The Massachusetts House and Senate have endorsed a compromise version of a transportation reform package that would give the state’s transportation secretary sweeping new powers to consolidate the state’s highway infrastructure. It now heads to Gov. Mitt Romney for approval.

The plan would make the secretary of transportation also the chairman of the Massachusetts Turnpike Authority, an independent authority that currently operates outside state government. According to the Boston Herald, the secretary would also become a board member of the Massachusetts Port Authority and chairman of the Massachusetts Aeronautics Commission.

The change would not take place until 2007.

Lawmakers decided to delay the switch to avoid any disruption during the final stages of the Big Dig, which the Turnpike Authority oversees.

Despite the concentration of power in the hands of the transportation secretary, the bill maintains the turnpike as a separate independent authority.

The proposal would require the turnpike to study a sliding scale toll system that would raise and lower tolls to help reduce congestion and operating costs, the newspaper reported. An “Office of Transportation Planning” would also be created to develop a comprehensive plan to improve and maintain roads, passenger rails, freight rail, aviation, shipping and water transportation.

A plan was removed from the final version of the bill that called for placing the turnpike in charge of maintaining and plowing three state-run highways – Interstates 395, 84 and 291.