Several pilot field studies were conducted to test a data collection methodology for the evaluation of AASHTO Case III-B and C sight distances for trucks at stop-controlled T intersections. The data collection plan used a combination of three traffic observation techniques: video recorders, human observers, and portable traffic data collectors. Specific findings included estimates for the gaps (time and distance) that trucks on a minor road accept during a turn manoeuvre onto a two-lane roadway, the average acceleration rate for the turn manoeuvre of a truck on a minor road, and the average deceleration rate of vehicles on a major road during a truck's turn manoeuvre from a minor road. The speed reduction by a vehicle on a major road during the truck's turn manoeuvre and the minimum separation distance between the turning vehicle and an oncoming vehicle were also estimated.
Abstract