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Environmental Design and Civil Engineering for Persons with Disabilities

Yang Shu-Qi and Zhao Tian-Wei, Beijing Municipal Engineering Design Institute, Beijing, China

Introduction

In order to meet the travel needs of persons with disabilities and to lessen the difficulties which they encounter in streets, it is necessary to improve environmental conditions to ensure their convenience and safety. In this paper, we investigate and discuss appropriate measures in street construction under special consideration of Chinese urban traffic conditions. We have thoroughly studied the design principles and technical requirements for bicycle lanes, sidewalks and pedestrian crossings as well as overpasses and tunnels for pedestrians, in order to specify accessibility guidelines.

Barrier-Free Street Design

In China, most urban inhabitants travel by bicycle or bus. There are special lanes for bicycles and some major intersections are designed to separate bicycle from motor traffic.

Chinese citizens with disabilities use hand-driven or motorized tricycles which can ride on bicycle lanes. By taking the tricycle, persons with mobility impairments can meet their various needs, such as go to work, attend school, and take part in various social activities. They can cross streets conveniently, travel by themselves and avoid the difficulties involved in taking the bus.

Since Chinese cities have bikeways, bicycle lane design must take into consideration the performance of hand-driven tricycles. For this reason, the bikeway’s maximum gradient should be 2.5%. This maximum gradient is suitable only for flat and near-flat terrain of cities and towns. In mountainous areas, the maximum gradient is 3.5%, but the length of the maximum gradient should not exceed 80 m. Where the topography is very hilly, the performance of motor tricycles should be the guideline with a maximum gradient of 7%.

Arterial and secondary trunk roads, feeder roads and residential streets should be considered without exception as focal points for persons with disabilities in environmental design. Only streets constructed with the gradients mentioned above can be considered barrier-free. In city planning, the department of public utilities, the governmental department and disability organizations cooperate in order to effectively serve the interests of persons with disabilities.

Designing Sidewalks and Pedestrian Crossings for People with Disabilities

Sidewalks and pedestrian crossings are thoroughfares for daily activity. In China, even though the standard of facilities for persons with disabilities is inferior, the engineering design standard of sidewalks and pedestrian crossings must be satisfactory.

Sidewalks and pedestrian crossings must meet the differing demands of persons with disabilities.

For the convenience of persons with disabilities, the curb height at intersections should be lowered, and an access ramp provided for pedestrian crossings. The gradient of the access ramp is less than 2%.

The sidewalk’s width is designed according to the peak hour volume of pedestrian traffic for a capacity of 1800-2000 p/h.m. The minimum width of the sidewalk is 2.5 m. In commercial districts, docks and railway stations, the width is never less than 4 m.

In designing pedestrian crossings, not only the needs of persons using tricycles or wheelchairs have to be considered but also the convenience and safety of people with sight impairments. Sight-impaired people depend upon their tactile sense to recognize the street and its position . For their convenience, the sidewalk’s inside curb must be 10 cm higher than street level.

The width of the pedestrian crossing depends upon peak hour volume which is approximately 2000 - 2400 p/h.m.

Curbs at the pedestrian crosswalks must be lowered. A slope of 1 in 20 should not be exceeded.

If a street has two separators, the separator at the pedestrian crossing must be cut off, so that persons with disabilities can cross freely.

At pedestrian crossings, no barriers such as trees, electrical poles, rain water drains, etc. are permissible.

For the safety of sight-impaired pedestrians audio signals should be installed. When a button is pushed, the signal changes to green and a sound is emitted. The warning time must be sufficient for the pedestrian to safely reach the other side of the street. Without pushing the button, no sound is emitted in order to reduce urban noise.

Audio signals should be set up at zebra crossings. A protecting handrail should be placed next to the signal in order to hinder accidental access into the street. The duration of the green signal is based on the normal walking speed of a blind person, 0.9 - 1.2 m/sec.

At intersections and pedestrian crossings, curb height must be lowered to 2 cm or less. This is a help for persons using tricycles and wheelchairs. It also reduces the accumulation of rain water. The lowered section of the curb must connect with the abutting curb by a smooth slope.

In order to assist persons with impaired vision to distinguish which way the walking direction lies at the pedestrian crossing, the crosswalk should be paved with tactile square bricks in a yellow color. Such a crosswalk should be paved by two kinds of bricks for tactile feeling - one for the walking direction and the other for ’stop’.

Designing Pedestrian Overpasses and Tunnels

Since traffic volume and speed increase daily, pedestrian overpasses and tunnels are necessary in order to improve street environment. In Chinese cities the construction of pedestrian overpasses and tunnels is developing rapidly. If barrier-free design is not made mandatory, many new difficulties will arise for persons with disabilities. For their convenience and safety, careful research on related facilities must be carried out by engineers.

While many special bikeways have been constructed for disabled people for crossing streets with hand-tricycles, pedestrian overpasses and tunnels are mainly for disabled persons who walk using canes and crutches.

The minimum width of the steps is 30 cm, maximum step rise is 15 cm. After the maximum of 12 steps there must be a landing for resting with a width of 1.5 m.

The width of overpass bridge and sidewalk tunnel must satisfy the capacity of 1800 -2000 p/h.m. In crowded areas, 1400 p/h.m. is used.

In order to the meet the needs of persons with disabilities, handrails must be installed on overpasses and on tunnel walls. This aids persons with disabilities in climbing and resting protecting them from falling.

Handrails are installed at 90 cm above walking level and must be 30 cm longer than the stairs.