By Michelle Durham

CAMDEN, N.J. (CBS) — Traffic on the bridges operated by the Delaware River Port Authority is down significantly, while those operated by the Burlington County Bridge Commission have seen an overall increase.

“We suspect a variety of factors affect bridge traffic, and right now we’re facing a perfect storm of several,” says Tim Ireland, a spokesman for the Delaware River Port Authority. “Gas prices remain high. Parking fees in Philadelphia remain high. The economy — particularly in Philadelphia’s western suburbs — remains flat. The Walt Whitman Bridge is under construction, and of course we increased tolls about a year ago.”

But Ireland says Patco ridership is up.

Liz Verna, director of communications for the Burlington County Bridge Commission, says she knows what is driving the five-percent increase in traffic on the Tacony-Palmyra Bridge:

“It’s the economy. We’re still the best bargain around. Our tolls have been at $2 since the year 2000.”

Both say the monies collected go to maintain the bridges and, in DRPA’s case, also toward the refurbishment of the Patco high-speed line’s rail cars.