Traffic Management > Lane Control System               Printer-friendly version

Lane control signals (LCS) have been or are currently being installed on freeways in several major metropolitan areas in the United States. Consisting simply of overhead lane specific signals denoting a red "X" if travel in the lane is prohibited, and a green arrow if travel is permitted, these signals symbolically display the current status of each freeway lane to inform motorists of the condition of the lanes downstream so that they may take appropriate action. See our Telecommunications Diagram on Lane Control for more information. LCS have been in existence for over 30 years, and are more common outside the United States.  Historically, the most prevalent use of LCS has been for the operation of reversible lanes. Some of the benefits associated with LCS implementation include:

• reduction in the number and severity of primary and secondary accidents;
• improved traffic flow stability (less variation in vehicle speeds) headway optimization, and increased vehicle throughput;
• reduced travel time, energy consumption, and pollutant emission;
• reduced queue lengths;
• improved safety and efficiency for roadway maintenance operations;
• improved emergency vehicle movement.

Where is it Implemented?

Brisbane, Australia
One of the most sophisticated Lane Control Systems (LCS) implemented to date exists on Coronation Drive in Brisbane, Australia. Coronation Drive is a major inner city arterial and passes through a large business and residential area. There are many buses running along this Drive that have to run in the curb lane at all times. As a result, a lane control system was needed--beyond an HOV lane--that would allow buses to travel quickly on the appropriate side of the road during different times of day. The currenlty installed Coronation Drive Tidal Flow system advises motorists entering the road of which lanes they may drive in at various times of day. This system works through the integration of a number of technologies:

• LED displays over each lane indicate which lanes are open or closed
  • Changeable Message Signs (CMS) that display a straight-ahead arrow, left turn arrow, or right turn arrow indicate to motorists that the lanes bearing such signs are open. CMS that display a red cross indicate that a lane is closed.
• Electronically-controlled barriers prevent drivers from entering a closed lane. A controller can remotely open or close as well as monitor the status of the barriers. A beacon is positioned on a barrier post and flashes when the barriers are opening or closing.
• Pavement lights embedded in the roadway direct traffic away from the bus lanes during peak hours.
• Loop detectors sense the persistant presence of a vehicle traveling in the opposite direction in a particular lane; this results in the closure of the lane and the opening of the lane for traffic in the new direction.
• Lane control computers control each device in this system. These computers monitor and activate the lane control devices during transition periods (i.e. when traffic must be directed towards lanes outside the main arterial)

Other Field Test Results of LCS Systems

Area	Benefits	Source
Minneapolis, MN (I-94 system)	Lane volumes upstream of congestion reduced 7 to 11 percent.	Carlson, G., A. Lari. Evaluation of the use of downward Yellow Arrows in the I-94 Lane Control Signal System. Minnesota Department of Transportation. August 1982.
Austin, TX	7 to 12 percent reduction in the lane volumes at various points upstream of an incident.	Burford, W. A Study of the Effectiveness of a Changeable Message Sign System. Teas Section, ASCE Department of Civil Engineering. University of Texas at Austin, January 1983.
Detroit, MI (Lodge Freeway)	Minimal effect on freeway throughput and lane changing activity, but did encourage drivers to exit the closed lanes.	Dudek, C. Freeway Traffic Surveillance and Control Research Project: Study 424 - Effect of Incidents on Freeway Traffic. Michigan State HIghway Department
Netherlands-(Dutch Motorway Control and Signaling System)	16 percent total accident reduction;   36 percent reduction in secondary accidents;   19 percent reduction in the number of vehicles involved in accidents.   42 percent reduction in roadway work in the day;   25 percent reduction at night	Klijnhout, I. Motorway Control and Signalling: The Test of Time". Traffic Engineering and Control. Volume 25, No. 4, April 1984.
Glasgow- (CITRAC-Centrally Integrated Traffic Control)	20 percent reduction in off-peak accidents during its first five years in operation	Mowatt, A. CITRAC-The First Five Years. Traffic Engineering and Control. Volume 25 #5.1984.

Authors: Lauren Smith, Justin Black, and Joe Wanat.  Last update: 7/16/02