The lane adjacent to the curb can be dedicated to transit vehicles, especially on through corridors where parking is either not provided or not well utilized.
Curbside transit lanes can be implemented with varying levels of separation, increasing service capacity and allowing riders to board directly from the curb.
Application
Where no space for center transitway boarding islands or offset transit lane boarding bulbs exists.
On streets with no curbside parking, or where curbside parking removal is acceptable.
On streets with in-lane sidewalk stops(see Transit Lane Pavement Markings and Color).
On streets with wide sidewalks and furnishing zones that provide space for shelters and strong lateral separation between passing buses and pedestrians in the sidewalk through-zone.
Benefits
Transit vehicles are not delayed by interactions with parking or loading vehicles if well enforced.
A curbside transit lane can have differing, flexible uses throughout the day, such as parking or a shared bus-bike use (see Peak-Only Bus Lane). However, full-time lane dedication improves integrity in some conditions.
Considerations
Special design attention must be given to right turns from streets with curbside transit lanes (see Intersection Design for Transit).
Lanes are prone to encroachment by loading, deliveries, and taxicabs. Enforcement is needed.
Where rain pooling is an issue, gutters and drainage in bus lanes next to the curb must be kept clear to avoid splashing onto the sidewalk. Concrete gutters or lanes may be preferable for curbside bus lanes.
Where snow is a consideration, lanes must be cleared in such a way that plowed snow does not block the lane for transit vehicles. Stop locations must also be kept completely clear of snow at boarding areas.
Because bus stops are typically located directly on the adjacent sidewalk, stops must leave enough room for waiting passengers and passing pedestrian traffic.
Critical
1Designate lanes using a single or double solid white line, as well as a stenciled “BUS ONLY” marking (refer to MUTCD 3D.01). In some jurisdictions, markings may be required for each permitted user (e.g. “TAXI, LRT, BUS ONLY”).
2Signage must designate the transit lane as restricted. Place signs either on the curbside or overhead (MUTCD 2B.20).
Recommended
3Mark the transit lane with red color. Red color treatments are effective in reinforcing lane designation (see Pavement Markings & Color).
Enforcement is critical to the lane’s integrity. Vehicle-mounted video enforcement has demonstrated efficacy in improving transit lane compliance.
The desired width of a curbside bus lane next to a mixed-traffic lane is 10–12 feet, including a gutterpan if present. Bus-only lanes should not typically exceed 12 feet in width. If target operating speeds between stops are low, typically below 25 mph, 11-foot lanes are preferable to 12-foot lanes. If buses operate in an adjacent lane, a 12-foot curbside lane is desired.
Provision for curbside loading can improve compliance, such as timed freight parking on the other side of the street or around the corner from loading destinations.
At intersections with a high volume of turning movements, the curbside lane may need to drop to maintain traffic flow; refer to Intersection Design for Transit for intersection treatment guidance.
Optional
If 13 feet of width is available, full-time curbside bus lanes may be separated with left-side, traversable barriers, such as rumble strips. Separation is not appropriate in all contexts, and must be developed with special care for its impact on walking and bicycling access. If curbing or other hard separation is used, including mountable curbs, bus lanes should be designed to allow passing at selected points. The impact on snowplowing operations should be evaluated when considering the use of curbs to separate the bus lane from other traffic, in climates where snow is a possibility.
4Wider sidewalks, especially those buffered with plantings or furnishings, increase pedestrian safety and comfort adjacent to curbside transit lanes.
Curbside lanes may be separated with hard barriers (e.g. concrete curbs), which may be intermittent or continuous (see Transitways). Where nearly continuous, curbs should at least be omitted for short segments to allow buses to pass, or to allow buses to pass break-downs or incursions.
On very high frequency corridors where bus traffic is significant enough to create congestion, double transit lanes can be implemented curbside. The second bus lane should be designed as an offset transit lane.
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New York City Department of Transportation