Every once in a while — and perhaps especially now, if we’re really going to talk about a trillion-dollar infrastructure program — we need to revisit the basics: “This is probably a column-length question, but what are the solutions to traffic congestion in the D.C. region?”

That reasonable question came in during the midst of last Monday’s online discussion about whether traffic conditions would be improved if everyone just went faster. (In fact, we would not all be better off if you’d just go as fast as the driver behind you wants.)

What are we really hoping to achieve when we talk about congestion relief? Based on what travelers have told me over the past decade via letters, emails, blog comments, chat questions and face time, many people define congestion relief as a return to a previous state when their travel times were lower than they are now.

To achieve that, you’re most likely going to have to move or change jobs, so there’s less space between home and work. There’s very little in today’s transportation planning — real or imaginary — suggesting that a decade or two from now the current commute that most people endure will take less time than it does now.

Virginia has the D.C. region’s most aggressive program for infrastructure development. That’s both roads and transit. Yet people working on Virginia projects generally don’t speak about making your commute shorter. They talk about making it less worse than it would have been if their project didn’t get built. They compare their plans with a “no build” scenario, and by comparison, their plans look good because they have smaller areas of red and orange — indicating congestion — than the do-nothing version. But of course, that doesn’t mean the project has solved the congestion problem.

Here’s an example. Virginia’s plan for “congestion mitigation” is part of the Smart Scale scoring system that evaluates planned projects on the likelihood that they will improve “person throughput” and reduce delays. For Northern Virginia and Hampton Roads, congestion mitigation is weighted highest among the factors considered in project scoring, which also include considerations about economic development, accessibility, safety and environmental quality. When big projects in Northern Virginia were scored, the high-occupancy toll lanes project outside the Capital Beltway ranked highest. This project, scheduled to begin construction later this year, will create two HOT lanes and three regular lanes in each direction between the Beltway and Gainesville.

The Virginia Department of Transportation presented the chart below in support of the HOT lanes project. It shows three scenarios involving westbound traffic: average travel speeds during the afternoon rush if nothing is done by 2040, average travel speeds by 2025 if the project goes ahead and average travel speeds by 2040 with the project in place.

Conditions in 2040 look ghastly if nothing is done. With the HOT lanes project complete by 2025, things look much better. But by 2040, that nasty red and orange shading is creeping back in. The situation looks bad compared to 2025, yet it still looks better than the do-nothing chart for 2040.

Planners assume the D.C. region will continue to grow and that travel demand will increase. But they don’t design the infrastructure to create free-flowing traffic at rush hours. That would be inefficient, since the infrastructure would still be there during all those off-peak hours when the travel demand is much less. And the construction cost — already high — would be prohibitive.

This isn’t an argument for doing nothing. But during this national debate over potentially big new infrastructure programs, be wary when the discussion swings to “congestion relief.” Much of what the various advocates are talking about is replacing old roads and bridges that are “decaying” or “crumbling,” as many stories will say. That work is important for safety, but it’s not congestion relief.

These days, congestion relief usually comes in small doses. It might be a new turn lane at an intersection where drivers now get stuck for several light cycles. Or, as in the case of Interstate 66 and some of the other big projects we discuss, it might be temporary relief at the completion of the project that evolves into something more like, “Well, at least it’s better now than it would have been if we did nothing.”