Development of Improved Guidelines for Frontage Road Driveway Access at Entrance211 Ramp Locations

摘要

This report documents procedures and results associated with the development of211u001eimproved guidelines for driveway to entrance ramp spacing along freeway frontage 211u001eroads. The analyses utilized in this research consisted of operational and 211u001ecrash/safety assessment-both of which were based upon field data specifically 211u001ecollected as a part of this research project and/or historical data. Several 211u001elocations in the San Antonio and Austin, Texas, areas were utilized as field 211u001esites in this study. The results of the research indicate that an adoption of new 211u001e'desirable' guidelines should be pursued to accompany the current guidelines-the 211u001elatter of which it is suggested be retained as 'absolute minimum' spacing 211u001eguidelines. The new 'desirable' guidelines serve to double the distance in 211u001eexisting guidelines in relation to both upstream and downstream placement of 211u001edriveways in relation to entrance ramps. This change specifically entails going 211u001efrom an absolute minimum of 100 feet to a desirable spacing of 200 feet upstream 211u001eof the ramp and an absolute minimum of 50 feet to a spacing of 100 feet 211u001edownstream of the ramp.