The 95 Express Lanes in Northern Virginia aren’t scheduled to open till the start of 2015, but the company that will operate them is planning to launch an education and marketing campaign early this year.

The high-occupancy toll lanes already open on the Capital Beltway showed some of the complexities inherent in this style of driving. Commuters who had little experience with any form of toll road had to learn what it was like to use a toll road with no tollbooths, on which the toll could vary by a few dollars, depending on when they chose to use it.

Though the Beltway express lanes have been open more than a year, drivers still ask me very basic questions about the decisions they need to make and the tolls they have to pay.

The version of the express lanes coming to Interstate 95 follows the same basic concept, but a driver who has been using the Beltway lanes will notice some important differences.

The Beltway system has two lanes in each direction. The 95 Express Lanes, which will stretch 29 miles from Garrisonville Road in Stafford County to just north of the Beltway, will be reversible, with a timing system on north-south lane direction like the one in use today on the I-95 high-occupancy vehicle lanes.

North of where the express lanes will end, the I-395 HOV lanes will continue north to the District just as they do today. But this will make things interesting on the northbound side of the highway during the morning rush.

Drivers who meet the carpool rules for free use of the express lanes will be fine. They can continue in the I-395 HOV lanes. But drivers who are alone or have no more than one passenger will need to exit at the transition point and get back into the regular travel lanes of I-395.

Will this create a new morning choke point as drivers switch lanes? And will it create a new enforcement problem for Virginia State Police trying to catch HOV cheaters on I-395?

The new express lanes also will have the capacity to vary the speed limit, something that isn’t done on the 495 Express Lanes. This is a safety feature unrelated to the variable-toll system used to maintain a steady flow of traffic. The speed limit could be lowered in the face of traffic emergencies or extreme congestion.

Well-traveled drivers from this region may have seen the somewhat similar system employed on the New Jersey Turnpike. The Virginia Department of Transportation experimented with this feature briefly when construction at the Beltway’s Telegraph Road interchange created a choke point for traffic.

Drivers who use today’s HOV lanes on I-95 will experience a big change: a requirement that they obtain an E-ZPass Flex transponder, the type developed for use on the 495 Express Lanes by drivers claiming the carpoolers’ exemption from the tolls.

A similar shock awaits drivers who are used to traveling in the HOV lanes at off-peak hours, when they are open to everyone. That free ride will end. They also will need to get E-ZPass transponders and pay tolls if they don’t have three people aboard.

Drivers who have traveled the Beltway express lanes will notice a major difference in the travel pattern from the I-95 version. On the Beltway, they can slide in and out of the express lanes only at the beginning and the end. All the other connections are at interchanges. On I-95, they will have multiple chances to move between the express lanes and the regular lanes.

And drivers who think they have mastered the nuances of variable tolling on the Beltway will have one more lesson to learn on the I-95 system. On the Beltway, they lock in their toll rate when they enter the express lanes. It won’t change for the duration of the trip.

On the I-95 lanes, they’ll see a price for a certain segment, then if they want to go beyond that segment, they’ll need to watch for signs telling them what the price will be. That’s more things to think about at the start or the end of the workday, when most commuters just want to be alone with their thoughts.

Can drivers handle all that? The financial success of the express lanes depends on it. So beginning this spring, Transurban, the toll lanes operator, will start getting its messages out in a bid to retain the HOV lane users of today and draw in new users with the promise of a reliable trip.

For drivers, it isn’t just a matter of affording the toll. It’s also about understanding the system.

Ask Metro

Metro General Manager Richard Sarles is scheduled to be my guest during the weekly online discussion of local transportation issues at noon Monday. You can submit questions and comments in advance to this Web page: .

We hope to discuss Metro’s proposed fare and fee increases, the rebuilding program and the long-term plan for improved service known as Metro 2025.

Dr. Gridlock also appears Thursday in Local Living. Comments and questions are welcome and may be used in a column, along with the writer’s name and home community. Write Dr. Gridlock at The Washington Post, 1150 15th St. NW, Washington, D.C. 20071, or e-mail .