The Santa Monica Freeway Diamond Lanes, a pair of concurrent-flow preferential lanes for buses and carpools linking the City of Santa Monica, California with the Los Angeles Central Business District (CBD), opened on March 16, 1976 and operated amid much controversy for 21 weeks until the U.S. District Court halted the project. The Diamond Lane project marked the first time preferential lanes had been created by taking busy freeway lanes out of existing service and dedicating them to the exclusive use of high-occupancy vehicles. Although the Diamond Lanes entailed no major physical modifications or construction on the freeway itself, they caused significant physical and emotional dislocation among freeway drivers, public officials and other residents of Los Angeles, and generated considerable controversy regarding the reported and actual impacts of the project. This paper summarizes the findings of the official, objective, independent evaluation of the project sponsored by the U.S. Department of Transportation as part of the UMTA Service and Methods Demonstration Program. The paper addresses a broad range of project impacts in the following major areas: traffic speeds and travel times; traffic volumes and carpool formation; bus operations and ridership; safety and enforcement; energy and air quality; and public attitudes and response. Analysis shows that the project succeeded in increasing carpool ridership by 65% and the increased bus service accompanying the Diamond Lanes caused bus ridership to more than triple. Nonetheless, energy savings and air quality improvements were insignificant, freeway accidents increased significantly, non-carpoolers lost far more time than carpoolers gained, and a heated public outcry developed which has delayed the implementation of other preferential treatment projects in Southern California and given planners and public officials in other areas ample cause for reflection before attempting to implement similar projects. /Author/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 8-16
  • Monograph Title: Recent developments in bus transportation
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00178753
  • Record Type: Publication
  • ISBN: 030902692X
  • Files: TRIS, TRB
  • Created Date: Aug 19 1981 12:00AM