Abstract
Buses operating in mixed traffic are subject to congestion and thus experience long delays and unreliable service. The impact of congestion on buses is more pronounced in downtown areas than elsewhere because of heavy vehicular traffic, high transit–pedestrian activity, and friction caused by curbside users. This research explored potential benefits, effects, and costs associated with bus-only lane alternatives, including effects for traffic, transit, and curbside users (e.g., parking and loading). H and I Streets, Northwest, in downtown Washington, D.C., where bus frequency reaches one every minute during peak hours, were modeled through microsimulation. Concurrent-flow lanes and contraflow bus-only lanes were analyzed. A benefit–cost analysis (BCA) was conducted for each scenario of bus-only lanes. Concurrent-flow bus-only lanes (Alternative 1) offered a low-cost solution with good benefits (reduction as high as 5 min/mi in bus travel time). However, sensitivity analysis showed that enforcement of restrictions on right turns and operations would be needed to ensure these benefits. A contraflow bus-only lane on H Street (Alternative 2) provided substantial improvements in auto and transit travel times without right-turn restrictions and with medium costs. As a result, Alternative 2 provided the most monetary benefits, according to the BCA, with a benefit–cost ratio of 28. Benefits associated with contraflow bus lanes were not contingent on enforcement, because they are self-enforcing. Couplet contraflow bus-only lanes on H and I Streets (Alternative 3) represented the highest-cost solution yet resulted in marginal benefits compared with the other scenarios because of its high impact on auto users.
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