STC In The News

Bicycle Safety in Chelan, Washington from ATP and STC

TEMPE, AZ - 03/04/2014 - Solar Traffic Controls (STC) and Advanced Traffic Products (ATP) joined technologies to solve a problem for WSDOT along a stretch of winding road with a narrow shoulder. The location along Lake Chelan is popular with bicyclists during good weather.

Previously only a static sign existed to warn motorists of the conditions ahead. The warning sign now includes an amber flashing beacon, a solar-powered system and is a sensor based system to warn motorists there are bicyclists ahead on the roadway.

Dale Sanders of ATP contacted STC about the project to discuss the possibilities of using solar-powered flashing beacons with a Matrix sensor from Wavetronix as the detection method. A well-designed, solar-powered system is based on three criteria — location, load and duty cycle — consequently an analysis was done based on the projected number of activations/day in the winter.

The poor sunlight in December and the draw of the sensor made it unreasonable to run the equipment 24/7 through the winter without having an over-sized solar array. Certain key factors made the solar-based solution practical. First, with limited roadway lighting and long nights in the winter months, few bicyclists use the area after dark. Second, the area is popular with recreational cyclists; they are rarely found around Chelan in the winter when there is snow along the road so the winter activations/day are low. With these factors considered WSDOT agreed to have the system operational for only 12hours/day in the winter to cover any local users. The system is active 24/7 the rest of the year.

STC furnished a 140W SR type solar flashing beacon system. This system includes onboard control logic which allows the user to set the run time of the flasher, keep track of activation counts and perform self-test functions for the beacon sub-system. The control logic includes an LCD screen and six user interface buttons to allow adjustment of the timing parameters. Since time of day, time of year operation is also necessary, the logic control program was modified to run these functions to turn the equipment off and on. The system includes an integrated charge/flasher control unit with solid-state outputs, 15A charge control and automatic night dimming to charge the system and control the beacons. To back the system up through the winter it includes three sealed maintenance-free batteries. The DC LED lamps elements are STC model 2385C units manufactured in Phoenix, AZ. ATP furnished the Matrix sensor, a Wavetronix product, along with the support circuitry and cabling to integrate it into the STC power/beacon system.

Solar Powered Sensor Activated Bicycle Warning Flasher Chelan, WA - Solar Traffic ControlsAccording to Dale Sanders of ATP, who was present for the installation, the Matrix was configured to detect slower moving targets within the detection zone. To detect bikes and not vehicles traveling at normal speeds (35mph posted speed limit), a detection zone of approximately 10-feet in length was defined. A time delay was then programmed into the sensor output of 1.2 seconds. A target detected within the zone that stays there at least 1.2 seconds will trigger the flashing beacons.

The system was tested with a car traveling at 20mph to simulate the speed of a fast moving bicyclist on a level road. The flashing beacon triggered every time indicating it will work with slower moving bicycles also. Testing it at approximately 23mph did not trigger the beacons. Response was tested with truck traffic in the area as there was concern that their length might cause false triggering but this was not a problem. Occasionally there may be pedestrians on this stretch of road and the Matrix will pick them up. WSDOT indicated this would not be a problem since the flashing beacons would provide an added level of safety for them as well.

This project demonstrates the versatility of both the STC flashing beacon systems and the Matrix detector system to be modified to meet specific project objectives both through hardware and firmware parameter setting.

For more information on ATP and the Matrix sensor, visit For more information on STC's products and services, please stay here on our website or send an email to or call 480.449.0222.


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