Abstract
When pedestrian, bike crossings, or both are concurrent with a vehicular phase, leading through intervals (LTI) and leading pedestrian intervals (LPI) are signalization techniques that provide a partially protected crossing. With LPI, for a short interval at the start of the crossing phase all traffic is held, enabling some pedestrians to arrive at the conflict zone and thus reinforce their priority before turning vehicles are released. LTI functions similarly except that during the leading interval only turning traffic is held; through traffic is allowed to run. This lessens the negative effect on capacity of LPI, and consequently allows LTI to have a longer leading interval, thus affording pedestrians and cyclists greater protection. Experience of LTI in the cities of Montreal, New York, and Charlotte is reviewed. A model is developed to estimate capacity loss from using LPI and LTI for a range of scenarios in which right turns share a lane with through traffic, in which case LTI can indirectly block through vehicles positioned behind a turning vehicle. While LTI’s capacity loss increases with the proportion of right turns, for the wide range of right turn proportions tested, it is still far lower than the capacity loss for an LPI of the same length, especially on multilane approaches.
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