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Sub-problem 1a - Page 2 of 9

ID# C201A02

Sub-problem 1a: Maxwell Drive PM Peak Hour - Existing Conditions

Base Case Analysis
The base case run for the existing conditions uses the peak hour volumes shown in Exhibit 2-7, the overall PHF of 0.94, 7% trucks, an arrival type of 2 for the eastbound approach, and an arrival type of 3 for the westbound and southbound approaches. In addition, since the eastbound left-turn phase is skipped half the time, the signal timings for phase 2 are halved to reflect the fact that that phase arises only 50% of the time. The input data for the base case is available in Dataset 1.

We use arrival type 2 for the eastbound approach because the signal at Moe Road tends to synchronize de facto with the one at Maxwell Drive, even though they are both fully actuated. The average cycle lengths at the two intersections tend to be about the same, and they start discharging traffic at about the same time. The distance between the signals is such that the first vehicle in the respective platoons (Moe-to-Maxwell and Maxwell-to-Moe) tends to arrive just as the signals are reaching maximum green. The signals then turn red, a queue forms, and the pattern repeats. This is more typical for the eastbound approach than for the westbound, because the cycle length at Clifton Country Road is much longer. The two signals are never synchronized in such an antagonistic way.

Exhibit 2-8 presents the base case results for signal timings that about equalize the delays for the critical movements in each phase. The movement-specific delays range from 5.3 to 20.8 seconds per vehicle and the average queue lengths range from 1.8 to 9.9 vehicles.

Exhibit 2-8. Maxwell Drive PM peak - Existing Conditions, Base Case Results
EB Arrival Type Heavy Vehicles Phase Skip Signal Timing Performance Measure EB WB SB OA
L T R Total L T R Total L T R Total
2 Yes Yes Base Delay 18.2 5.3 - 7.7 - 16.7 16.7 17.3 - 20.8 18.5 13.7
Queue 1.8 4.2 - - - 9.9 - 2.4 - 2.7 - -

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