BOSTON (CBS) – In exchange for giving a lift to other passengers on the Mass Turnpike, the state’s transportation department provides valuable cash discounts.

But records the WBZ I-Team obtained raise questions about whether anyone is actually keeping an eye on the honor system to make sure it’s not abused.

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And those questions are already prompting MassDOT leaders to take a closer look at the program when the new all-electronic tolling (AET) system rolls out at the end of the month.

On Monday, the I-Team discovered AET could mean big changes down the Pike with possible concepts like “congestion pricing.” It appears the transition could also affect the carpool transponder program.

On the Expressway, drivers save time using the HOV lane. State troopers can often be seen looking for drivers trying to skirt the system.

On the Pike, commuters save money if they promise to travel with at least three people in the car. After paying an upfront fee of about $100, tolls are free for the rest of the year.

A daily commuter driving to Boston from a western suburb like Marlboro can save about $400 per year in tolls.

However, in the past two years, none of the 2,500 carpool drivers ever received a fine for misuse of the program, according to records the I-Team obtained.

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Since 2011, not one person has been removed from the program for failing to have the required number of passengers in the car.

“We have to have a program that is common sense and enforceable,” MassDOT Highway Administrator Thomas Tinlin told the I-Team when asked about those figures.

It’s unclear how many drivers could be cheating the system on the Pike. But back in 2014, the I-Team followed several lawmakers who were routinely commuting to the Statehouse using their carpool transponders without the required number of passengers.

The elected leaders later refunded hundreds of dollars back to taxpayers.

Because of the WBZ questions, Tinlin said he has asked for a full briefing about the program from the statewide tolling director.

“I think it’s a healthy time to reexamine the programs that we offer,” he said. “Were we making sure that people were using it the way they should have been using it? And if not, does it make sense to continue?”

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Ryan Kath can be reached at rkath@cbs.com. You can follow him on Twitter or connect on Facebook.