This report addresses the broad technical objectives on the Single Point Urban Interchange (SPUI). Information is provided on the historical development of SPUIs, typical geometric and bridge design, observed traffic operations, and general traffic engineering applications. In particular, the report presents a wide variety of statistical summaries of geometric and operations data collected for 36 SPUIs, most of which were observed during a field survey of SPUI operations in 13 states conducted during the summer of 1989. Following a synthesis of these data, geometric and operational guidelines are provided for informational purposes, because there are no specific guidelines on the interchange in the 1990 AASHTO Green Book. Advantages and disadvantages of various SPUI design features are given. The report also contains guidelines for conducting cost-effectiveness studies of the SPUI as compared primarily to the Tight Urban Diamond Interchange (TUDI). A recommended methodology is presented and special SPUI features are identified for which local cost estimators might not be familiar. Updated operational user benefits estimation procedures are also given. The report concludes with a summary of research findings and recommended application guidelines for SPUIs as being a viable competitor to the TUDI for congestion relief in restricted urban conditions. In this context, the SPUI was found to be a safe and efficient interchange design alternative. (A)
Samenvatting