PORTLAND — A national transportation research organization has identified 50 transportation-related projects that it says would support economic growth in Maine and improve residents’ quality of life.

The projects encompass the entire state, from replacing the Martins Point Bridge in Portland and rehabilitating the Sarah Mildred Long Bridge in Kittery to developing a new cargo port at Sears Island and building an east-west highway from Calais to Coburn Gore.

Most of the projects listed by TRIP, a nonprofit organization based in Washington, D.C., would cost millions of dollars. The east-west highway would cost an estimated $1 billion to build.

Some of the projects already have been funded.

Frank Moretti, director of policy and research for TRIP, said he was going to present the organization’s findings during a press conference Thursday at AAA headquarters on Marginal Way in Portland.

TRIP, founded in 1971, is sponsored by insurance companies, equipment manufacturers and labor unions that advocate maintaining a safe and efficient transportation system nationwide.

“In the long term these improvements will enhance economic competitiveness and improve the quality of life for the state’s residents and visitors by reducing travel delays and transportation costs, improving access and mobility, improving safety and stimulating sustained job growth,” TRIP says in the introduction to the report it will present today.

The Maine Department of Transportation has no obligation to implement any of TRIP’s recommendations, but the list carries some clout, said Pat Moody, spokesman for AAA.

He said that, hopefully, the report will refocus public attention on Maine’s deteriorating transportation infrastructure and bring pressure on state legislators and the governor.

“The important thing is that we keep this issue in the public spotlight,” Moody said. “There are so many competing interests, transportation funding could get lost in the shuffle.”

State Rep. Ann Peoples, a Democrat from Westbrook who serves on the Legislature’s Transportation Committee, compares the state’s transportation system to a stately Victorian home.

A visitor who approaches is struck initially by the well-kept grounds and exterior, she said. The first floor is beautiful, but a visitor who goes deeper into the home will find dust and battered furniture on the second floor, and leaks in the roof.

Peoples said the Maine Turnpike and Interstate 295 are the approach to the Victorian home; it’s the secondary roads and bridges that need repairs.

Peoples said it may be time for the state to issue a transportation bond, but Gov. Paul LePage, at least in 2011, has opposed such a bond.

Republican Sen. Ron Collins of Wells, who co-chairs the Transportation Committee, said the administration has indicated to him that the governor might be willing to reconsider his position on bonding in 2012.

“I think the governor will be more receptive to a bond next year than he was this year,” Collins said.

In the meantime, Collins said, there is an “abundance of shovel-ready (construction) projects” in Maine.

One of the top priorities identified by TRIP is replacing the Memorial Bridge between Kittery and Portsmouth, N.H.

New Hampshire’s Executive Council announced Wednesday that it has approved an $81.4 million contract with the design-build team of Archer Western Contractors of Chicago and HNTB Corp. of Westbrook.

Demolition of the old bridge, which was closed to traffic earlier this year, is set to begin in January. The new bridge is expected to open by July 2013.

Under an agreement between New Hampshire and Maine, New Hampshire will be the lead agency on the project while Maine will take the lead role for the proposed rehabilitation of the Sarah Mildred Long Bridge.

TRIP identified that bridge among its top 10 transportation projects. Maine recently awarded a $6 million design contract to HNTB for the bridge’s rehabilitation.

In response to the report, Ted Talbot, spokesman for the Department of Transportation, said, “We certainly appreciate (TRIP) calling attention to important projects, but their top priorities may not coincide with ours.”