Bus Bulb
Bus Bulb
A bus bulb, also referred to as a bus boarder, bus border, bumpout, bus cape, or kerb outstand, is a street design feature that extends the sidewalk or pavement into the roadway to provide a more efficient and accessible space for public bus transportation. This design is utilized to facilitate the boarding and alighting of passengers from buses, reducing the time a bus spends merging in and out of traffic. The concept aims to improve public transit systems by optimizing bus stop locations in urban areas.
Design and Functionality
Bus bulbs are strategically installed at bus stops to align the boarding area with the bus lane. This eliminates the need for buses to move out of the traffic lane when picking up or dropping off passengers. The extension into the roadway ensures that the bus can maintain its travel lane during stops, enhancing efficiency and minimizing overall travel time for the route.
Benefits
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Time Efficiency: By keeping the bus in the travel lane, bus bulbs reduce delays caused by re-entering the flow of traffic. This is particularly beneficial in high-density urban areas where traffic congestion is prevalent.
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Accessibility: The extended sidewalk area helps in providing better access for pedestrians and individuals with disabilities, including those using wheelchairs as per the regulations in accessible transportation.
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Safety: Bus bulbs enhance the safety for boarding and alighting passengers by providing a larger, more visible area. This also minimizes the need for pedestrians to navigate around parked vehicles.
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Traffic Calming: As a specialized form of curb extension, bus bulbs contribute to traffic calming, encouraging slower driving speeds and creating a safer environment for all road users.
Integration with Bicycle Infrastructure
The National Association of City Transportation Officials (NACTO) recommends modified bus bulb designs to accommodate bicycle lanes. Two types have been identified:
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Boarding Islands: These structures route the bicycle lane behind the bus bulb, allowing for uninterrupted bicycle traffic even when buses are stopped.
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Shared Boarding Areas: This design incorporates a ramp to route the bicycle lane through the bus bulb, enabling shared use by both cyclists and pedestrians.
Comparison with Bus Bays
Unlike bus bays or turnouts, which provide a designated pull-off area for buses, bus bulbs keep buses in the flow of traffic. While bus bays allow for the smooth flow of traffic around stopped buses, they require buses to merge back into traffic, potentially causing delays. Bus bulbs, conversely, prioritize bus transit efficiency over the uninterrupted flow of vehicular traffic.
Urban Implementation
In cities like New York City and San Francisco, bus bulbs are part of broader transit improvement programs. They are incorporated into the design of bus rapid transit (BRT) systems and are often accompanied by other measures such as bus lanes and transit signal priority to enhance the overall effectiveness of public transportation.
Challenges
Implementing bus bulbs requires careful consideration of local traffic patterns and street design. In some cases, opposition may arise due to the perceived loss of parking spaces or changes in traffic flow. However, the long-term benefits in terms of transit efficiency and pedestrian safety often outweigh these challenges.