Traffic signal control at roundabouts is proved to be effective in addressing heavy traffic. However, the applicability of a signalised roundabout, especially compared with a signalised intersection, in terms of capacity has not been investigated. For signalised roundabouts, unsignalised roundabout capacity models including gap‐acceptance theories and regression models are not applicable. This study first introduces a shockwave‐based model to capture the impacts of signals at circulatory lanes on queuing and clearance time of left‐turning vehicles. On this basis, a general signal timing model and a capacity model are developed. A sensitivity analysis is then elaborated to test how temporal and spatial parameters affect the capacity of a signalised roundabout. Capacity comparisons are made among signalised roundabouts, unsignalised roundabouts and signalised intersections. The results show that (i) under high traffic demand, a signalised roundabout outperforms an unsignalised roundabout; (ii) a signalised roundabout achieve higher capacity than a signalised intersection does under certain condition, (iii) but a signalised intersection outperforms a signalised roundabout when optimal cycle length is relatively short (65 seconds in this study), (iv) capacity of a signalised roundabout is very sensitive to the variation of signal parameters, hence care should be taken to design the parameters to ensure high capacity.
Comparative study on the capacity of a signalised roundabout
IET Intelligent Transport Systems ; 10 , 3 ; 175-185
2016-04-01
11 pages
Article (Journal)
Electronic Resource
English
left‐turning vehicles , signalised intersection , clearance time , temporal parameters , queueing theory , traffic signal control , heavy traffic , spatial parameters , sensitivity analysis , unsignalised roundabout capacity analysis , road traffic control , shockwave‐based model , signalised roundabout , queuing process , traffic demand , capacity model , optimal cycle length , general signal timing model
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