All FRWS Sites
The Flooded Roadway Warning System is made up of three components:
The sensor monitors the elevation of a nearby stream and reports any change, every three minutes, to the central computer.
When flood water reaches the edge of the roadway, a float switch tells the sensor to signal the sign to change to the warning text and turn on the flashing lights. The sign sends a message back to the sensor confirming that everything is working properly. The sensor radios all this information back to the central computer. Emails are sent to staff and the appropriate Street Services district alerting them of the need to place barricades at this location as soon as possible.
The signs and sensors are battery powered and recharged with solar cells or backup electric service. All communication between the sensors and signs and sensors and the central computer are by radio.
The sensors normally control the signs without intervention from the central computer. However, the central computer can issue commands to turn on the signs and lights.
The signs include changeable text messages and red flashing lights. In the non-alarm state, the lights are off and the sign shows High Water When Flashing. In alarm state, the lights alternate flashing and the sign changes to Do Not Enter High Water. The signs and lights are equipped with sensors to detect the status.