In addition, as of Jan. 13, the American Public Transportation Association tells us that public transit agencies had identified 787 ready to go public transit projects totaling $15.9 billion that would sustain and create another 440,000 jobs.

Transit projects not only create jobs, but they also support long-term economic growth. People and businesses are attracted to areas with transit connections, and investments in public transit bring increased economic activity. Communities across the nation are reaping the benefits of transit-oriented development - from New Jersey, where a recent report found that the new Hudson-Bergen light-rail line has spurred more than $5 billion in development, to Texas, where the Dallas Area Rapid Transit system has generated more than $4 billion in economic development projects since 1999 and has transformed the urban landscape of Dallas.

The economic recovery bill that President Barack Obama signed on Feb. 17 provides about $47 billion for transportation - including highways, bridges, transit, freight rail, passenger rail and port investments - but our needs are much greater. According to the U.S. Department of Transportation, the backlog of needed improvements to simply maintain the current highway and bridge network alone is $495 billion.

We need a new surface transportation authorization bill to begin to bridge that gap and to establish a sustainable long-term source of funding for transportation investments.

The current transportation authorization bill, SAFETEA-LU, expires on Sept. 30, and it remains our goal to complete a new authorization this year. My committee has begun the authorization process with hearings in Washington, D.C., and in California in the past year. We have heard from mayors and county supervisors, state departments of transportation, air quality experts, business and labor leaders and other stakeholders. We will continue to make sure all points of view are considered.

I have worked with the bipartisan leadership of the Environment and Public Works Committee to develop a set of principles for the next bill, which will be titled "MAP 21" (Moving Ahead for Progress in the 21st Century). These principles include improving safety, facilitating the efficient movement of people and goods, and reducing congestion and its impacts.

I am particularly interested in addressing traffic congestion, which slows down the movement of people and goods and contributes to poor air quality and global warming pollution.

According to the California Air Resources Board, approximately 75 percent of diesel particulate emissions in California are related to goods movement. Freight transportation is still largely driven by fossil fuel combustion. With that combustion comes emission of greenhouse gases, carbon dioxide, nitrous oxide and particulate matter.

In addition, CARB has attributed thousands of premature deaths to diesel emissions and estimates that the cumulative health costs of diesel emissions are tens of billions of dollars.

We need to find ways to reduce congestion and alleviate transportation bottlenecks even as our population continues to grow, placing new and greater demands on existing transportation systems. Transit will be a vital part of the solution. According to the most recent Texas Transportation Institute report on congestion, public transportation saved travelers 541 million hours in travel time and 340 million gallons of fuel in 2005.

Funding is another critical issue that must be addressed. The latest estimates from the Federal Highway Administration show that the Highway Trust Fund is continuing to take in less than is being spent. If this trend continues, we may need to infuse the trust fund with additional cash before the end of 2009.

The tragic bridge collapse in Minneapolis in 2007 demonstrated the need to increase investment in infrastructure, not decrease it. World-class roads, bridges and transit systems are crucial ingredients for a world-class economy. That will take money, and the discussion of funding options will be a key element of the next bill.

We are looking closely at sustainable funding sources. The gas tax is not a long-term solution, so we need to explore new alternatives. We have heard many ideas, including user fees, fees based on vehicle miles traveled, freight fees and infrastructure bonds.

The next surface transportation bill provides an opportunity to take a fresh look at how we move people and goods, address air quality and global warming, and make the changes necessary to ensure our transportation system helps support short-term recovery and long-term prosperity for America.

Sen. Barbara Boxer is chairman of the Senate Environment and Public Works Committee.