BOSTON — The 68-year-old Tobin Bridge is set for a major facelift, and North Shore motorists can expect delays over the next two years.

Work gets underway on a $41.6 million renovation of the 2-mile-long truss bridge over the Mystic River on April 22. The project focuses on a 1,675-foot stretch of the bridge into Chelsea.

It will mean lane and ramp closures well into 2020, according to the state Department of Transportation.

That’s likely to create headaches for tens of thousands of commuters who cross the bridge each day.

MassDOT officials are urging motorists to plan ahead, as one lane on the lower deck, Route 1 northbound, will be closed through November 2018.

“We encourage people throughout the Greater Boston area to recognize the upcoming traffic impacts on the Tobin Bridge and make smart choices if they will be traveling along the Route 1 corridor or throughout the region,” state Highway Administrator Jonathan Gulliver said in a statement.

There will also be lane closures during off-peak times on the upper deck, Route 1 southbound, according to MassDOT.

The work includes repairing steel on the upper and lower decks, and concrete on the lower deck. The project also involves waterproofing, resurfacing and new pavement markings.

Workers will also upgrade utility lines, install new curbs, and build a new parking lot under the bridge between Williams Street and Third Street.

The bridge’s on and off ramps will be upgraded. The Everett Avenue on-ramp will be closed for about a month starting in late April. After that, the Beacon Street off-ramp will close for about two months.

Closure of the Fourth Street off-ramp is expected in November, according to MassDOT.

Transportation officials say motorists can use the website mass511.com, or the GoTime travel app to check for delays and find alternative routes.

Just the beginning?

Mary Connaughton, director of government transparency at the Pioneer Institute, a Boston think tank, said the project will mean unavoidable disruptions.

“There has never been a better time for drivers from north of Boston to consider a commuter rail pass,” she said.

Connaughton, a former Massachusetts Turnpike board member, said the state’s transportation infrastructure is showing it age, and other disruptive projects are likely on the horizon.

“Many of the major roadways and bridges constructed in the 1950s and 1960s are in poor shape, and there is no end to the large-scale repair projects to be performed throughout eastern Massachusetts in the foreseeable future,” she said.

In 2012, the Tobin underwent $35 million in upgrades that included deleading and repainting the bridge as part of a preservation project. Two years ago, MassDOT removed the toll booths on the bridge and switched to electronic tolling.

Transportation advocates say the state’s infrastructure is at a crossroads and requires major investment, and new approaches, to reduce congestion.

“Traffic is holding back our economy, creating pollution and hurting quality of life,” said Chris Dempsey, director of the advocacy group Transportation 4 Massachusetts. “And the congestion on the Tobin Bridge is bad, even on a good day.”

The group is urging MassDOT to consider “Smarter Tolling” on the Tobin, where prices are lowered during off-peak times and raised during rush hour.

“Think of it like an early bird special at a diner. You get a discount for going at a certain time,” he said. “It’s an approach that other places in the U.S. have been using for years, and has led to improvements in traffic congestion.”

Transportation 4 Massachusetts has paid for billboards along Route 1 that highlight quality time commuters may be missing while idling in traffic jams.

“Traffic is stealing your time and money,” reads one billboard ad. “That’s highway robbery.”

Christian M. Wade covers the Massachusetts Statehouse for The Salem News and its sister newspapers and websites. Email him at cwade@cnhi.com.

TOBIN BRIDGE: QUICK FACTS

Opened to traffic Feb. 27, 1950, as the Mystic River Bridge.

Renamed in 1967 for Maurice J. Tobin, a Boston mayor and governor, who also served as President Harry Truman’s secretary of labor.

Toll was 15 cents when the bridge opened; it’s now $3 for southbound traffic, without an E-ZPass transponder.

It cost about $27 million to build, using about 45,000 tons of steel.

Source: Massachusetts Department of Transportation