An expected midnight reopening of the severed I-95 has been put off until 5 a.m. tomorrow, a PennDot official said late tonight.

PennDot spokesman Gene Blaum said the crew putting up four support towers to buttress a compromised section of the freeway at Richmond and Cambria Streets in Port Richmond encountered some unexpected problems.

Workers erected four steel towers to take the weight off the pillar and support the highway, but PennDot had to add eight steel plates called "stiffeners" to the bottom of the elevated highway.

That forced a delay of the scheduled midnight opening.

"It's an additional safety measure that's part of the design process," Blaum said.

The latest plan called for testing the roadway about 4 a.m. tomorrow, he said.

Eight trucks loaded with salt will be driven over the roadway, to check for any unwanted settlement or vibrations. They'll also be stopped directly over the newly reinforced area, so the bracing can be calibrated to handle stopped as well as moving traffic.

If the roadway passes the salt-truck test, I-95 could be reopened within an hour, about 5 a.m.

All this comes on the heels of another troublesome day for motorists who rely on I-95.

SEPTA today added more cars to the R7 line this morning to handle extra passengers, but ridership wasn't unusually heavy, according to spokesman Felipe Suarez.

"We just didn't see a significant increase," he said.

Motorists seeking an easy-to-follow alternative within the city could try the Schuylkill Expressway (I-76) and Roosevelt Boulevard (Route 1).

Another option is to jump over to New Jersey. Northbound motorists can take the Walt Whitman or Ben Franklin bridges to Route 130 North and then come back over the Tacony Palmyra Bridge or the Betsy Ross.

Southbound drivers can try the reverse.

The other option is to simply brave the detours around the I-95 shutdown, which take vehicles on smaller Port Richmond streets that have been getting clogged.

According to PennDot, "the detour for conventional cars and SUVs traveling north on I-95 is to exit at Girard Avenue (Exit 23), bear left onto Aramingo Avenue and follow Aramingo Avenue to the on-ramp to I-95 North near Church Street."

"The detour for conventional cars and SUVs traveling south on I-95 is to exit the interstate at Betsy Ross Bridge/Aramingo Avenue (Exit 26), turn right onto Aramingo Avenue to the ramp at the Girard Avenue Interchange."

Truckers were being detoured at either I-676 or Woodhaven Road for a circular route involving the Schuylkill Expressway and Roosevelt Boulevard.

The four support towers, needed to brace a section of the highway around a severely cracked pillar, were rushed in from Baltimore, Pittsburgh, Scranton and Coatesville.

They carry a combined weight of two million pounds, an official said.

The emergency project is expected to cost more than $250,000.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.