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Trans. Planning Journal
| Title | A Density Stability Method of Ramp Metering |
|---|---|
| Author | Tien-Pen Hsu & Cheng-Chuan Chien |
| Summary | Conventional ramp metering methods always have some weaknesses in the estimation of capacity, such as demand-capacity method and occupancy metering method. They usually assume that the traffic flow is homogenous and determine the metering rate with preset capacity. ALINEA method improves the capacity estimation by feedback concept of occupancy, but it is also under the assumption of homogenous capacity. In a short control period, it assumes the arrival ratio is the same with the average and depends on it to predict the volume of next control period. In fact, practical traffic does not follow in that way. In view of the stochastic feature and unstable phenomenon especially when traffic becomes heavy, a new concept of ramp metering is developed in this paper based on the predicted instability of density detected on the downstream from the ramp. According to the simulation results using the new density stability concept method maintaining density 2 standard variations less than the critical density can prevent congestion and produce more throughputs on the ramp. The method developed in this paper is then called density stability ramp metering method. |
| Vol. | 30 |
| No. | 2 |
| Page | 275 |
| Year | 2001 |
| Month | 6 |
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