NEW YORK (CBSNewYork/AP) — State officials say workers have reopened four of five lanes after a fire caused structural damage to a ramp leading to the Holland Tunnel in Jersey City, but ongoing repair work may create gridlock conditions during peak commute hours.

According to arson investigators, the fire started last week in wooden pallets, mattresses and garbage debris and spread to a parked Port Authority police vehicle then to the bridge.

Before sunrise Monday, there was only one lane open on the outbound Holland Tunnel ramp to the NJ Turnpike, Route 139 and Kennedy Boulevard. Drivers WCBS 880’s Sean Adams spoke with were preparing for the worst.

“I’m helpless without my GPS. So I hope my GPS gets smarter,” one woman said.

However, crews were able to reopen four of lanes — it seems they can open and close them as they work, Adams reported. So the backups weren’t as bad as predicted.

Other drivers told CBS2’s Reena Roy that mornings are tough as it is, and the added traffic wasn’t helping.

“This is terrible. I’m pretty frustrated right now,” one woman said.

Some traveling westbound on the New Jersey side said it was more backed up than usual and feared it could be worse during the evening commute, as people make their way home from work through the Holland Tunnel.

“I had no idea what the reason was, but it’s taking about 20 minutes longer that it usually does,” driver Jesse Lamar said.

The Port Authority is urging drivers to avoid the Holland Tunnel during the Monday evening and Tuesday morning commute hours and instead consider mass transit. New Jersey Transit has added capacity to some bus routes and the Hudson-Bergen Light Rail. PATH trains also were added.

Officials specifically warned riders of the 120 and 64J bus routes to expect significant delays during main commute hours.

“Journal Square trains are running at three minute headways and Hoboken’s running at a six minute headway,” PATH General Manager Mike Marino said.

However, Marino worries that overcrowding on trains may start Tuesday if drivers are stuck on the roads Monday night. Either way, they’re prepared.

“We have trains available if we need to, if there’s a rush,” he added.

As Roy reported, it’s all because a fire under the ramp damaged the support beams below the structure. Black smoke could be seen billowing through the air, and the flames burned a police SUV.

CBS2 has been demanding answers from the New Jersey DOT, Jersey City police and fire officials about what was burning under the roadway and how it ignited. They say they are investigating whether a homeless encampment there played a role in the fire.

State transportation department and contractor crews have been working around the clock to place support bracing under ramp, but officials say complete repairs could much longer.

Officials say it’s too early to predict how long permanent repairs will take.

“It is safe to say we are talking weeks, probably months, to fully repair the damage from this fire,” said Andrew Tunnuard of the New Jersey Department of Transportation.

That could mean months of congestion.

“I have to think about that — figure out which way to take home now, because this is really bad,” a woman said.

“I’m going to take the BQE to the Verrazano (Bridge),” said commuter Corey Jackson. “This doesn’t make sense, two hours to get through the tunnel?”

More than 2,600 vehicles per hour and 46,000 vehicles daily travel from Manhattan to New Jersey using the tunnel on average, according to the Port Authority.

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)

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