By Pat Loeb

PHILADELPHIA (CBS) — Crowds are descending on Philadelphia just at the worst time of year for city streets. Winter damage has not yet been repaired, but relief is in sight.

Moisture and temperature changes combine to create potholes all winter, but it also means repairs to one of the biggest street damage problems– plumber’s ditches– are only temporary.

Chief Engineer Steve Lorenz says the Streets Department has been waiting for this mild weather to make them permanent.

Lorenz says those ditches are actually a good sign for the city. They often accompany new construction.

Contractors get a $550 permit to dig up the street to put in infrastructure for new buildings. That pays for repairs later.

Lorenz says some plumbers try to get around that, so he urges residents to call 3-1-1 if they see a street being dug up so the city can be sure it’s been permitted.