MAIN ROAD 3 CAPACITY STUDY

The vehicle type, complete licence number, and passing time were recorded for a total of 33400 vehicles at four points on a two-lane main road in southern Finland. The travel speeds of vehicles were computed for each of three road sections, 20-30 km in length, totalling 75 km. The with-flow hourly volumes varied from 200 to more than 1200. The relationship between with-flow hourly volume and mean travel speed was linear at each section up to the highest volumes. On the whole 75-km stretch, mean travel speed of passenger cars decreased 9 km/h with increasing the volume by 1000 vehicles, as far as only those cars were considered which did not stop on the way. This means that less than 5 min time is lost on the whole section when the traffic volume increases from free conditions of 200 veh/h up to almost continuous platooning at 1200 veh/h. But if the stops for gasoline and coffee (5-25 min) are included, the lost time is only 1 to 2 min (3 km/h) decrease in travel speed for 1000-veh increase of flow. (TRRL)