A STUDY OF NO-PASSING ZONE CONFIGURATIONS ON RURAL TWO-LANE HIGHWAYS IN NORTH CAROLINA: VOLUME II

For the roadway designer interested in making selective passing sight-distance improvements on a section of a two-lane, two-way rural highway, there is no satisfactory technique to evaluate the traffic flow consequences of these individual improvements. For this reason, a study was undertaken to investigate the relationships between the independent variables of percent of the total length of a section of highway marked with no-passing barriers and the traffic volume input to the section of highway, and the dependent throughput variables of mean speed change cycles. Multiple linear regression equations and graphs are developed for the variables. The conclusions are that a digital computer model for traffic simulation can be employed to represent and duplicate traffic flow on two-lane, two-way rural highways, and that such a model, once calibrated for specific traffic flow characteristics, can provide the highway designer with detailed information on the traffic consequences of small changes in the percent no-passing zone barriers. While the regression equations and graphs are dependent upon North Carolina data, the methodology used is generally applicable to two-lane, two-way rural sections of highway approximately five miles long, with two-way volumes between 200 and 1,200 VPH, any directional distribution of two-way volumes, any percent of medium trucks, any percent of heavy trucks, vertical grades not greater than plus 8 percent nor less than minus 8 percent and little or no side road traffic volume. /FHWA/