Drivers could get confused when the 95 Express Lanes project converts High Occupancy Vehicle lanes on Interstate 95 into High Occupancy Toll lanes. The project will link the new HOT lanes with the old HOV lanes on Interstate 395 north of the Beltway. (Tracy A. Woodward/The WASHINGTON POST)

As drivers prepare for the opening of the 95 Express Lanes this month, many of their questions come down to this: What’s HOT and what’s not?

The project is going to convert today’s High Occupancy Vehicle (HOV) lanes on Interstate 95 into High Occupancy Toll (HOT) lanes, and it’s going to link those new HOT lanes with the old HOV lanes on Interstate 395 just north of the Beltway.

Among the many concerns drivers have about this HOT/HOV combo pack, none surpasses what they envision happening in the transition zone north of the Beltway near Edsall Road. The letter below focuses on a key aspect of that widespread concern.

Dear Dr. Gridlock:

Assuming the 95 Express Lanes are a huge success, exactly what does the Virginia Department of Transportation plan to do to alleviate the obvious problem of the very large number of non-carpool vehicles exiting the express lanes onto the I-395 regular lanes near Edsall Road between 6 and 9 a.m.?

It would appear that they have done little but create a catastrophic traffic problem at a place already jammed far, far beyond the road’s capacity.

James Hill, Springfield

DG: I share Hill’s concern about the transition zone. Officials with VDOT and with Transurban, the company that operates the express lanes, have said since this project began that they also are focused on the traffic flow and safety issues in this area.

My immediate concern about the zone is a bit different from his. I worry that some drivers will hit the brakes and make sudden lane shifts as they reach the points where they would need to move from one set of lanes to another.

This is the problem scenario in the northbound HOT lanes: Toll-paying drivers — people who do not have at least three people aboard and can’t claim the free ride offered to carpoolers in the HOT lanes — need to exit the HOT lanes during peak periods before they become the HOV lanes.

If they don’t take that last exit on the right side, they could get a ticket for violating the HOV3 rules during rush hours. (Off-peak, this isn’t a problem.)

I’ve seen video simulations showing how many warning signs a driver will pass when approaching the HOT lanes terminus. To me, the signs appear impossible to miss. But I know from the opening of the Beltway HOT lanes two years ago that drivers will miss signs.

The potential problem southbound involves drivers who are in the HOV lanes just before they become the HOT lanes.

This might be you if you’re a carpooler, but you still don’t have an E-ZPass Flex transponder to claim your free ride in the HOT lanes. You don’t want to enter the toll lanes and get charged the toll plus an administrative fee, because the operators had to send a bill to you.

Or it might be you if you leave your job in the District after the HOV3 rules expire at 6 p.m. At that hour, you can drive solo in the HOV lanes, but you may want to get out of them before you reach the new tolled zone.

It certainly would be better to slide past that last exit than to slam the brakes in the middle of an interstate highway, but that doesn’t mean it won’t happen.

So I ask drivers to avoid getting distracted while they are in the HOT lanes. Regular commuters probably will get used to the new alignment quickly, and making the proper lane changes will be a matter of muscle memory.

But not always. And then there will be the drivers — including those who live in Maryland and the District — who use the HOV/HOT system only occasionally. They’re not going to memorize these rules, and may find themselves realizing an error only at the last moment.

In expressing this concern, I don’t mean to diminish the other issue about the transition raised by Hill. The northbound merge from the HOT lanes to the regular lanes of I-395 may well prove problematic.

To ease that, VDOT is building an auxiliary lane on the right side of northbound I-395 between Duke Street and Seminary Road. The auxiliary lane — not quite done yet — is meant to ease traffic in the merge area and make it easier for drivers heading for the Mark Center at Seminary Road.

The first few weeks after the HOT lanes open probably will be difficult for merging traffic, because it’s new. Traffic engineers are unlikely to make anything more than small adjustments before things settle down a bit.

Here’s one thing to watch for after those first few weeks: Is there more traffic on the interstate, or is it just distributed differently?

The HOT lanes project adds a lane to the former HOV section on I-95. But the commuters that I-95 drivers see around them will probably be the same set they see today. People don’t react that quickly to a change in the transportation system. They won’t immediately start commuting on I-95 because the HOT lanes opened.

If the HOT lanes do ease up travel for everybody on I-95, they could become an incentive for people to find new jobs or housing along that route.

But those new drivers won’t be the immediate concern. The immediate concern will be whether the same old drivers we have today pay attention to their new environment.