EFFECT OF NON-MOTORIZED TRAFFIC ON SATURATION FLOW

Abstract

Intersection describes all roadway situations where two or more roads join or cross one another at the same or different elevation. In developing countries like India crossing of two roads at same level is a common feature because later is very expensive. Design of an at-grade intersection under mixed traffic flow conditions to handle the crossing traffic at satisfactory level of services is the biggest problem encountered by traffic engineers. It is generally observed that congestion at intersection occurs at volume level well below the capacity. Saturation flow and green time ratio are the two factors on which the capacity of the signal controlled intersection depends. Saturation flow will be affected by the several geometric, operating, traffic, environmental and other kind of parameters. For the design of efficient and safe intersection to serve the needs of the existing and future coming traffic it is necessary to have an idea on all kind of affecting parameters of saturation flow. In this Dissertation topic attempt has been made to study the concept of saturation flow at signal control intersections and the influence of non-motorised traffic on saturation flow. Data collected at a signal controlled intersection are analysed to estimate the saturation flows for different approaches and to investigate the effect of non-motorised traffic proportion, effective green time on the saturation flow. Two through and four right turn approaches are considered for the analysis. The vehicles are categorized in to seven categories and PCU values for different vehicle categories are estimated by taking small car as a standard vehicle. The variation in saturation flow with increasing the proportion of non-motorised traffic is examined and explained graphically. Saturation flow for through movement's increases slightly with the increase in proportion of non-motorised traffic. And for right turn movement its effect depend on effective green time also as if effective green time is less then individual vehicles have less time to turning right so they fastly move & ignore the interruption of non-motorised vehicles but if effective green time is more then proportion of non-motorised traffic affect the saturation flow & reduce it. It is observed that Saturation flow decreases with the increase in effective green time. Relationships have been established between effective green time and saturation flow.