Over Height Vehicle Detection Systems (OHVDS) identify and warn incoming traffic that is too tall, in situations where the maximum height of vehicles is restricted.

Typical Use Cases

  • Bridges
  • Overpasses
  • Railroad tunnels
  • Tunnels
  • Temporary Falsework
  • Airport passenger drop-off, overhangs and pedestrian walkways

How Does It Work?

Over Height Vehicle Detection System Concept

Over Height Vehicle Detection Systems make use of raised sensors positioned perpendicular to the roadway some distance in front of the low clearance target. When these sensors detect a vehicle that is too tall to pass under safely, linked warning signs and/or audio alarms are triggered to warn the driver that their vehicle is too tall, and provide them with some way to get around the problem; i.e. exit to the right, turn around, etc..

Over Height Vehicle Detection System Concept

Site Selection Considerations

When constructing an Over Height Vehicle Detection System, there are many parameters that must be evaluated first:

  • What is the posted and practiced speed limit at the installation site?

    Vehicle speed determines (in part) the distance from the detector the warning sign must be placed to provide sufficient time for drivers to react to directions given.

  • What exits, pull-offs or U-turns are available between the detector and obstruction?

    Availability of such options must be taken into account as courses action for over height vehicle drivers and directions given to them accordingly.

  • Will the detection system monitor one-way or two-way traffic across the roadway?

    Determines whether system must be direction discerning.

  • What is the number of lanes in the direction of interest?

    May further determine distance required between detection and warning sign/exit if lane changing is involved.

  • What is the height of the obstruction (clearance required) and is there the same clearance for each lane.

    The shape and/or contour of the obstruction or roadway may require more than one Over Height Vehicle Detection Systems (OHVDS) to monitor multiple heights or axis.

  • Are there any weather or airport radars within ¼ mile of the Over Height Vehicle Detection Systems (OHVDS) installation site?

    Since both the Visible Red and Infrared detectors are made from silicone substrate, it may be possible to generate a false alarm if the detector is looking directly into the radar.

  • What will be the smallest sun angles encountered with respect to the detector’s site?

    The Visible Red detectors need a 3 degree clearance from direct sunlight and the Infrared detectors require an 8 degree clearance.

  • Is there 115 VAC power available on both sides of the road at the installation site?

    If AC power is not available, solar power may be an option. There can be a combination of both AC and solar power within the same system if necessary.

  • What is the desired alarm time?

    This is the cumulative time requirement considering speed, distance, number of lanes and required driver response. Our systems offer 1-30 seconds, 5-60 seconds all standard feature and custom times up to five minutes at no additional charge.

  • Is remote reporting of an over height detection and/or fault condition required?

    If so, this requirement dictates choice of system.

  • What are the local traffic patterns?

    These may influence directions given to drivers in over height situations.

  • Is camera monitoring or image capture required?

    Mounting requirements and angle of view must be taken into consideration.