The Analysis Of A Delay Model For Roundabouts

Modern roundabouts, first installed in England in the early1960s, are becoming popular substitutes for signalized and stop controlled intersections in the United States. These facilities were originally introduced in order to solve the problem of the traditional roundabout. Using the principle that entering traffic yields to circulating traffic, or the "give way" rule, roundabouts was proved to be a much more efficient and safer intersection.The average time a driver has to wait before he can cross the roundabout has been a major performance indicator. By use of models, analysts can compare the operational performance of various intersection configurations prior to implementation.Firstly,the paper introduced the difference between traditional roundabouts and modern roundabouts,then summarized the development, types, the advantages and the disadvantages and suitable places of roundabouts. Secondly, the paper presented the traffic flow theory which is related to the delay of roundabouts, such as queuing theory, gap acceptance theory and the headway model; Thirdly, introduced the concept of delay, analyzed the influence factors of delay, and summarized the existing delay models of roundabouts; At last,a delay estimation model for roundabout approaches has been developed and compared to delay measured in the field at roundabouts in Dalian, queuing theory was used to develop this model which is applicable under steady state conditions and with the assumption ofan M/G/1queuing regime.