BOSTON - The state Department of Transportation has approved rates for the new gantry system that will replace toll booths along the Massachusetts Turnpike at the end of the month.

The DOT board of directors voted this week to approve rates for 16 gantry locations that are scheduled to go online Oct. 28. According to DOT, board members incorporated public feedback into their process.

The new gantry rates will lead to a $7.1 million decrease in revenue, but that decrease will be absorbed into $20 million in annual savings that will be realized when the Western Turnpike bonds are paid off in January, and will also be offset by the estimated $5 million in annual savings associated with the move to all-electronic tolling, according to the agency.

With the new pricing structure, all vehicles with an E-ZPassMA transponder will receive a discount; vehicles without a transponder will be mailed invoices, and will pay higher rates. For example, under the new rates, motorists with a transponder taking the turnpike from the Route 146 interchange to the Copley/Prudential exit in Boston will save 20 cents. But for motorists traveling without a transponder, that same trip will go from $3.60 to $6.15, according to the toll calculator.

The transponders are available free of charge. Under the gantry pricing, some travel on the turnpike in Springfield and Worcester will be free if drivers enter and exit the road between gantries, the state DOT said. That is the case, for example, for a drive from Auburn to the Route 146 Millbury exit that now costs 25 cents.

For more information on obtaining an E-ZPassMA transponder, go to www.mass.gov/ezpassma. To find out how the new gantry system will impact the cost of your commute, go to the state's online calculator at http://www.massdot.state.ma.us/highway/TollCalculator.aspx.