If all goes according to plan, the new 95 Express Lanes will make it more difficult for motorists expecting to leave their cars parked in traffic on I-95. The 29-mile stretch of High Occupancy Toll (HOT) lanes — from Garrisonville Road in Stafford County to around Edsall Road on I-395 in Fairfax County — should beef up the carrying capacity of current HOV lanes.

Testing began last week on the updated lanes and will continue through the fall, with an anticipated finish date around the end of 2014. Funding for the $1 billion project comes from Virginia’s Public-Private Transportation Act.

The public-private partners for this project are VDOT, the Virginia Department of Rail and Public Transportation, the Federal Highway Administration and Transurban, with 95 Express Lanes LLC joining to help execute it.

“The 95 Express Lanes will use technology to deliver new transportation options and keep drivers moving on I-95 in Northern Virginia,” Kevin Ginnerty, Transurban’s director of project delivery, said in a statement. “Testing the tolling and traffic management system is an important step in the delivery of the 95 Express Lanes and providing a faster trip to customers.”

Cars marked with large white “Test Vehicle” badges on the side doors will test road sensors that provide traffic data used for setting toll prices, overhead radio E-ZPass readers and cameras that automatically detect traffic accidents and then alert the Express Lanes Operations Center.

Toll prices will fluctuate based on traffic demands, encouraging better flow of traffic.

During the testing these cars will be part of regular traffic on I-95 HOV lanes. Part of the testing will also involve breaking in new entry and exit points for the Express Lanes — but only during off-peak hours and on nights and weekends when the HOV lanes are closed.

All drivers will be required to have an E-ZPass to use the new lanes, and carpoolers specifically must have the E-ZPass Flex.