Effect of Rainfall on Traffic Stream Characteristics during Peak and Non-Peak Periods

Abstract

This paper examined the effect of rainfall on traffic stream behaviour during peak and non-peak periods on a basic highway section. Data on this section which is located on the J5 was collected for four months during which 99 rainfall events occurred. The traffic consisted of 75.80% cars, 10.23% motorcycles, 3.51% trucks and 10.46% of other vehicles. Traffic was observed for both rain and no-rain conditions and the data was analysed to see the effect of the rain. The results showed decreases in the speed as the rain intensity increased. Similarly, the traffic flow rates decreased as the rain intensity increased. This trend was observed for both peak and non-peak periods and for both directions. It is concluded that the effect of rain during peak period could have more serious consequences on the traffic flow than during non-peak periods because of the higher flow rates and the constrained nature of the flow. Consequently, capacity degradations up to 30% during peak periods would require resources to be employed to manage the traffic.