MUTCD: Comments due May 14, 2021
On some narrow transit streets, mixed traffic is expected to use the transit lane both for right turns and to occasionally divert around vehicles waiting to turn left. If enforcement is robust and/or automated, dropping the transit lane approaching an intersection can clarify which movements are permitted.
The dropped transit lane will have a relatively low impact on transit operations, especially where the elimination of double-parking and curbside loading is more important for transit operations than eliminating intersection delay.
Other vehicles may enter the transit lane to circulate around left-turning vehicles, but must rejoin mixed-travel lanes after the intersection when dedicated transit lanes resume.
On transit lanes where automated enforcement is tied to the lane design, it may be important to formally permit through-movements in the transit lane at some intersections.
On two-way streets with one transit and one mixed-traffic lane per direction, where left turns are permitted but no left-turn pocket or lane is present. This condition is most relevant when left-turn volume is low, with one to two vehicles turning per signal cycle.
Dropped transit lanes alleviate mixed-traffic delay and congestion at pinch points by permitting through-moving vehicles to merge right and bypass left-turning vehicles.
Buses and streetcars are generally able to maintain priority, as vehicles utilizing the dropped lane must merge and yield to through-traffic.
Automated enforcement is important to successful implementation.
Mark a skip line between the through mixed-traffic lane and the dropped transit lane to indicate to motorists that they may enter the transit lane, and install through/right arrows at the intersection approach.
Install RIGHT LANE BUS ONLY or other applicable sign where the transit lane resumes.
If private vehicles are permitted to continue across the intersection and merge left after the intersection, use lane reduction arrows (MUTCD Figure 3B-24 F) to direct vehicles back into mixed-travel lanes.
End the transit-only lane 60–100 feet before the intersection, depending on left-turn volume.
If a stop is located at the intersection, provide a far-side in-lane or curbside stop.
For offset lanes, a parking lane line or parking T’s should be provided wherever possible.
Install BUS ONLY word message markings at the end of the bus lane and where it resumes on the other side of the intersection.