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Trans. Planning Journal
| Title | Representative Vehicles for Design of Grade Segments on Taiwan’s Freeways |
|---|---|
| Author | Pin-Yi Tseng, Feng-Bor Lin, Cheng-Wei Su and Chiung-Wen Chang |
| Summary | To assist in the design and level-of-service analysis of highway grade segments, the Institute of Transportation (IOT), Ministry of Transportation and Communications initiated a project to develop a microscopic simulation model. This model, referred to as Traffic-on-Grade Simulation (TGS) Model, employs Speed-on-Grade (SOG) sub-model to estimate the instantaneous accelerations and speeds of a vehicle on a grade segment. Variation of the free-flow speeds of vehicles is an important consideration in the design of grade segment because it affects not only traffic safety but also level of service. Many countries have specified representative vehicles with various weight-to-horsepower ratios for highway design. For the design of Taiwan’s highways, it is not clear what representative vehicles should be used. This study uses the SOG model to identify representative vehicles that exhibit the average free-flow speed characteristics observed on Taiwan’s National Highway 1. Simulation results reveal representative trailer-truck, single-unit large truck, large bus, and small vehicle (excluding motorcycle) have weight-to-horsepower ratio (in kg/kW) of 125, 64, 75, and 50, respectively. Characteristic relationships between free-flow speed and travel distance of these vehicles on uniform upgrades are presented for design applications. |
| Vol. | 45 |
| No. | 1 |
| Page | 1 |
| Year | 2016 |
| Month | 3 |
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