NEW BRITAIN – Gov. Dannel P. Malloy and a top federal transit official signed off at an elaborate ceremony today on the last and biggest piece of funding for the New Britain-to-Hartford busway, a symbolic project for a new governor impatient to invest in public infrastructure.

Malloy linked today’s ceremonial signing of a $275 million “full funding grant agreement” at Central Connecticut State University to his administration’s major investments in bioscience, economic development and transportation.

“If you want to bank on failure, do nothing,” Malloy said. “If you want to bring about success, do everything in your power, on as many fronts as you can, all at once, to get your state, your community moving again.”

Malloy said the busway – a $567 million project to which the state will contribute $112 million – is one of the investments Connecticut is making to end two decades of economic stagnation.

“It’s clear to me that the people of Connecticut want action, and they want action now,” Malloy said.

Peter M. Rogoff, the federal transit administrator, said the project will ease congestion on I-84 for commuters from Hartford’s western suburbs, spur smart-growth development along the route and provide a quick stimulus of 4,000 jobs to the state’s depressed construction industry.

With a politically divided Congress unwilling to approve a new jobs program proposed by President Obama, the federal administration was happy to make the signing into a public event attended by Rogoff and several other federal transit employees who had worked on the project.

“President Obama has been insistent that investments in infrastructure are a critical component of the recovery of our economy and a critical component of making sure that everyone’s tax dollars goes to do what our grandparents did for us: and that is invest in our infrastructure, invest in our water and sewer systems, invest in our transportation systems, so that we can have an economy that can grow,” Rogoff said.

Malloy and Rogoff were joined by U.S. Sen. Joseph I. Lieberman and New Britain’s newly elected mayor, Timothy O’Brien, who says he endorsed the project as a city alderman, a state legislator and, now, as mayor.

But opponents say the total cost of $567 million is too high for a 9.4-mile busway linking New Britain to Hartford. State transportation officials project a daily ridership of 16,000, drawing some commuters out of their cars. Some existing commuter buses also will leave I-84 for the busway.

Some opponents say they fear the investment will detract from efforts to eventually extend commuter rail service from Hartford towards Bristol and Waterbury. Others question if there will be a sufficient market for the state’s first rapid-transit service.

At peak times, buses will run every three minutes, stopping at 11 stations between downtown New Britain and Union Station in Hartford.

One protester holding a sign objecting to the cost silently greeted those attending the ceremony. State Sen. Joseph Markley, R-Southington, who is leading a last-ditch effort to kill the project, did not attend, but he called the ceremony a non-event.

“It’s not like they showed up with $400 million,” Markley said, a reference to the approximate federal share of the project. With Congress under intense pressure to reduce the deficit, Markley says the federal funding should not be seen as a sure thing, despite the full-funding agreement.

“I think there’s all sorts of ways for this to fall to the wayside,” he said.

But Rogoff and Lieberman said the signing of the full funding agreement is an important milestone.

“Once the federal government signs an agreement, as we did today, that become a priority for funding in the years ahead,” Lieberman said.

Rogoff said that even deep cuts that could be triggered by the failure of the bipartisan “Super Committee” to agree on a deficit-reduction plan are unlikely to jeopardize the project.

“It could result in perhaps some percentage trims going forward. That could mean we might have to pay our obligation off a bit longer,” Rogoff said.

Unrelated to today’s signing, the federal government today was expected to send Connecticut $45 million in previously promised funds for the busway.

The federal funding for the project is from a variety of federal sources, with the $275 million approved today coming from “New Starts,” a program for rapid transit projects. Obama has sought $3.2 billion for the program in this fisal year, while some congressional Republicans have called for its elimination.

The busway would resemble a trolley or light-rail system, using custom two-piece “articulated” buses instead of trains.

Buses also would run over city streets to the busway from Westfarms mall and the University of Connecticut Health Center in Farmington. Express buses to Hartford from Waterbury and Cheshire would enter the busway in New Britain.

State Transportation Commissioner James Redeker said his conversations with environmental officials leave no doubt that the project will clear the final regulatory hurdle: the granting of an environmental permit.

The state opened bids last week for the first phase of the project. Estimated to cost $35 million, the apparent low bid by Manafort Brothers of Plainville was $26.7 million. Five of the six bids were under $29 million.

The first contract is for the construction of a station in downtown New Britain, the demolition of an old railroad bridge over Route 9, the construction of a new bridge, retaining walls and reconstruction of an off-ramp from Route 72.

Thirteen years in development, it was left to Malloy to make the final decision in April to abandon or go ahead with the busway.

Pushed by construction unions hungry for work and business groups eager for an economic stimulus and better public transportation, Malloy approved the project, whose initial planning was conducted during the administration of Gov. John G. Rowland, now a radio host critical of the busway.

Lieberman noted Rowland’s role during his remarks.

The DOT decided to pursue the busway during the Rowland administration after concluding that other options, such as commuter rail or adding lanes to I-84, would be prohibitively expensive.

Redeker said the busway was the cheapest option to build, operate and maintain.