• KYW News 4:30-7am
    04:00 AM - 07:00 AM

By Mike Dunn

PHILADELPHIA (CBS) — If you’ve been stuck in Philadelphia traffic this week because of balky, cold-bitten traffic lights, you’re not alone.

The city has thousands of traffic signals and most are old and mechanical, and therefore likely to falter when the temperatures plummet.  City officials say that traffic signals that are less prone to breakdown are planned — but a long way off.

Streets commissioner David Perri says this week’s cold was particularly rough on the signals.

“Typically in the wintertime we would expect about four or five traffic signals to be affected by the cold weather,” he tells KYW Newsradio.  “On Tuesday we were in the mid-30s: we had over 30 traffic signals affected by the cold.”

The reason, Perri says, is that when the mechanical switching mechanisms get wet, they freeze.

“When moisture gets inside of these older traffic signal boxes and the temperatures drop quickly, they freeze up inside, causing problems with the signals,” he explains.

Change is coming, according to Perri, as the city moves to solid-state signals that are less vulnerable to cold conditions.

“We are gradually changing over our signals to electronic, and doing away with our older, electro-mechanical traffic signals.  And as time goes by, it will become less and less of a problem.”

But that changeover is manpower-intensive, and the streets commissioner says a complete overhaul of the city’s antiquated traffic signals is still a decade out.

“I would say it’s probably about ten years,” he acknowledged.

And Perri notes that Wednesday’s huge traffic signal problem at the top of the Schuylkill Expressway ramp to 30th Street Station was not caused by the cold, but rather by of an interruption of power to the signal.

He says they’re still trying to find the precise source of that outage (see previous story), and they are considering installation of a backup battery at the signal.

The signal itself, according to Perri, is one of the newer, solid-state ones.

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