Virginia raked in $6.1 million in tolls during the first four months of operation of the 66 Express Lanes, state transportation officials said Thursday.

The new system —with tolls that have reached as high as $47.50 and are among the highest in the nation— is expected to generate $12 million by the end of the fiscal year June 30, the Virginia Department of Transportation said.

The state will allocate nearly half of that amount, $5.7 million, to the Northern Virginia Transportation Commission, which is coordinating transit and other transportation projects along the Interstate 66 corridor.

The rest of the toll revenue “will be spent on expenses related to operations, maintenance and HOV enforcement on the 66 Express Lanes,” VDOT spokeswoman Michelle Holland said.

The NVTC is reviewing 15 projects that could get funding, including more bus service and bike infrastructure.

The peak-direction, rush-hour toll lanes operate on a dynamic pricing system, meaning the toll fluctuates based on demand, traffic and speed.

There were about 13,656 vehicle trips per day eastbound between 5:30 and 9:30 a.m., and 16,447 vehicle trips per day westbound between 3 and 7 p.m., according to VDOT’s latest performance report. Nearly 44 percent of all trips were carpools – which use the lanes free.

The average price for a round trip (a.m. and p.m. averages combined) was $12.65; $8.19 was the average price for eastbound trips and $4.46 was the average price for westbound trips, the state said.

While tolls that topped $47 made headlines, VDOT said only 674 trips — out of 581,672 total– had tolls of $40 or more.

Still on Monday, Transportation Secretary Shannon Valentine said VDOT will adjust the pricing algorithm on system in an effort to lower tolls, answering to demands from lawmakers and commuters who have been stunned by the price to drive the 10-mile stretch from the Capital Beltway to the District line.

The state will be testing various options, including lowering the target travel speed from 55 mph to allow more cars to enter the lanes and possibly bring down toll prices, Valentine said.

Transportation planners have said they hoped the tolls would encourage commuters to use public transportation or carpool during peak travel times. Solo drivers can use the lanes if they are willing to pay; usage is free for vehicles with two or more people and an E-ZPass Flex transponder set to carpool mode.