IB-2003-D (July 2003)
Author: Jon Caldara
Background: HOV Falls Short
“This idea will solve traffic congestion permanently.” No credible transportation official ever seems to say this anymore. Certainly, many will imply that the latest transitfad will somehow, magically reduce traffic and congestion, but they know that no investment will ever solve congestion.
Nonetheless, in many U.S. urban areas congestionfree options do exist. Twenty years ago, High Occupancy Vehicle (HOV) lanes, or carpool/ diamond lanes as they are often called, were the transit-fad that led to these congestion- free trips. These are lanes separate from the normal “general-purpose” lanes of travel, often providing many miles of reserved laneage, for those who carpool or ride the bus. Provided you carpooled, you would enjoy a congestion-free trip on the HOV lanes.
The HOV advocates imagined that ordinary commuters would flock to carpools and buses, doing anything to escape the horrors of traffic; the increased carpooling and bus riding would benefit everyone, with lower pollution, decreased congestion, and reduced stress.
Somewhere between wish and reality, things didn’t work out so well. Although HOV lanes are relatively successful at moving people (at least in HOV lanes oriented towards central business districts), many of the HOV users are people who simply moved from the general purpose lanes to the HOV lanes. To make matters worse, carpooling has declined dramatically nationwide since HOV lanes were widely implemented.1 It seems the convenience of the personal automobile still warranted putting up with the horrors of traffic and congestion. An Alternative: Merging Toll Roads with HOV Lanes There may, however, be a way to guarantee that a driver would always have the choice of making an uncongested trip without changing to a carpool or riding the bus. Offering this option to drivers can also provide the same congestion-free benefit to carpoolers.
HOV lanes currently feature “unused space,” or as transportation planners refer to it, “excess capacity.” The Reason Public Policy Institute studied HOV systems in various metropolitan areas and found that the typical HOV lane nationwide has 950 vehicles per hour and 2275 persons per hour. Although the total number of persons per hour is generally higher than in the adjacent general-purpose lanes (2000 persons per hour on average for a congested lane), the HOV lanes could carry 45 percent more vehicles and still flow at 55 miles per hour. This ability to carry 750 more vehicles per lane is typical of HOV lanes’ excess capacity.