Adding more than a million people to the region and its transportation system is a potentially very disruptive prospect. Roadway congestion and transit crowding are already challenges for many travelers, and maintenance backlogs for both systems mean conditions could get worse. But the region’s latest Constrained Long-Range Transportation Plan (CLRP) envisions nearly $244 billion in new and ongoing investments in the transportation network over the next 24 years. Much of it will go to operations and maintenance—repaving roads, clearing snow, rebuilding aging bridges, paying train and bus operators and mechanics, replacing aging transit vehicles, and much more. But about $42 billion is expected to go to actual capacity expansions—new or widened roadways, new express toll lanes, new transit lines, or increased service on existing lines.

So how well will those investments handle the influx of population and jobs that regional analysts expect between now and 2040? The TPB recently sought to answer that question in its latest Performance Analysis of the CLRP. The analysis found that congestion and crowding are likely to get worse compared to today, but at somewhat slower rates than if no new projects were built. It also found that investments in more or better alternatives to driving alone will lead to more people taking advantage of other travel options like ridesharing, transit, bicycling, and walking. 

These findings are meant to help decision-makers and the public better understand the anticipated benefits and possible shortcomings of the plan as they review it and submit comments ahead of a November 12 deadline. The TPB is scheduled to vote on an annual amendment to the CLRP on November 16 that would add five major new projects, including new express lanes on I-395 and a VRE commuter rail extension in Northern Virginia, and new bus-only lanes on 16th Street in the District of Columbia.

RELATED: Trains, buses, new lanes for cars and bikes—highlights from the 2016 CLRP Amendment

More lane-miles and new driving options, but still more congestion 

Of the $42 billion in new or expanded transportation facilities planned in the CLRP through 2040, about two-thirds is slated to go to expanding roadway capacity. In all, nearly 1,200 new lane-miles are planned, which would grow the region’s road network by about 7%. The remaining share will add 76 miles of new high-capacity transit lines, growing the region’s transit network by 26%. 
Of the new lane-miles of freeway or expressway that are planned, nearly half will be express toll lanes, like those currently on I-495 and I-95 in Northern Virginia. Express toll lanes aim to give drivers new options, particularly for avoiding congestion, and to incentivize carpooling, vanpooling, and transit use. Tolls in the lanes fluctuate based on traffic levels in order to maintain free-flowing, congestion-free travel. Vehicles with at least three occupants travel in the lanes for free while those with fewer than three occupants pay the variable toll. The CLRP already includes new express toll lanes planned for I-66 inside and outside the Capital Beltway. This year’s CLRP amendment includes new such lanes on I-395. 

Despite these capacity expansions and new options, congestion is still expected to grow considerably by 2040. The number of lane-miles that are congested in the peak hour is forecast to increase by 66%, the average delay per vehicle-trip is forecast to jump 47%, and the total number of daily vehicle-hours of delay may grow by 74%.  These regional averages seem to paint a dark picture of the future, but the CLRP does include some relief for drivers looking for speedier trips. Certain segments of the highway system are expected to see reductions in congestion thanks to planned widening and the addition of new travel lanes. These locations include short segments of I-66 and VA-267 in Virginia, and I-70 near Frederick in Maryland. Many more segments, however, are expected to see traffic conditions worsen over the next quarter-century.

More people ridesharing, taking transit, bicycling, and walking—but driving remains dominant 

The latest CLRP Performance Analysis shows a clear though relatively small shift in travel behavior—away from driving alone and toward alternatives like carpooling, vanpooling, transit, bicycling, and walking. According to the analysis, growth in the number of trips by all other modes is expected to outpace growth in trips by single-occupancy vehicles (SOVs). Among all daily trips, SOV growth comes in at 14%, while carpooling and vanpooling will grow by 21%, transit trips will grow by 32%, and bicycling and walking will grow by 47%. Similar trends show up in the analysis for commute trips to and from work, with each of the key non-driving options expected to grow by 30% or more.

These trends send an important signal that travel behavior in the region is changing. Maybe that’s thanks to planned transit expansions, like the second phase of the Silver Line to Loudoun County, the VRE extension to Haymarket, the Purple Line in Maryland, or the DC streetcar to Georgetown. Or maybe it’s that more and more people are choosing to live and work in dense, mixed-use Activity Centers, often near high-capacity transit options. (Through 2040, 60% of all new population growth and 75% of all new job growth is forecast to occur in these areas!) Or maybe it’s that increased roadway congestion will push people to find other alternatives that are faster, cheaper, or less stressful—or some combination of all three.

No matter the cause, these trends are good news for a region looking to expand travel options and reduce reliance on driving. But the recent analysis also reveals just how dominant driving still is and is forecast to be in the coming years. Nearly 4 in 10 daily trips and 6 in 10 commute trips in 2040 will still be made by single-drivers, which amounts to 8.2 million daily trips, and 2.6 million daily commute trips. By comparison, only about 264,000 daily commute trips are forecast to be made on foot or by bicycle.

What else is in the Performance Analysis and what happens next?

The latest Performance Analysis includes much more data and analysis on how the CLRP is expected to perform through 2040, including on measures of job accessibility, transit accessibility and connectivity, geographic differences in mode choice, and motor vehicle emissions of both regulated pollutants and greenhouse gases. It also evaluates how well the CLRP supports or advances key regional priorities spelled out in the Regional Transportation Priorities Plan.

The public comment period on the draft 2016 CLRP Amendment runs through November 12. The TPB is expected to vote on the amendment at its November 16 meeting. The next update of the CLRP will come in 2018 when transportation agencies will revise their estimates of future revenues and make changes to the plan based on the new financial constraints.

MORE: Get more data and analysis from the 2016 CLRP Performance Analysis 

MORE: Review the draft 2016 CLRP Amendment now and submit your comments