TIRTL

. This product is produced by CEOS Pty Ltd and marketed by CEOS Industrial Pty Ltd. It has the ability to record volume, speed, and classification on a bi-directional, multi-lane roadway. This system consists of a receiver unit and transmitter unit placed on opposite sides of the road perpendicular to the direction of travel.

The transmitter sends two cones of infrared light across the roadway and the receiver records vehicles as they break and remake these cones. The TIRTL transmitter's infrared cones cross each other and form two straight and two diagonal beam pathways. When a vehicle crosses the beam pathways, the TIRTL records two beam events; it records one from the vehicle breaking and one leaving the beam pathway. These two beams events are recorded for all four beam pathways. Thus, eight time-stamped events are generated per axle. The velocity is derived from the timestamps of these beam events.

Since the velocity of each vehicle wheel is known and a timestamp is recorded for each axle crossing each beam, the interwheel (or interaxle) spacings can be determined. Once the interaxle spacings are known, it is compared to a table of interaxle spacing ranges stored in the unit to determine the correct classification of the vehicle. The results are stored on a per vehicle basis. [cite book|title=TIRTLsoft V1.6 for Windows User Manual|pages=13|publisher=CEOS Industrial|format=PDF|edition=v1.0.1 Imperial|pages=13|chapter=Section 3.1: Vehicle Detection using 'Beam Events']

The unit has a single board computer (x486) running Debian Linux. The computer interprets the supplied traffic classification table (FHWA Scheme F or user supplied) and composes the axle events caused by the parallel beam breaks into a classified vehicle. The devices has two RS232 ports for data transfer and optional GSM & PSTN modems. The unit was originally developed to provide a verification for intersection safety cameras deployed in Victoria. [cite web| url=http://www.dpc.vic.gov.au/domino/Web_Notes/newmedia.nsf/b0222c68d27626e2ca256c8c001a3d2d/cf1d2d8ee0ccd953ca256fc7002104a3!OpenDocument
title=MORE SAFETY CAMERAS GET GREEN LIGHT|accessdate=2006-02-08|publisher=Department of Premier & Cabinet, Victoria, Australia] It was first deployed in Australia in July 1998. [cite web|url=http://www.ceosindustrial.com.au/|accessdate=2006-07-13|title=Overview of TIRTL] The unit was introduced to the North American market during the 2004 NATMEC (North American Travel Monitoring Exhibition & Conference) and first deployed in May 2006.

The TIRTL was reviewed by the Minnesota Department of Transportation. They, in conjunction with 16 participating state DOTs, conducted a pooled fund study called PNITDS (Portable Non-Intrusive Traffic Detection System). The final report stated that the TIRTL correctly classified 94% and 97% of the total vehicles polled. [cite paper|title=Evaluation of Portable Non-Intrusive Traffic Detection System|url=http://www.dot.state.mn.us/guidestar/pdf/pnitds/final-report.pdf|format=PDF|publisher=Minnesota Department of Transportation, Research Services Section|accessdate=2006-06-20|author=Kotzenmacher, Minge, et al.]

References

ee also

*Road traffic control
*Traffic counter

External links

* [http://www.tirtl.com Official website in the US]
* [http://www.ceos.com.au/products/tirtl.htm Manufacturer's website]
* [http://www.pooledfund.org The Federal Highway Administration's Transportation Pool Fund Program website]
* [http://www.dot.state.mn.us/guidestar/ Minnesota Department of Transportation's Guidestar program.] - The umbrella project under which the PNITDS project was undertaken.