Sub-problem 1c: Analysis of the Signal with Pedestrians and Bicycles

Now that we have been able to optimize the operation of the intersection through the introduction of a traffic signal and reconfiguration to a three-legged form, let's revisit the comparison with a do-nothing approach, which would retain the current stop control on the minor approaches. A comparative summary of these analysis results, based on HCM prescribed procedures, is presented in Exhibit 5-21.

In this case, the difference from do-nothing that is achieved through both operational and geometric modifications is fairly dramatic: in terms of average delay experienced by approaching traffic, the revised intersection results in nearly a 90% reduction in total delay when compared to the current geometric configuration and reliance upon stop control.

Note that both the signalized and TWSC procedures assume adequate left-turn and through movement storage when computing delay. This means that these procedures do not account for the effects of left-turn queues, that might exceed the provided storage and interfere with the through movements, on delay computations. The procedure is also treating the intersection as isolated and will not account for delay effects resulting from through movement queues that could spill back into adjacent intersections. To investigate this issue further, we would need to go beyond the current HCM procedures to employ macroscopic and/or microscopic simulation.