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Trans. Planning Journal
| Title | The Grade Adjustment Factor of Queue Discharge Behavior on Divided Urban Streets |
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| Author | Pin-Yi Tseng, Feng-Bor Lin, Hsin-Yi Yang and Siao-Yu Chang |
| Summary | Many urban streets in Taiwan have underpasses or viaducts to minimize conflicting traffic movements. These underpasses are generally short and include a signalized intersection at the upgrade end. Similarly, the off-ramps of viaducts usually include a signalized intersection at its downgrade end. The queue discharge characteristics at such intersections and the resulting lane capacities may be affected by the grades of the adjacent underpasses or off-ramps of viaducts. The Taiwan Highway Capacity Manual (HCM) applies a grade adjustment factor to the estimated queue discharge rate of a level traffic lane to assess the impact of grades. But the adjustment factors used in this manual are not based on the traffic characteristics in Taiwan. Focusing on intersections located on urban streets that have median barriers without exclusive bus lanes and divided express and local lanes, the researchers of the present study collected and analyzed the queue discharge data of seven lanes. Results showed that the approach grade at an intersection had a significant impact on queue discharge rate and that the impact was greater than that indicated in the HCM published by the U.S. Transportation Research Board. The present study proposed a regression model for this road type to estimate the grade adjustment factor (fg). |
| Vol. | 44 |
| No. | 2 |
| Page | 145 |
| Year | 2015 |
| Month | 6 |
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