The first phase of a 4-yr program on freeway merging was undertaken by the bureau of public roads to furnish more detailed information on the effect of geometric variables on merging of ramp traffic, to develop usable distributions of traffic variables for simulation programs, and to develop an optimum ramp metering and merging control system. Emphasis is on collection and collation of gap acceptance characteristics. The theoretical development of models and useful parameters for describing the merging process include the derivation of the forms of the mean and variance of the delay to a ramp vehicle in position to merge and the treatment of the variability of critical gaps and gap acceptance among drivers through the identification of the representative forms for both critical gap distributions and gap acceptance functions. Through application of individual record probit analyses, simple, statistically significant relationships between the percent gap acceptance and gap size are established. The characteristics of lags and gaps and single and multiple-entry merges are compared, as well as fast to slow moving merging vehicles. The probit analyses are generalized to establish a relationship between percent acceptance as the dependent variable and gap size and vehicular speed as the dependent variables. /author/.
Abstract