County adds batteries to traffic signals to improve safety in emergencies
Rob Klug, Public Works
Vancouver, WA – Clark County is installing batteries at key traffic signals to help prevent accidents during power failures and to limit damage to equipment that could require expensive repairs.
Last week, Public Works activated battery backup systems at 13 signals in the Northeast 134th and 139th Street corridors. That includes three signals maintained by the Washington State Department of Transportation for on- and off-ramps at Interstates 5 and 205.
The backup systems are designed to allow each signal to work during power outages. Emergency battery power would support all functions, including vehicle and pedestrian detection systems.
The battery-powered signals have been programmed to operate in normal mode for two hours during a power failure. If a blackout lasts longer, signals will automatically convert to an all-red flash mode in every direction for an additional 12 to 14 hours of traffic control.
County signals typically have two to four power outages each year. Outages range from a few minutes to a few hours. Many are 10 to 45 minutes.
The battery backups will bring an added benefit of protecting signals from power surges and other situations that can damage equipment. Over time, the county plans to install as many as possible.
Battery systems cost about $4,000 per intersection. They are designed so batteries are constantly being recharged.