University Drive Overpass Site
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| University Drive overpass sensor site looking north
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The Site
The University Drive overpass is currently our northern most detector station. At this point the rail line encounters Bryan Siding. Bryan siding is used heavily by the railroad to meet opposing trains or have a higher priority train pass a low priority train. The University detector is positioned at the south end of Bryan siding. Train speeds can vary between 30 mph all the way down to just a few miles per hour. The radar at this site will need to be able to detect very low speeds. This requirement is one that traditional traffic radars are not specifically designed to meet. Our equipment is installed on a nearby City of College Station traffic signal pole and can detect trains moving on either the siding (rightmost track) or the main line. Directly behind the photographer the rail line passes over University Drive. This is the only grade separated crossing in the corridor and of great importance for future research in route planning.
Equipment
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| TC26-S radar sensor and 900MHz antenna
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The radar chosen for this site is the Microwave Sensors TC26-S model. The detector supplies a speed every half second to the field controller. The radar was modified by TTI to have its direction sense remotely controlled. Communication for the site is supplied by a 900MHz data radio system linked to the TransLink TMC via the corridor repeater. A 6dB yagi antenna was chosen for the site. Note the fact that the yagi antenna is positioned above the traffic signal pole on a plastic mast. Placing the antenna on the metal traffic signal pole can produce a major shift in antenna characteristics.
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| The pole box installed at Univeristy Drive
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The interior of the box reveals the componets of our rail detection system. On the bottom right is a 12Vdc power supply that provides energy for all the equipment. Above the power supply is a terminal strip used for terminating and connnecting all wiring. Above the termimal strip is the field controller. Each field site uses a BASIC Tiger from Wilke Technology as the processing core. The controller accepts a serial stream from the radar containing speed data, manages the radar direction sense and interfaces with the data radio (on the left). As can be seen, the system is very compact and can easily be installed in a much smaller enclosure.
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06/28/2000