INFLUENCE OF ROAD GEOMETRY AND PERCENTAGE OF HEAVY VEHICLES ON CAPACITY AT MULTI-LANE HIGHWAYS IN EGYPT

Multi-lane highways symbolize the plurality of the overall length of highway network in Egypt. The most serious factors affecting the capacity for any roadway are counted the road geometry and the percentage of heavy vehicles (HV). Subsequently, this research aims to discuss the relationship between the road geometric characteristics and HV, and capacity by statistical modeling. The modeling is divided into two models. First is the modeling for capacity on one direction of flow (COD) and second is the modeling for capacity on right lane (CRL). In this study, the road geometric and traffic data are collected from straight section at 28 various sites that are located in desert highways. These sites are separated into 14 sections in divided four-lane roads, 7 sections in divided six-lane roads, and 7 sections in divided eight-lane roads. The results showed that the statistical modeling gives models with high R 2 (coefficient of determination) and low ǁδǁ (percent error) values for estimating COD and CRL. In addition, the most influential variables on COD in all sites are lane number (NL), median width (MW), and HV respectively, while the most influential variables on CRL in all sites are MW and HV, respectively. These results are so important for road authorities in Egypt as they can determine capacity for different straight sections and improve the traffic performance of them in the future.