Southbound Express lanes are seen next to the outer loop of the Beltway. (Tracy A. Woodward/THE WASHINGTON POST)

This is your code book for cracking the mysteries of the 495 Express Lanes, the biggest new thing in the D.C. region’s transportation system in decades.

They are a little like HOV lanes and a little like Maryland’s Intercounty Connector, but not enough like either for drivers to get by without some prep work. Even familiarity with the Capital Beltway will get them only so far in anticipating the express-lanes experience.

Among the many questions commuters ask as they consider a test drive this coming week, these are the essentials.

What are the 495 Express Lanes? Generically, they are know as high-occupancy toll, or HOT lanes. A private consortium picked up most of the cost to build them in exchange for the right to collect tolls.

Some drivers will pay a variable toll to use them. Motorcyclists will ride free. Drivers who assemble a carpool of three or more also can ride free. Buses ride free, too, creating an incentive for transit services. There’s no exemption for hybrids. These rules will be in effect around the clock and every day of the year.

Where are they? These four new lanes are in the middle of the Beltway between Springfield and just north of the Dulles Toll Road. That’s 14 miles from end to end. There are two lanes in each direction. They are separated from the Beltway’s regular lanes by white bollards set eight feet apart. Only at the ends can drivers slide in and out of the express lanes. The other access points are at interchanges.

What makes them different? The public-private partnership is an unusual way to finance public infrastructure. But for commuters, the essential difference is the tolling system.

The tolls will be used to manage traffic flow and guarantee a reliable trip. When the lanes are lightly used, the tolls will be low. As the lanes get more crowded, the tolls will rise. Some Beltway drivers will see those higher tolls appear on signs near the access points and decide it’s too pricey, so they’ll stick with the regular lanes.

The tolls will keep rising to ensure that the remaining users of the lanes are driving at least 45 mph.

What’s the toll, really? This is the most frequently asked question of all. Dynamic tolling is a new concept for the D.C. region’s drivers. They don’t like paying tolls, and they especially don’t like paying tolls that can change frequently based on sensors feeding traffic-flow data to computers.

The lane operators say they expect the toll at quiet times could be about 20 cents a mile, rising to about $1.25 per mile in some segments during rush hour.

Most drivers won’t go the whole route. They will pay a total for the segments they use. Some segments may be more congested than others. The operators estimate the average cost of a trip at $1 or $2 off-peak and $3 to $6 during rush hours.

Will tolls rise while I’m driving? This isn’t like handing your teenager a cellphone and the next month staring at a $500 phone bill you didn’t see coming. Express lanes drivers will know the maximum toll up front, at the point where they are deciding whether to use the lanes.

The toll rate will be locked in when they pass under the first toll gantry at the start of the trip and won’t rise or fall for them while they are in the lanes.

What signs am I looking for? When approaching access points, look for the purple and white “E-ZPass” sign followed by “EXPRESS” in black letters. Under some of those signs, drivers will see blocks of black type that state the rules on who pays tolls and who doesn’t.

Below the E-ZPass EXPRESS banner on other signs, drivers will see a message board displaying three tolls. The first two will be current tolls to popular destinations. The bottom line will be the toll all the way to the end of the express lanes.

Preparing to leave the lanes, drivers should look for signs that say “E-ZPass EXPRESS EXIT.” There’s almost always an orange and black sign nearby that says “LEFT EXIT.”

Do I need an E-ZPass? Yes, unless you are riding a motorcycle. If you already have an E-ZPass and don’t plan on carpooling, you are all set. If you want to form a three-person carpool for a free ride, get a new type of transponder called an E-ZPass Flex.

The Flex has a switch. In one setting, it’s a regular E-ZPass and allows the electronic readers to assess the toll. The other setting — announced by a beep as you toggle the switch — tells the reader that you are claiming the carpool exemption.

How do I get one? In Virginia, drivers can apply online at They also can apply at one of the state’s E-ZPass Service Centers or call 877-762-7824. Virginia charges a monthly fee of 50 cents for the standard transponder. New customers must prepay $35 in tolls. Starting in January, the Flex fee will be $1 a month. It will be waived for drivers who use it regularly in the carpool setting.

Maryland’s E-ZPass program offers the Flex as well as the regular transponder, but the rules are different. Maryland offers three options for buying the Flex: Go to the Maryland program’s Web site at, call 888-321-6824 or stop by any E-ZPass Maryland Center.

What if I use the lanes without one? Then you didn’t pay your toll. You can go to and click on “Missed Toll?” to pay online. In addition to the toll that was in effect at the time you drove, there will be a $1.50 administrative fee. If you don’t pay online, you will get a letter assessing the toll and adding a fee of $12.50. If a driver ignores toll notices, the information will be turned over to a debt collector.

Enforcement? State police will patrol the lanes. They have spots near toll gantries they can stop and monitor compliance with the toll rules. They receive a signal when a nearby driver is using the E-ZPass Flex to claim the carpool exemption. They can count.