In the example of two-lane highway with one lane closure, the LBSM system employs two phases to regulate the movement of vehicles in the two upstream lanes. Figure 9-7 displays the performance results of the LBSM under different cycle lengths with the upstream demand of 1,000 vphpl and the heavy vehicles of 10 percent. Figure 9: Performance of the LBSM with Various Cycle Lengths The numerical results reflect that the length of 120 seconds (2 min) yields the highest throughput, the lowest average vehicle delay, the least number of stops, and a low average stop delay. In general, a short cycle length may result in less efficient use of the green times, but excessively long cycle length may incur long queues. Usually, an optimal cycle length can be found in the same way under different traffic conditions. Sensitivity Analysis with respect to Impacts of Heavy Vehicles The performance results of the LBSM control system under various heavy vehicle percentages at the volume level of 1,000 vphpl are shown in Figure 9-8. Figure 9: Performance of the LBSM with Various Heavy Vehicle Percentages The graphical results clearly indicate that the presence of heavy vehicles will significantly degrade the operational efficiency of the work zone on all aspects under the LBSM. The optimal cycle length for such a control system seems to increase with the percentage of heavy vehicles. For example, the best cycle length increases from 90 to 150 seconds when the truck percentage increases from 5 to 20%. This is likely due to the fact that the average headway
In the example of two-lane highway with one lane closure, the LBSM system employs two phases to regulate the movement of vehicles in the two upstream lanes. Figure 9-7 displays the performance results of the LBSM under different cycle lengths with the upstream demand of 1,000 vphpl and the heavy vehicles of 10 percent. Figure 9: Performance of the LBSM with Various Cycle Lengths The numerical results reflect that the length of 120 seconds (2 min) yields the highest throughput, the lowest average vehicle delay, the least number of stops, and a low average stop delay. In general, a short cycle length may result in less efficient use of the green times, but excessively long cycle length may incur long queues. Usually, an optimal cycle length can be found in the same way under different traffic conditions. Sensitivity Analysis with respect to Impacts of Heavy Vehicles The performance results of the LBSM control system under various heavy vehicle percentages at the volume level of 1,000 vphpl are shown in Figure 9-8. Figure 9: Performance of the LBSM with Various Heavy Vehicle Percentages The graphical results clearly indicate that the presence of heavy vehicles will significantly degrade the operational efficiency of the work zone on all aspects under the LBSM. The optimal cycle length for such a control system seems to increase with the percentage of heavy vehicles. For example, the best cycle length increases from 90 to 150 seconds when the truck percentage increases from 5 to 20%. This is likely due to the fact that the average headway