You are here
TCRP Report 90 Bus Rapid Transit Volume 2: Implementation Guidelines
Levinson, H. , S. Zimmerman, J. Clinger, J. Gast, S. Rutherford, and E. Braun, TCRP Report 90 Bus Rapid Transit Volume 2: Implementation Guidelines. Transportation Research Board, Washington, D.C. (2003)
This report provides state of the art implementaiton guidelines for bus rapid transit systems, which are increasingly being planned for major roadway corridros in the U.S. Of specific relevance to the AMM2 are Section 3-1 (Running Ways) and 4-1 (Traffic Engineering for BRT).Below are guidelines extracted from TCRP 90 with implications for access management, as well as curb parking. Additional details are provided in the report.
Guidelines for planning and implementing on-street running ways include:
- Curb parking generally should be prohibited before (curb) bus lanes are established, at least during peak hours. The prohibition (1) provides a bus lane without reducing street capacity for other traffic, (2) reduces delays and marginal frictions resulting from parking maneuvers, and (3) gives buses easier access to stops.
- Access to major parking garages should be maintained. This may require limited local automobile circulation in blocks adjacent to garages.
- Access to bus stops and stations should be convenient and safe. Curbside stops should allow sufficient space for amenities within the stop or in the adjacent sidewalk. Crosswalks to reach median bus lanes and busways should be placed at signalized locations wherever possible and should be designed to discourage errant crossings.
- Running way design should reflect available street widths and traffic requirements. Ideally, bus lanes should be provided without reducing the lanes available to through traffic in the heavy direction of flow. This may entail eliminating parking or reducing lane widths to provide additional travel lanes, eliminating left-turn lanes, and/or providing reversible lane operation.
- When buses preempt moving traffic lanes, the number of lanes taken should be kept to a minimum. The exception is when parallel streets can accommodate the displaced traffic.
- Generally, far-side bus stops should be provided. They are essential when there are traffic signal priorities for buses and along median arterial busways where left turn lanes are located near-side. Far-side bus stops are desirable where curb lanes are used by moving traffic and at locations with heavy right-turn traffic.
- Bus lanes in the center of streets should be physically separated from other traffic. These median arterial busways will require curb-to-curb roadway widths of at least 75 to 80 feet.
Guidelines for off street running ways involving special bus-only roads and in freeway corridors include:
- BRT access to freeways will benefit from bus-only ramps and/or metered ramps with bus bypass lanes. These ramps have the dual benefits of reducing bus delays and/or improving main-line flow.
- Ideally, busways should penetrate high-density residential and commercial areas, traverse the city center, and provide convenient distribution to major downtown activities. Busways should minimize branching to simplify route structure and station berthing.
- It is generally preferable that downtown off-street busway distribution provide at least three stops at 1?4- to 1?3-mile intervals. This is essential to avoid concentrating all boardings and alightings at one location with attendant increases in bus dwell times.
- Busway stations should be accessible by foot, automobile, and/or bus. These should be placed at major traffic generators and at intersecting bus lines. Park-and-ride facilities should be provided in outlying areas where most access is by automobile.
- Busways can be provided as part of new town developments (e.g., Runcorn) or serve as an access framework for still-to-be-developed areas. This makes land acquisition easier and encourages transit-oriented development.
- Standardization of freeway entrance and exit ramps to the right of the through traffic lanes permits use of median lanes by buses either in concurrent (normal) or contra (reverse) flows. Special bus entry and exit ramps to and from the median lanes should be provided as needed so buses do not have to weave across the main travel lanes.
- Both median and right-side bus lanes are in operation. Median lanes are removed from ramp conflicts at interchanges and can allow special median access to crossroads. However, they require careful design of access points to avoid weaves across the general traffic lanes. Right-shoulder lanes allow easy bus entry and exit. However, they result in frequent weaving conflicts, especially when crossroad entry and exit ramps are closely spaced.
- When a BRT commuter express service (such as in Houston) operates on an HOV facility, it is essential that the BRT service have its own access/egress ramps to off-line transit stations and/or to its park-and-ride facility. Residential off-line collection should be done without requiring vehicles to weave across general traffic lanes to enter and leave the facility.
Some general guidelines from page 4-1 are as follows, with additional details in Chapter 4:
- Stop signs or traffic signals should be placed on streets that intersect BRT routes. Curb parking (all day or during rush hours) should generally be restricted along BRT running ways.
- Left and right turns should be restricted when they cannot be accommodated without delaying BRT.
- Special signage should define BRT running ways and inform motorists of at-grade busway crossings.
- Special BRT traffic signal indicators should be provided to minimize motorist confusion, especially along median arterial busways and at queue jumps.
- Red times (and hence delays) for buses should be kept to a minimum. This can be achieved by (1) maximizing the available green time, (2) using as short a traffic signal cycle length as possible, and/or (3) appropriately advancing and extending green time as BRT vehicles approach intersections.