NCHRP Research Results Digest 247, "The Relationship Between Access Density and Accident Rates: Comparisons of NCHRP Report 420 and Minnesota Data," provides additional support for the relationships presented in NCHRP Report 420, confirming that accident rates rise as access density rises. NCHRP Report 420, "Impacts of Access-Management Techniques," was produced by NCHRP Project 3-52.

This project also produced draft language related to access management that was considered by AASHTO in the development of the 2001 edition of A Policy on Geometric Design of Highways and Streets.