The Senate Commerce Committee unveiled a bipartisan bill Thursday to provide $78 billion in funding for rail networks, major grant programs and road safety agencies, a second jigsaw piece in efforts to put together a transportation spending package.

The five-year bill would provide $25 billion for passenger rail, most of it in the form of grants to Amtrak, boosting the federal government’s support for intercity train travel. The bill also proposes $28 billion for transportation construction grants, including a new program worth $2 billion a year to fund the largest projects.

“With the economy rebounding, it’s imperative that our long-delayed transportation needs are addressed,” said Sen. Maria Cantwell (D-Wash.), the committee chair. “Whether it’s moving people safely, delivering freight on time or addressing environmental needs, this legislation is a down payment to thrive and compete in the innovation economy.”

Cantwell worked on the bill with the committee’s top Republican, Sen. Roger Wicker of Mississippi. He said the bill was in the committee’s tradition of bipartisanship and would “grow the economy by increasing authorized funding and making improvements to our rail, freight, ports, research and safety programs.”

The committee is scheduled to consider the bill at a meeting Wednesday.

The bill was introduced the same day a committee in the House advanced — largely along party lines — a $547 billion transportation spending package that includes $95 billion for rail. The full House is expected to vote on that legislation the week of June 28.

In the Senate, several committees share responsibility for drafting an equivalent bill. The new rail and safety legislation would be stitched together with a $304 billion highway funding proposal the Environment and Public Works Committee adopted late last month.

It then would need to be joined with a transit funding measure being negotiated by leaders of the Banking, Housing and Urban Affairs Committee. Finding an agreement might prove tricky: At a recent hearing, Sen. Patrick J. Toomey of Pennsylvania, the committee’s top Republican, questioned the need for more federal transit spending after bus and rail agencies received $70 billion in pandemic relief. Aides from both parties said discussions continue.

Congress renews the transportation programs about every five years and faces a Sept. 30 deadline to pass a bill before the current legislation expires.

Lawmakers are working on the bill parallel to a White House effort to assemble a broader infrastructure package that President Biden initially outlined at $2.3 trillion.

But in each case the legislative proposals have adopted some of the president’s ideas. For example, the Commerce Committee bill would create a new office, called the Advanced Research Projects Agency-Infrastructure (ARPA-I), that the White House plan also seeks.

The bill provides money for grants that are highly sought by states and local governments to tackle projects they might not otherwise be able to afford. It includes $1.5 billion a year for the flagship program the Biden administration calls RAISE (Rebuilding American Infrastructure with Sustainability and Equity) and a further $1.2 billion a year for the INFRA (Infrastructure for Rebuilding America) freight-focused program.

The new $2 billion a year fund would target the biggest projects, including those expected to cost more than $500 million.

Another program in the bill would provide $800 million annually to remove or redesign culverts to aid the passage of salmon and other migratory fish and back projects that reduce the harm runoff causes to fish and shellfish.

The bill also funds the federal car and truck safety agencies, calling for new technology such as automatic emergency braking and driver assistance features to improve safety. It would provide $200 million annually to back Vision Zero initiatives, which help local officials plan for how to reduce road deaths.