Virginia Gov. Terry McAuliffe came to the King Street rail station Friday morning to describe the details of the Atlantic Gateway program, which he called “the most comprehensive transportation package in Virginia history.” It brings together a grand total of $1.4 billion in road and rail projects capped off this week by a federal grant of $165 million that completed the financial plan.

Among those applauding the governor’s list of what’s ahead for Northern Virginia commuters was Doug Allen, chief executive of Virginia Railway Express. Allen said he’s looking forward to several improvements in the next few years that will give the two-line commuter service more flexibility: construction of about six miles of a fourth main-line track from the south side of the Potomac River, by the Long Bridge, to Alexandria, and the construction of a third track along about eight miles of the main line between the Franconia-Springfield VRE station and the Occoquan River.

The biggest planned improvement for rail commuters — and one only partially covered by the Atlantic Gateway financing — is the rebuilding of the Long Bridge. “Long Bridge is the key” to unlocking the rail corridor, Allen said. The Atlantic Gateway program adds to the tracks on the south side of the bridge and finances engineering work that will eventually lead to rebuilding the bridge and uncorking the bottleneck for freight, commuter and long-distance passenger rail service south of the District.

You can see from the state’s timeline below that the components of Atlantic Gateway already have some history of planning, which no doubt was one of the attractions in Virginia’s grant application to the U.S. Department of Transportation. The commonwealth wound up with 20 percent of the money available nationwide through this FASTLANE grant program.

Among the highway components, the northbound extension of the 95 Express Lanes for about eight miles north on Interstate 395 has been in the works for a while, and the plan to convert today’s High Occupancy Vehicle lanes into high-occupancy toll lanes is well-established.

It’s the program on the south side of the 95 Express Lanes that’s newer and still needs to be refined by the planners. Many Virginia commuters and long-distance travelers know about the notorious bottleneck at the southern terminus, where the express lanes and the regular lanes merge near Garrisonville Road in Stafford County. The state had already planned to extend the express lanes two miles farther south to ease the congestion.

The new plan under Atlantic Gateway calls for extending the lanes 10 miles south to Fredericksburg. There still are important design issues that need to be worked out between the Virginia Department of Transportation and its private partner, Transurban.

All the parties want to ease that bottleneck, but they need to work out whether it still makes sense to create a new entrance/exit for the express lanes two miles away from today’s terminus.

Another issue is whether the 10-mile extension should consist of reversible lanes, in conformity with the rest of the 95 Express Lanes system. Transurban has been working to reduce the amount of time it takes to reverse the direction of the traffic flow to better accommodate the demand. A 10-mile extension of reversible lanes increases the challenge for the staff that does the lane reversal. Perhaps it would be better for everyone if the extension consisted of lanes that are permanently northbound or southbound.

There’s no question that Atlantic Gateway is a big deal. In fact, it’s the biggest single program to ease travel congestion in the Mid-Atlantic region. But travelers in the D.C. region will want to continue watching the evolution of the Long Bridge plan at the northern end of the Atlantic Gateway program and the 95 Express Lanes extension at the south end.

Here’s the timeline that the Virginia state government included in its Atlantic Gateway application for the federal grant.