Cumulative inter-arrival time (IAT) distributions for signalised and non-signalised freeway entrance ramps were developed to be used in digital computer traffic simulation models. The data from four different non-signalised entrance ramps (three ramps with a single lane, one ramp with two lanes) and two different signalised entrance ramps (both with a single lane) were used for developing the cumulative IAT distributions. The cumulative IAT distributions for the signalised and non-signalised entrance ramps were compared with each other and with the cumulative IAT distributions of the lanes for freeways. The comparative results showed that the cumulative IAT distributions for non-signalised entrance ramps are very close to the leftmost lane of a 3-lane freeway where the maximum absolute difference between the cumulative IAT distribution of the leftmost lane of a 3-lane freeway and the entrance ramps cumulative IAT distribution was 3%. The cumulative IAT distribution for the signalised entrance ramps was found to be different from the non-signalised entrance ramp cumulative IAT distribution. The approximated cumulative IAT distributions for signalised and non-signalised entrance ramp traffic for any hourly traffic volume from a few vehicles/hour up to 2,500 vehicles/hour can be obtained at http://www.ohio.edu/orite/research/uitds.cfm. (Author/publisher)
Abstract