Modeling the Safety Effect of Access and Signal Density on Suburban Arterials: Using Macro Level Analysis Method

With rapidly increasing of the land development density along suburban arterials, much more irregular signal spacing appeared on suburban arterials, and high access density is commonly observed on suburban arterials. These issues tend to increase the risk of crash occurrence of arterials. By developing safety performance functions on road segments and intersections separately, the previous research analyzed the partial safety effects of the influence factors. In this study, Bayesian Conditional Autoregressive (CAR) models were developed at traffic analysis zone (TAZ) level for suburban arterials laid in suburban area in Shanghai. The model result showed that higher access and signal density tend to increase crash frequencies occurred on arterials. At this point, designing frontage roads paralleled to arterials to collect the access traffic instead of those intensive access could reduce crashes occurred on arterials.