Time Headway as Indices of Traffic Congestion

Abstract

Urban mobility problem in Nigeria is on the increase, due to rapid growth in traffic that is not matched with the existing transport infrastructure, resulting in traffic congestion. Headway, a measure of level of service of a roadway, could be instructive in addressing this problem, hence this study. Headway, traffic flow and travel speed were collected for morning and evening peak periods for three consecutive weeks for two selected sections of a road in Ile-Ife, Osun state, using normal procedure. The obtained headway data were subjected to statistical analysis. Headway models were developed using regression analysis and the developed models were evaluated using Adjusted Coefficient of determination ($$R^2$$). The results showed that the traffic along the road was heterogeneous. The maximum safe speed (85th percentile speed) was 31.20 km/hr, while the minimum allowable speed (15th percentile speed) was 28.50 km/hr. The ratio of flow to capacity ($$v/c$$) of the road was 0.65 and thus characterised to operate at level of service C. The headway models were $$h = 0.001n^2 - 0.418n + 35.401$$, $$h = 0.002n^2 - 0.569n + 42.122$$, R-square values of 0.942 and 0.928 and minimum headway values of 5.35 sec. and 5.52 sec. for sections one and two respectively. The road is therefore prone to congestion.