A study of traffic capacity was conducted by Bruce D Greenshields, Research Engineer, Traffic Bureau, Ohio State Highway Department. The study, initiated in June 1934, aimed to determine the traffic capacity of a two-lane roadway and the amount of vehicle time lost under varying degrees of congestion. Data were collected using a photographic method described in the Proceedings of the Highway Research Board, Vol 13. The data were analyzed to determine the working capacity of a two-lane roadway and the effects of congestion on traffic speed. The study involved 1180 groups of 100 vehicles each, with no more than 10% trucks. The average free-moving speed was found to be about 43 miles per hour on either a two or three-lane road. When the number of vehicles exceeded 400 to 600 per hour, the average speed decreased. The mean speed of 859 light trucks was 41.0 miles per hour, and of 225 heavy trucks, 32.4 miles per hour. For 18 buses, the average was 41.6 miles per hour. The study also analyzed the distribution of vehicle speeds and the relationship between speed and density. The data showed that as the density on a two-lane roadway increases beyond 400 to 600 vehicles per hour, the average speed of all vehicles decreases. This loss of speed is a measure of the congestion or loading of the roadway beyond its free carrying capacity. The study also found that the average free speed on uncongested roads was approximately 43 miles per hour, with the percentage of trucks varying from zero to ten. The study also examined traffic on various roads, including US 6, US 20, and US 23, and found that the average free speed was around 43 miles per hour. The study also derived an equation for expressing the relationship between speed and density, which was used to estimate the time lost due to congestion. The study concluded that the average free-moving speed of vehicles on a first-class roadway in dry weather with the percentage of trucks varying from zero to ten is very nearly constant and equal to approximately 43 miles per hour. The study also found that the speed range of light trucks was between 20 and 50 miles per hour, while the speed range of heavy trucks was between 20 and 50 miles per hour. The study also found that the average free speed of 18 buses observed was 41.6 miles per hour. The study also found that the mean "smoothed" speed of 859 light trucks was 41.0 miles per hour, and of 225 heavy trucks, 32.4 miles per hour. The study also found that the speed range of light trucks taken from a normal probability curve was as followsA study of traffic capacity was conducted by Bruce D Greenshields, Research Engineer, Traffic Bureau, Ohio State Highway Department. The study, initiated in June 1934, aimed to determine the traffic capacity of a two-lane roadway and the amount of vehicle time lost under varying degrees of congestion. Data were collected using a photographic method described in the Proceedings of the Highway Research Board, Vol 13. The data were analyzed to determine the working capacity of a two-lane roadway and the effects of congestion on traffic speed. The study involved 1180 groups of 100 vehicles each, with no more than 10% trucks. The average free-moving speed was found to be about 43 miles per hour on either a two or three-lane road. When the number of vehicles exceeded 400 to 600 per hour, the average speed decreased. The mean speed of 859 light trucks was 41.0 miles per hour, and of 225 heavy trucks, 32.4 miles per hour. For 18 buses, the average was 41.6 miles per hour. The study also analyzed the distribution of vehicle speeds and the relationship between speed and density. The data showed that as the density on a two-lane roadway increases beyond 400 to 600 vehicles per hour, the average speed of all vehicles decreases. This loss of speed is a measure of the congestion or loading of the roadway beyond its free carrying capacity. The study also found that the average free speed on uncongested roads was approximately 43 miles per hour, with the percentage of trucks varying from zero to ten. The study also examined traffic on various roads, including US 6, US 20, and US 23, and found that the average free speed was around 43 miles per hour. The study also derived an equation for expressing the relationship between speed and density, which was used to estimate the time lost due to congestion. The study concluded that the average free-moving speed of vehicles on a first-class roadway in dry weather with the percentage of trucks varying from zero to ten is very nearly constant and equal to approximately 43 miles per hour. The study also found that the speed range of light trucks was between 20 and 50 miles per hour, while the speed range of heavy trucks was between 20 and 50 miles per hour. The study also found that the average free speed of 18 buses observed was 41.6 miles per hour. The study also found that the mean "smoothed" speed of 859 light trucks was 41.0 miles per hour, and of 225 heavy trucks, 32.4 miles per hour. The study also found that the speed range of light trucks taken from a normal probability curve was as follows