California Partners for Advanced Transportation Technology

This is the most extensive empirical evaluation of the effectiveness of California’s HOV system based on data collected from traffic sensors. The evaluation leads to four major conclusions. (1) Since it operates as a single lane freeway, an HOV lane suffers a 20 % capacity loss compared with multi-lane freeways. (2) HOV lanes are either under-utilized or suffer degraded operations. (3) HOV lanes do not measurably increase car-pooling. (4) HOV lanes do not reduce overall congestion in a reasonably well-managed system.