Daylight-saving time fools school-zone lights

Published 6:01 pm Friday, October 30, 2009

If daylight-saving time gives you fits, you’re not alone. The time-shifting practice tricked some of the flashing school-zone signs in Bellevue this week, causing the lights to go on off-schedule.

A resident on Wednesday noticed that the signals at Sherwood Forest Elementary failed to blink while students were walking home during early dismissal, but the lights turned on an hour later when the children were gone.

The error was due to a change in the day that daylight-saving time switches back to standard time. From 1986 to 2006, the shift took place on the last Sunday in October. But the federal government changed that date to the first Sunday of November in 2007.

Since then, “daylight time” has been observed from the second Sunday in March to the first Sunday in November. Overall, this change added about a month to daylight-saving time.

The city never updated its flashing-light controller at Sherwood Elementary to match the adjustment, so the signals went off as though the time shift occurred the previous Sunday.

The transportation department has since corrected the problem, and is working toward establishing a communication link to the controller from the traffic-management center at City Hall.

Two other errors have occurred this year with Bellevue’s school-zone lights, according Mark Poch, a traffic engineer with the city.

At Stevenson Elementary, a sign did not turn on at the correct time because of a scheduling error input into the controller.

Another problem occurred with one of the signals at Sherwood that came on inadvertently in the evening. This was due to a concern with the radio signal between the sign and the controller, according to Poch.

Transportation department spokesman David Grant said the city relies on input from residents to monitor its flashing lights.

“Much like the police department depends on citizen tips and involvement to make Bellevue a safer place, the transportation [department] depends on people who use the city’s street system on a regular basis to help keep us apprised of potential problems,” he said.

Poch said the city cannot at this point monitor all of its flashing lights from the traffic-management center at City Hall.

Joshua Adam Hicks can be reached at 425-453-4290.