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Signal Phasing Strategies for Intersections with an Exclusive Bicycle Path
AuthorJayankura, Andrew V.
Civil and Environmental Engineering
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Over the past few years in the United States, there has been a gradual increase among many public agencies installing experimental exclusive bicycle traffic signals in conjunction with vehicular traffic signals. These signals, mostly found at intersections with protected two-way bicycle paths, may cause operational inefficiencies if unsatisfactory phasing strategies are used. The source of the issue stems from difficulty in developing a phasing strategy where simultaneous vehicular movement is to not come into conflict with any concurrent bicycle movement, particularly the vehicular right-turn movement adjacent to a bicycle path. Additionally, as a new signal type, there has been a lack of general guidelines on how to develop an efficient strategy that not only accommodate bicycle traffic signals, but also pedestrian signals. The goal of this research was to develop different strategies to accommodate bicycle traffic signals. The strategies are based on a case study intersection where a bicycle signal has been installed and is causing operational inefficiencies. Three strategies was developed for each split and lead-lag phasing using a combination of overlaps, dummy phases, and phase modifiers. Using the simulation software VISSIM, a model was developed based on the case study's intersection roadway geometry and signal timing. Each strategy is then implemented and evaluated for the capacity and delay of the right-turn lane by varying bicycle and pedestrian volumes. Analytical models based on Poisson distribution were developed for the capacity and delay of the right-turn lane and checked with simulation results for validation. The current intersection operation was also evaluated using current traffic volumes, and implementing all three split design strategies.The results from simulation showed low delays and high capacity for the vehicular right-turn lane at low bicycle and pedestrian volumes. Vice versa, higher delay and lower capacity for the vehicular right-turn lane at higher bicycle and pedestrian volumes resulted, which is expected. A reduction of the current operation's right-turn lane average delay was observed with the implementation of all three solutions. And finally, the results from simulation indicate that each strategy will be advantageous at different bicycle and pedestrian demands.