Development of a Non-Intrusive Axle Detector

The Kentucky Transportation Cabinet's Division of Planning collects traffic count data on a wide range of roadways from very low volume to very high volume. This data is used for highway design, FHWA submittal, traffic signal timing, etc. Although traffic data collection at low volume locations is in itself hazardous, collection of this data at high-volume, high-speed locations is sometimes impossible using existing methods. If the technician is able to install the road tube, impact from the many axles striking the tube causes the tube to roll back and forth in the traffic stream. Many times the result of this rolling action either wears the road tube out causing it to break or causing the road tube to detach from the roadway. The loose road tube is then free to be carried up and down the pavement by the traffic stream causing another hazardous condition to vehicles and even pedestrians if present. The Division of Planning has responded to this condition in certain situations by installing induction loops in the roadway at many high-volume locations. The cost of installation, maintenance, and replacement is very expensive and with construction and resurfacing projects ongoing, many times the sensors are destroyed and must be replaced. Another solution to the problem of traffic data collection at high-volume locations is the use of wide-beam radar. These radars must be positioned above the roadway and a ladder or bucket truck must be used, which again exposes the technician to hazardous conditions. There are also occasions when traffic data needs to be collected at a specific location at a specified time. There would be no reason to install permanent sensors in this situation. For these reasons the Kentucky Transportation Cabinet, Division of Planning has requested the Kentucky Transportation Center to investigate and evaluate the development of a non-intrusive axle detector. This detector should be designed to sit safely off the roadway and be able to detect axles in up to four (4), 12-foot wide, high-volume, high-speed lanes. The equipment must be easy to set up, be robust, battery powered and have a contact closure-type output to enable connection to a portable traffic data recorder. The Kentucky Transportation Center will utilize Spectra Research, Inc. of Dayton, Ohio in the development of two prototype units specifically for this purpose. Spectra Research has had proven success with a laser radar (LADAR) device that was developed for the Ohio Department of Transportation, (ODOT). This device contains two (2) sensors spaced one foot apart in a single unit. The unit the Kentucky Transportation Cabinet desires is, for the most part, a single sensor version of the unit that was developed for ODOT. Differences will include a smaller sensor package with the sensor head being separate from the power and processing unit. This functionality will make the unit less conspicuous to passing motorists. The Kentucky Transportation Center will evaluate the effectiveness and efficiency of the non-intrusive axle detector developed by Spectra Research in conjunction with the Division of Planning. The evaluation will involve observing the assembly of the non-intrusive axle detection unit and collecting data at a location(s) where the Division of Planning has permanent, conventional equipment installed. These sites will be pre-selected by the Kentucky Transportation Center and the Division of Planning. The collected information will be analyzed and the findings submitted in a report prepared for the Division of Planning.