Port-aggedon is right around the corner.

Truckers and others who regularly drive from Long Beach over the Gerald Desmond Bridge to cargo-rich shipyards at the ports of Los Angeles and Long Beach might want to make a few dry runs around the traffic-jammed ports complex before Saturday’s closure of a key ramp.

Truck drivers might not be alone in feeling effects of the work as they jostle for open roads and find alternate routes to reach the ports.

Traffic could be affected on I-710, I-110, the 91, the 47/103 and some nearby surface streets, such as Anaheim Street and Pacific Coast Highway, trucking company executives say.

It’s all part of the next step in building a $1.263 billion, twin-spired replacement for the Gerald Desmond.

“The traffic going into and out of Terminal Island is going to be a zoo,” said Michael Johnson, trucking operations manager for Long Beach-based Port Logistics Group. “There won’t be a 710 freeway to Gerald Desmond anymore because it’ll be cut off, gone.”

Starting at 10 a.m. Saturday, orange cones will be placed near the southern end of I-710, pushing traffic onto Pico Avenue.

Truck drivers and others will be forced to take a detour over Pico that has been restriped with more lanes, with some dedicated for trucks to flow directly into the Matson terminal on Pier C Street.

Less than a mile south of the I-710 off-ramp, drivers will get funneled back onto the westbound Ocean Boulevard lane over the Gerald Desmond. That is the port’s main detour route to deal with the 1,200 vehicles per hour that drive over the ramp during peak times, though other routes are being suggested to help relieve traffic tie-ups.

Still, truck drivers are getting headaches just thinking about long lines, along with the addition of a traffic light at Pico and Pier D Street to help control traffic flow back onto the bridge.

“There’s not much we can do about this,” said Robert Curry Sr., president of California Cartage Co. LLC, in Long Beach. “We don’t like it.”

Curry said most of the few hundred truckers who haul containers daily from waterfront terminals to his main warehouse off the 103 and Pacific Coast Highway may try alternative routes if the Pico detour has crushing backups.

“Most will go over Pico, and if they see it is congested, they’ll use PCH or (West Anaheim Street),” he said. “The bulk of them use telephones and radios and communicate to dispatchers. They do many trips a day. They won’t go Pico anymore if they run into traffic.”

The port is publicizing alternatives to the Pico detour to help give truckers and other drivers as many options as possible.

Electronic message boards and other detour signs will be posted along I-710 to alert drivers of these routes.

Tow trucks will be parked on standby along I-710 and elsewhere to deal with accidents or breakdowns, with California Highway Patrol in the area to remind motorists to slow down.

Alternatives to Pico will include taking the westbound exits off I-710 at Anaheim and driving south along the 47/103, or taking the PCH exit off I-710 and picking up the 47/103.

These routes all end up at terminals along the waterfront to the west of the Gerald Desmond.

Some truckers say the alternative routes could cause even more traffic congestion on the 103 – especially at the Schuyler F. Heim/Henry Ford Bridge – where a bottleneck forms with construction taking place on yet another replacement bridge.

A four-lane bridge is being built to replace the Schuyler F. Heim, a vertical lift bridge that opened in 1948 and is one of three that connects with Terminal Island. The old Schuyler F. Heim has been narrowed down to one lane in each direction while construction is underway.

The other two bridges that connect with Terminal Island are the Gerald Desmond and the Vincent Thomas Bridge, which has connected the Port of L.A.’s San Pedro waterfront for more than half a century.

“We’ve got to figure this out. Maybe we’ll get some directions on how to get around,” said Julio Arrazola, a Long Beach truck driver who was washing his cab on Friday along Anaheim Street. “Imagine 50,000 trucks trying to get to the harbor when the bridge is gone. It’s going to be a crazy day.”

Another route that could result in heavier traffic is the 91 to the southbound I-110.

Because of the ramp closure, Johnson predicts a huge volume of trucks going this way to major Terminal Island container yards run by APL, APM, Evergreen and Hanjin in the Port of L.A.

“It’s going to be a lot heavier, not just a little heavier,” said Johnson, who also wears the hat of president of the Harbor Trucking Association, which represents intermodal carriers in the area. “I anticipate there’ll be a lot of confusion initially on where everyone will go.”

A few days after the ramp’s closure, excavators and powerful jackhammers will begin knocking down the 1,200-foot-long connector, said Steve MacLennan, program director for the Gerald Desmond Bridge replacement project.

For the railroads, the ramp demolition through June 20 means that cargo movement in and out of the Port of Long Beach’s eastern piers will temporarily stop over Memorial Day weekend, according to John Pope, a spokesman for the port.

Thick steel plates, mounds of dirt and huge wood beams will be used to protect the tracks when the ramp’s spans are taken down overhead.

Harbor Scenic Drive also will be briefly covered at some point to protect it.

“As soon as the old ramp is out, we’ll immediately begin building the foundation structures and pilings for the new bridge,” said MacLennan, a contractor hired by the Port of Long Beach from Parsons Brinckerhoff to oversee the work.

Once the ramp is gone, Shimmick/FCC/Impregilo, the contractors building the new supersized Gerald Desmond replacement to the north, will begin installing pilings twice as deep as the old bridge and columns twice as tall.

Port planners say the Pico detour will be the main route for 30 months until contractors can complete the Gerald Desmond replacement by mid-2016.

“It’s going to make a difference in our lives,” said Elvin Aviles, an 18-year trucking veteran who hauls container loads for Dependable Highway Express in the ports complex. “It’s going to be really hard to get around.”

Contact the writer: 562-243-5497 or pmaio@lbregister.com