Citation

Windover JR, May AD. Transp. Res. Rec. 1994; 1457: 43-49.

Copyright

(Copyright © 1994, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

For ramp weaves on an eight-lane freeway, the total point flow method has been demonstrated to predict point flows in each of the rightmost two lanes more accurately than the Level D methodology. The Level D methodology is one of the current methods used by the California Department of Transportation (Caltrans). Research undertaken at the Institute of Transportation Studies at the University of California, Berkeley, improved the Level D estimates of point flow for weaving sections operating under various flow ranges. The Level D estimate of freeway-to-freeway (FF) percentage in the rightmost through lane was modified to improve the point flow predictions. An equation was developed that predicts the FF percentage as a function of weaving section length, upstream section demand, on-ramp demand, and off-ramp demand. The process involved a calibration effort that compared total point flow and Level D estimates of volumes in the rightmost through freeway lane. From this comparison an FF percentage estimating equation was developed that, when incorporated in Level D, would result in Level D producing volume estimates comparable in accuracy to the total point flow method. It was validated with the empirical data that were used to develop the total point flow method. The FF estimating equation used with Level D produced significant improvements in the point flow prediction. The equation is recommended for inclusion in the Level D methodology incorporated in FRELANE.

Record URL:
http://onlinepubs.trb.org/Onlinepubs/trr/1994/1457/1457-005.pdf

Language: en

Keywords

Calibration; Highway engineering; Estimation; Computer simulation; Motor transportation; Highway systems; Numerical methods