100% equates to full kneeling) and ramp slope.
Public transit bus ramp slopes measured in situ
DOI: 10.3109/17483107.2014.913714
Data analysis Descriptive statistics were used to describe ramp slope means and standard deviations, along with frequency distributions. Statistical analysis was performed using SPSS (Ver. 21, IBM, Armonk, NY) to determine if deployed ramp slopes and extent of bus kneeling differed based on boarding versus alighting activity, WhMD types and deployment level (street versus sidewalk). Normally distributed data were analyzed using ANOVA; data failing to meet assumptions of normality were analyzed using Mann–Whitney Utest. Kruskal–Wallis ANOVA was used to examine differences in ramp deployment conditions across WhMD type. Determination of significance was established at p 0.05. Pearson’s correlation was used to evaluate the relationship between extent of bus kneeling and deployed ramp slope.
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Results
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public transit vehicles and averages between 10 400–13 000 annual WhMD trips. The geographic region sits on a wide, flat flood plane with gently rolling hills. Four hundred seven WhMD-seated passengers were observed boarding and alighting the bus. (One WhMD-seated passenger boarded without ramp deployment, one alighted without ramp deployment and one WhMD-seated passenger alighting process was not captured on video leading to slight differences in sample size reported in the figures.) Observations included 303 power wheelchairs (74.5%), 68 manual wheelchairs (16.7%), 33 scooters (8.1%) and three attendant-propelled adult strollers (0.74%). Among power wheelchairs, 125 were front wheel drive (41.3%), 148 were mid wheel drive (48.8%) and 30 were rear wheel drive (9.9%). In two cases only boarding was captured and in one case only alighting was captured.
Overview
Ramp slope measurements across boarding and alighting activities
The transit bus used in this study is operated by a public metropolitan transit agency serving a population of approximately 1.3 million. The transit agency operates 240 large, accessible,
Frequency distributions of measured ramp slopes during both boarding and alighting were slightly skewed towards steeper ramp slopes (Figures 1 and 2).
Figure 1. Frequency distribution of observed ramp slopes during boarding (n ¼ 406).
Figure 2. Frequency distribution of observed ramp slopes during alighting (n ¼ 405).
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As might be expected based on frequency distributions, there was no significant difference in mean ramp slope between boarding and alighting activities (p ¼ 0.497) (Table 2). Nor were there significant differences in mean ramp slope between boarding (p ¼ 0.865) and alighting (p ¼ 0.153) based on WhMD type (due to small sample size, attendant-propelled strollers were not included this analysis).
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Ramp slope based on deployment level Ramp slope can be expected to differ based on the built environment (e.g. curbs, curb cuts). We compared mean ramp slope during boarding and alighting activities based on ramp deployment level (street versus sidewalk). The ramp was more often deployed to sidewalk level versus street level during boarding and alighting activities (92.0 and 90.8%, respectively). However, mean ramp slope was approximately 7o greater when the ramp was deployed to street versus sidewalk level; this difference was statistically significant (p ¼ 0.000) (Table 3). Additionally, when deployed to street level, more than half of ramp slopes exceeded the proposed ADA guideline for maximum ramp slope (9.5o) during both boarding and alighting (Table 4). Relationship between bus kneeling and ramp slope The bus was kneeled 50% or greater during the majority of ramp deployments; however, during boarding, the mean percentage of bus kneeling was greater (73.1% ± 21.6%) than during alighting (68.4% ± 23.6%), and this difference was statistically significant (p ¼ 0.014). Additionally, although the ramp was more often deployed to sidewalk level during boarding and alighting activities, findings showed a significant difference between mean percentage of bus kneeling when the ramp was deployed to street level versus sidewalk level. When kneeled to street level, the mean percentage of bus kneeling was 83.6% ± 16.2%,
Table 2. Mean ramp slopes for boarding and alightinga.
WhMD type
Boarding – Mean ramp slope (deg ± SD) 4.3 4.3 4.5 4.3
All Manual Power Scooter
Alighting – Mean ramp slope (deg ± SD)
(±2.9 ) (±2.9 ) (±2.8 ) (±2.7 )
4.2 4.0 4.1 5.1
(±3.1 ) (±2.6 ) (±3.0 ) (±3.5 )
a
Ramp slopes for three strollers were 1 , 3.5 and 10.5 in boarding and 15 , 9 and 9.5 in alighting.
Table 3. Ramp slope based upon deployment level. Ramp slope in boarding
Ramp slope in alighting
Street level Sidewalk level Street level Sidewalk level (n ¼ 33) (n ¼ 373) (n ¼ 37) (n ¼ 368) Mean (±SD) 10.6 (±2.5) Maximum 15.5
3.8 (±2.1) 11.5
10.2 (±2.1) 15
3.6 (±2.4) 13.5
Table 4. Percent deployments exceeding proposed maximum allowable ADA allowable ramp slopea based upon deployment level.
Boarding (n ¼ 406) Alighting (n ¼ 405) a
Sidewalk level
Street level
1.9% 1.4%
66.7% 56.8%
Proposed ADA maximum ramp slope ¼ 9.5 (1:6).
compared to 69.5% ± 22.9% during sidewalk level boardings/ alightings (p50.01). Full kneeling occurred during 17.8% of boardings/alightings. Operators fully kneeled the bus almost twice as often during street level boardings/alightings (30.4%) compared to sidewalk level boardings/alightings (16.6%). Interestingly, the percentage of bus kneeling was not correlated to ramp slope (r ¼ 0.054) (Figure 3). Nor was there a significant difference (p ¼ 0.106) in the mean percentage of bus kneeling across WhMD types. We also examined the percentage of bus kneeling for the subset of ramp deployments that exceeded the proposed ADA maximum ramp slope of 9.5 (n ¼ 54). The mean percentage of bus kneeling within this subset was 81.0% (±19.6%).
Discussion Over half of ramp deployments to street level exceeded the proposed ADA maximum allowable ramp slope (9.5 or 1:6). This finding suggests that transit agencies may have difficulty complying with the proposed ramp slope changes to the ADA Accessibility Guidelines for Transportation Vehicles when ramps must be deployed to street level. We measured achievable ramp slopes of the bus used in this study under full kneeling conditions when the ramp was deployed to both street and sidewalk level (level surface, no cross slopes). When fully kneeled and deployed to street level, the achievable ramp slope was 9.5 . When fully kneeled and deployed to a sidewalk with a 15.2 cm (6 in) curb, the achievable ramp slope was 2 . Ramp and bus design, as well as the built environment, can influence the minimum achievable ramp slope. The bus used in this study was equipped with an interlock control that prevented ramp deployment without activation of bus kneeling, but the bus operator controlled the percentage of kneeling. This interlocking control is not required by ADA; it is a vehicle manufacturer option that is specified by individual transit agencies during the vehicle procurement process. In some instances where steep ramp slopes were measured (maximum of 15.5 ), we observed exterior terrain that sloped away from the bus, so that the distal end of the ramp interfaced with the exterior surface at an elevation below street level. Thus, when deploying to street level with terrain sloping away from the bus, the proposed maximum allowable slope could be exceeded despite full kneeling of the bus floor. Conversely, when deployed to a high sidewalk curb with upward sloping terrain, it was possible for the distal end of the ramp to be higher than the proximal interior end, resulting in a negative slope. Additionally, sidewalk deployments were not always to a typical 6" (14.7 cm) curb. Although we were not able to measure curb height, we observed sidewalk curbs at elevations only slightly above the street level. These conditions may contribute to steep ramp slopes during sidewalk deployments despite a high extent of kneeling initiated by the bus operator. Cross-sloping streets and sidewalks, and the distance between the stopped bus and sidewalk can also affect ramp slope. Sidewalks typically slope towards the street to promote drainage. A ramp deployed from a bus located in close proximity to the sidewalk will result in the distal end of the ramp resting on the sidewalk at a higher elevation compared to a ramp deployed from a bus located farther from the sidewalk (Figure 4). Thus, a lesser slope can often be achieved when the bus stops in closer proximity to the curb. ADA Guidelines specify a maximum cross slope of 1.19 (1:48) for sidewalks [11]. However, measurement of streets and sidewalks in the transit area where our study was conducted revealed cross slopes up to 2.3 on streets and 2.2 on sidewalks. When deploying a 1.22 m ramp (the length of the ramp used in this study) under cross-sloping street and sidewalk
Public transit bus ramp slopes measured in situ
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DOI: 10.3109/17483107.2014.913714
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Figure 3. Percentage of full kneel versus ramp slope (n ¼ 799).
Figure 4. Bus stopped on cross-sloping street deploying the ramp to a cross-sloping sidewalk.
conditions, a 1 m change in bus to sidewalk distance can translate to as much as a 3.7 difference in ramp slope. Excessively steep ramp slopes and negative slopes may, in some cases, be improved or resolved by bus operator actions. We observed one operator advising a WhMD user to move from the street to a sidewalk to minimize ramp slope and making it easier and safer to ascend the ramp. However, in other cases, operators were observed deploying the ramp to street level when a curbed sidewalk was available nearby. Partial kneeling contributed to overly steep ramp angles in some cases, while excessive kneeling, when deploying to sidewalks with high curbs contributed to negative ramp slopes. Negative slopes can present challenges during ramp use for mid-wheel drive power WhMDs by causing drive wheels to lose contact with the ramp surface as the front and rear casters ‘‘bridge’’ across the ramp and bus floor. Given the lack of significant difference in deployed ramp slope across WhMD types, it would appear that vehicle operators were not influenced in their deployment behaviors based upon whether a WhMD user was able to traverse the ramp using electric power or through self-propulsion. The lack of correlation between percentage of bus kneeling and ramp slope may be partially explained by operator choice of deployment location, cross-sloping deployment surfacesand variations in sidewalk curb heights. Differences in the percentage of bus kneeling between street and sidewalk level ramp deployments suggests that bus operators tend to kneel the bus more when anticipating a steep ramp slope (i.e. deployment to street level). Similarly, when the bus was kneeled only slightly, high curbs were often observed during ramp deployment. The majority of ramp deployments occurred when the bus was kneeled 50% or greater. However, full kneeling can reduce ramp slope by up to 5.2 , while a change from 50% kneeling to full kneeling can reduce ramp
slope up to 2.6 . Given observed ramp slopes ranging from 4 to 15.5 in this study, it is clear that a combination of factors, including kneeling, can affect ramp slope. In cases where ramp slope exceeded the proposed ADA maximum ramp slope, we observed that some operators stopped short of full kneeling. While the majority of these scenarios occurred when the ramp was deployed to street level, some instances occurred when the ramp was deployed to the sidewalk level (Figure 3). Conversely, during some deployments, the proposed ADA maximum allowable ramp slope was exceeded despite the bus operator fully kneeling the bus (Figure 3); this occurred in deployments to both street and sidewalk levels. This scenario points to conditions of the built environment preventing the operator from achieving a more accessible ramp slope. When considering the proposed the ADA maximum ramp slope 9.5 (1:6) it is of interest to compare slopes of a WhMD user may encounter when navigating the built environment. ADA Accessible Routes Guidelines Section 405.1 [12] states that ramps along accessible routes shall have a running slope not steeper than 1:12 or 4.8 . Consequently, WhMD users capable of navigating the built environment may be presented with an ADA-compliant ramp slope that is twice as steep when boarding or alighting from a transit vehicle. Clearly this inconsistency between existing and proposed ADA Guidelines can introduce challenges or barriers to independent and safe access. The inherent stability of a WhMD when ascending/descending a ramp is also of interest given that instability can contribute to WhMD tipping and associated user injuries [13]. RESNA Wheelchair Standards [14] evaluate dynamic stability of power WhMDs ascending and descending inclined planes having a slope of 0 , 3 , 6 and 10 when occupied with a 100 kg surrogate. During testing, a score of 0 to 4 is assigned to a WhMD based upon the number of wheels remaining in contact with the inclined surface and whether or not tipping occurred (4 ¼ one uphill wheel remains in contact with surface; 0 ¼ WhMD tipped over). When evaluating dynamic stability, Rentschler et al. [15] found that none of the power WhMDs tested maintained all wheels in contact with a 10 inclined surface. These findings suggest that ascending or descending a ramp slope of 10 , only 0.5 steeper than the proposed maximum allowable ADA ramp slope for accessing transit vehicles, could lead to WhMD instability. The Centers for Medicare and Medicaid Services (CMS) require that power WhMDs be tested and proven to be stable on inclined slopes of either 6 , 7.5 or 9 , depending upon WhMD classification (i.e. Group 1 through Group 5) [16]. Thus,
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Medicare or Medicaid-reimbursed power WhMDs are not required to maintain stability on slopes as steep as the ADA proposed maximum allowable ramp slope of 9.5 . In other words, power WhMDs covered by Medicare or Medicaid are not required to be dynamically stable on ADA-compliant slopes that a WhMD user may encounter when accessing a transit vehicle. This incompatibility between proposed ADA Transportation Vehicle Guidelines and existing ADA Guidelines for Accessible Routes and CMS power WhMD stability testing criteria may lead to a loss of independence when accessing transportation vehicles or even place WhMD users at an increased risk for injury when traversing vehicle ramps. Findings from our study suggest that compliance with the proposed ADA maximum ramp slope may not be achievable given existing vehicle and ramp designs, and varying conditions of the built environment. Training focused on providing an improved understanding by bus operators of factors contributing to increased ramp slope would benefit WhMD user access to public transit buses. Transit agency policies, such as not deploying to street level (when possible), should be implemented to reinforce best operator practices. Incorporating inclinometers within ramps, combined with real time feedback and alert systems could be useful to signal vehicle operators and WhMD users when ramp slope exceeds a threshold or is too steep for independent or safe access. Improvements in vehicle and ramp manufacturer design guidelines, as well as bus stop designs, that anticipate their effects on ramp deployment are also needed. For example, requiring control interlocks that prevent ramp deployment without bus kneeling should be compulsory. Similarly, comprehensive assessments of bus stop built environments by transit agencies to assure appropriately elevated surfaces above street level are present to receive deployed ramps are also warranted. Limitations Findings were based on observations of a single vehicle model and manufacturer and a single ramp design. Varying ramp and vehicle designs, as well as varying geographical regions, may result in different ramp slopes encountered by WhMD users. Additionally, bus operator practices may vary across transit agencies. Thus, these findings are not generalizable across transit agencies throughout the US. Additionally, we were unable to assess conditions of the built environment where ramp deployments occurred, and thus were not able to specifically describe built environment-related factors (e.g. sidewalk curb elevation relative to street, sidewalk and street cross-slopes) for each deployment that may have contributed to the inability to achieve the least practicable ramp slope. Similarly, we were unable to determine proximity of the bus to the sidewalk curb for each deployment.
Conclusion This study utilized a ramp-embedded inclinometer in conjunction with videography on a large accessible, low floor transit bus to characterize ramp slope when deployed for WhMD user boarding and alighting. Over half of ramp deployments to street level in boarding and alighting exceeded the proposed ADA maximum allowable ramp slope of 9.5 . Ramp deployments to sidewalk level exceeded 9.5 in less than 2% of deployments. Deployment level (street versus sidewalk) and the built environment, specifically sidewalk and street cross slopes, as well as sidewalk curb height, can have a substantial effect on ramp slope. Bus operator controlled factors such as extent of bus kneeling and ramp
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deployment location can influence ramp slope. Although operators deployed the ramp to sidewalk level in most cases of boarding and alighting, they tended to kneel the bus to a greater extent for WhMD user boarding than alighting. Operator education conveying the influence of their actions on ramp slope during WhMD user boarding and alighting should be emphasized in transit agency training programs. Additionally, urban planners should anticipate the effects of the bus stop built environment and terrain on ramp deployment.
Declaration of interest This study was funded by the National Institute on Disability and Rehabilitation Research (NIDRR), Field Initiated Projects program, Grant #H133G110074. The opinions expressed herein are those of the authors and do not necessarily reflect NIDRR opinions. The authors have no other declarations of interest to report.
References 1. LaPlante M, Kaye HM. Demographics and trends in wheeled mobility equipment use and accessibility in the community. Assist Technol 2010;22:3–17. 2. Americans with Disabilities Act of 1990, Pub. L. No. 101–336. 104 Stat. 328;1990. 3. Kaye HM, Laplante M. Mobility device use in the United States. Washington, DC: Department of Education; 2000. 4. National Council on Disability. The current state of transportation for people with disabilities. Washington, DC: National Council on Disability; 2005. 5. Buning ME, Getchell CA, Bertocci GE, Fitzgerald SG. Riding a bus while seated in a wheelchair: a pilot study of attitudes and behavior regarding safety practices. Assist Technol 2007;19:166–79. 6. Easter Seals Project Action. Status report on the use of wheelchairs and other mobility devices on public and private transportation. Washington, DC: Easter Seals Project Action; 2008. 7. Frost KL, Bertocci G. Retrospective review of adverse incidents involving passengers seated in wheeled mobility devices while traveling in large accessible transit vehicles. Med Eng Phys 2010;32: 230–6. 8. Frost KL, Bertocci G, Sison S. Ingress/egress incidents involving wheelchair users in a fixed-route public transit environment. J Public Transport 2010;13:41–62. 9. Architectural and Transportation Barriers Compliance Board. ADA Accessibility Guidelines (ADAAG) for Transportation Vehicles. 36 CFR Part 1192; 1998. 10. Architectural and Transportation Barriers Compliance Board. Americans with Disabilities Act (ADA) accessibility guidelines for transportation vehicles. NPRM 75 FR 43748; 2010. 11. Department of Justice, 2010 ADA Standards for Accessible Design, Sept. 15, 2010. 12. Architectural and Transportation Barriers Compliance Board. Americans with Disabilities Act (ADA) Accessibility Guidelines for Accessible Routes – Ramps Section 405.1; 2004. 13. Calder C, Kirby R. Fatal wheelchair-related accidents in the United States. Am J Phys Med Rehabil 1990;69:184–90. 14. Rehabilitation Engineering Society of North America (RESNA). RESNA WC-2:2009 American National Standard for Wheelchairs Vol. 2: Additional Requirements for Wheelchairs (including Scooters) with Electrical Systems. Arlington (VA): RESNA; 2009. 15. Rentschler A, Cooper R, Fitzgerald S, et al. Evaluation of selected electric powered wheelchairs using the ANSI/RESNA Standards. Arch Phys Med Rehabil 2004;85:611–19. 16. Centers for Medicare and Medicaid Services, Technical Expert Panel Report – Power Mobility Device Coding Guidelines. August 2006. Available from: https://www.dmepdac.com/resources/articles/ 2006/08_14_06.pdf [last accessed 7 Apr 2014].
