HARRISBURG — Pennsylvania is making a new push to get federal approval for tolls on Interstate 80.

The Pennsylvania Turnpike Commission and state highway department submitted supplemental materials late Thursday to the Federal Highway Administration designed to answer questions about the financial structure of a proposal that has generated spirited opposition in the northern part of the state, including in the Butler County area.

The agencies provided a consultant's analysis that the value of the transaction would be in line with recent highway leases elsewhere in North America. The proposal calls for PennDOT to lease the roadway to the turnpike, which would operate the tolls.

It also provides more information about the money needed to maintain Pennsylvania's interstates, current conditions on I-80 and details about the nine proposed toll collection spots.

I-80 tolls are a key component of a 2007 state law designed to generate billions of dollars to fix roads and bridges and subsidize mass transit systems. That law, which also authorized higher tolls along the existing turnpike system, has already provided more than $2 billion in new transportation money, but revenues will drop sharply in July without the I-80 tolls.

According to the Turnpike Commission, the 2007 law will generate $83 billion over 50 years with the I-80 tolls, but $24 billion without them.

About a year ago, the Federal Highway Administration put the brakes on the I-80 tolling plan, saying it was "unable to move the application forward."