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Pace Development Guidelines |
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Pace Development Guidelines |
C. BUS TURNOUTS
Bus turnouts are bus stop areas that are recessed from the thoroughfare. The turnout provides an en route bus with an off-street service point that does not interfere with traffic movement and provides a safe waiting area for transit users. These facilities should be designed so that bus operators have clear rear-vision capabilities necessary for safe re-entry into traffic.
The recommended width for turnout designs is 15 feet for arterials and 20 feet for highways. These dimensions provide bus operators with ample space to properly maneuver and stop their vehicles particularly during the winter season when snow and ice are present.
Figure IV-2 identifies the recommended taper, bus bay and acceleration/deceleration lane dimensions of a bus turnout based on vehicle speed. A bus turnout should be constructed with a concrete landing pad that covers the entire turnout area. Concrete pavement is necessary due to the deterioration of asphalt pavements from petroleum distillate deposits and frequent bus starts and stops.
Acceleration and deceleration lanes should be provided to accommodate speed changes necessary for the bus to enter and exit traffic. These lanes vary in length depending on traffic speeds and volumes and include tapers that guide the vehicles' removal from the roadway. Also, the number of 50-foot bus bays placed in a turnout will vary depending on service volume and transfer needs. However, the actual design of a turnout will depend on local site conditions, the volume of service and passenger transfer needs; space constraints may limit the size of turnouts while service volumes may necessitate their expansion (the addition of more bus bays) to accommodate additional buses. If more than 1 bus bay is required, bus berth designs should be followed.
Bus turnouts are needed in areas where passenger volumes are high and the flow of traffic could be significantly impeded by stopped transit vehicles. However, these turnouts should be located only at mid-block bus stop locations, allowing buses to re-enter traffic more easily during gaps in the traffic flow. This is particularly important since the bus will be merging with traffic. (Construction of bus turnouts at near-side and far-side bus stop areas are generally not recommended).
The construction of bus turnouts on highways requires additional buffering from traffic due to the increased speeds on these roadways. Pace recommends the use of AASHTO bus turnout dimensions for highways(1) as a general guide for their construction. A 20-foot bus bay width allows adequate space to pass a standing bus. A minimum 8-foot buffer and 10-foot shoulder must be constructed to separate the continuous traffic flow from transit vehicles that are decelerating and accelerating. A passenger waiting area also must be provided for the convenience of transit users. While the dimensions of the entire waiting area will vary depending on the site, the passenger loading area and shelter dimensions should be consistent with those described in Section V, Figure V-3.
1. American Association of State Highway and Transportation Officials, A Policy on Geometric Design of Highways and Streets (Washington, D.C.: 1990), pg. 405-407.
Revised: November, 1999.