Citizens for Appropriate Transportation (CAT)
The Eisenhower Transportation Corridor

HOV LANES - A PRIMER

What is an HOV lane? A High-Occupancy Vehicle Lane is a car pool lane. For the Eisenhower Corridor, the Illinois Department of Transportation (IDOT) proposes adding one HOV lane each way from Austin Boulevard to Mannheim Road. At present, there are no HOV lanes in Illinois.

Are there HOV lanes elsewhere? There are about 96 HOV freeway projects in 30 metropolitan areas, including Dallas, Houston, Los Angeles, San Francisco, Seattle, and Washington D.C.

What is the theory behind HOV lanes? With more people in each vehicle, there are fewer vehicles needed to reach the same capacity. If each vehicle in an HOV lane carries three people, then the lane can have one-third as much traffic as a general traffic lane and still have the same people-carrying capacity. With fewer vehicles in the HOV lane, travel time will be reduced.

What are HOV lanes supposed to do?

  • Decrease travel time
  • Increase the capacity of a freeway
  • Decrease air pollution

What are the differences among HOV projects? Three major differences among HOV projects are:

  1. Do they allow all vehicles or buses-only?
  2. Are they full-time or part-time (peak hours only)?
  3. Do they have painted stripes or barrier separation from general traffic lanes?

IDOT's 1998 study for the Ike recommended HOV lanes that allow all vehicles, full-time HOV lanes, and four-foot painted buffers between the proposed HOV lanes and the general traffic lanes.

Have any HOV lanes been discontinued? Yes. In November 1998, New Jersey Governor Christine Whitman discontinued the HOV lanes on I-287 and I-80 because they did not encourage carpools, reduce congestion, or reach a minimum of 700 vehicles per hour.

In New York, Governor George Pataki canceled plans for carpool lanes on the Cross Westchester Expressway and Long Island Expressway.

Some people claim that HOV lanes are just a trick to build more roads. Are they right? The scenario that they see is that HOV lanes are built for good-sounding objectives. If they don't work, they become general traffic lanes.

IDOT wants to test HOV lanes, but selecting the Eisenhower Expressway as the test is a strange and expensive choice. IDOT needs additional right-of-way for the HOV lanes and must rebuild every intersection. In contrast, the express lanes on the Kennedy and Dan Ryan Expressways could be converted to HOV lanes just by changing the signs and adding pavement markings.

Further, the HOV lanes on the Ike would stop at Austin Boulevard rather than continuing all the way into the Loop, reducing their effectiveness.

The phenomenon of "induced demand," (adding roadway capacity induces more people to drive) is also a concern. IDOT spent $140 million and two years on the Hillside Strangler improvements only to see travel times remain about the same (Chicago Sun-Times May 16, 2002). See our September 2002 Issue Brief #4 on Induced Demand for more details.

Don't HOV lanes require a lot of management? Yes they do. HOV lanes don't work with either too much traffic or too little traffic. Too much traffic means longer trip times so the objective of reducing travel time is not met. Too little traffic creates the "empty lane syndrome" where the capacity of the HOV lane is underutilized and more congestion and longer travel times occur on the general traffic lanes.

Are car pools hard to form? People who work late or irregular hours, use their cars during the day, park free at work, have young children or aging parents, and who need to run errands during their commute are less inclined to car pool.

Is there an unbiased study on HOV lanes? A report by the nonpartisan Legislative Analyst’s Office in California said: "Based on our review of available data, we conclude that the performance of HOV lanes is mixed."(HOV Lanes in California: Are They Achieving Their Goals?) The report continues:

  • HOV lanes in California operate at only two-thirds of their capacity.
  • The impact of HOV lanes on air quality is unknown because documentation is based on models and projections rather than actual emission data.
  • HOV lane use does not necessarily increase over time, contradicting the theory that people form car pools to take advantage of them.

CONCLUSION: IDOT has not made the case for why they want to spend $800 million to test HOV lanes on the Ike rather than spend virtually nothing to test HOV lanes on the Kennedy or Dan Ryan. If the purpose of the proposed Ike expansion is to increase roadway capacity, then they must prove that HOV lanes will work and are better than alternatives such as extending the CTA Blue Line, upgrading the Metra commuter rail lines, and alternatives that include all modes of transportation.

Rick Kuner - October 2002

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