FACTORS AFFECTING TRAFFIC OPERATIONS ON SEVEN-LANE CROSS SECTIONS. FINAL REPORT

Previous research has documented the operational and safety benefits of installing a two-way left-turn lane (TWLTL) on two-lane and four-lane arterials. Unfortunately, very little research has been performed to quantify the effects of seven-lane cross sections on traffic operations and safety. The goal of this research was to provide information on the factors that affect traffic operations on seven-lane cross sections in urban and suburban areas. Field studies were conducted to evaluate the effects of these factors. Acceleration noise, a measure of the relative smoothness of a trip, was used to assess the impacts of these factors on operations. Acceleration noise was collected in each lane in both directions during four periods (A.M. Peak, Off-peak, Noon, and P.M. Peak) at nine sites throughout Texas with different roadway and roadside development characteristics. From the studies, it was found that the quality of flow on seven-lane cross sections is impacted by such roadway and roadside development factors as the density of the driveways located on each side of the roadway, the average daily traffic carried by a roadway, and the average number of unsignalized intersection approaches along each side of the roadway. Generally, as the density of driveways and the amount of traffic carried on a roadway increase, the ability of the driver to maintain a trip with few changes in speed decreases. Therefore, designers should carefully consider not just the overall type of development and traffic demands on a roadway, but also the specific type of roadway and roadside development characteristics on each side of the roadway when considering implementing seven-lane cross sections in urban and suburban arterials.