Senate Environment and Public Works Committee Chairman Barbara Boxer (D-Calif) and other committee leaders have reached agreement on an outline for the highway-policy portion of a hoped-for new surface-transportation measure.

A key element of the framework, which Boxer and her colleagues announced April 10 at a press conference, is to set highway funding at current levels plus a increase to account for annual inflation.

Boxer said that would require a $16-billion-a-year increase over present revenue amounts that flow into the Highway Trust Fund. Boxer said the lawmakers want a long-term measure, which could be as long as six years.

There is nearly universal agreement that the key question underlying the envisioned new bill is where to find that $16 billion a year. That task will be up to the tax-writing committees, Senate Finance and House Ways and Means.

The lawmakers who signed on to the agreement are Environment and Public Works' “Big Four” on highway issues. Besides Boxer, they are David Vitter (R-La.), the committee’s top Republican; Thomas Carper D-Del.), transportation and infrastructure subcommittee chairman; and John Barrasso (Wyo.), that subcommittee’s leading GOP member.

Vitter told reporters that he and the other senators expect to have the bill ready for committee action after they return from the two-week Easter-Passover break, which ends on April 28.

The "EPW" panel’s highway-policy measure would be only one piece of a final surface-transportation package, which would succeed the 2012 Moving Ahead for Progress in the 21st Century Act, or MAP-21.

The banking committee would have to add a transit title, the commerce committee is responsible for highway-safety issues and, most importantly, Finance would have to provide a revenue title. Vitter said Finance “has to lead all of us in helping to figure out how to pay for this [multi-year bill].”

Vitter also said the goal is to have the Senate act on the package by July or August, when the trust fund's highway account is projected to fall into a deficit position. Another deadline is Sept. 30, when MAP-21 expires.

In the House, Transportation and Infrastructure Committee Chairman Bill Shuster (R-Pa.) has said he hopes to have his panel vote on a highway and transit policy bill in spring or summer.

Boxer said other principles in the Big Four's outline include provisions to “expand opportunities" for rural regions; continue to “leverage local resources to accelerate the construction of transportation projects”; and require “better information-sharing regarding federal grants.”

Vitter said the expanded role for states would be reflected  “in a number of important areas that give localities and states more flexibility.”

U.S. Transportation Secretary Anthony Foxx has said the Obama administration also plans to propose a surface-transportation bill soon.