In the coming decades, current forecasts indicate the growth in trips taken on the region's roadways will outpace increases in lane miles of roadway. This will lead to increases in congestion system-wide.
The following maps show the expected changes in morning peak-hour highway congestion between 2015 and 2040 based on improvements included in the CLRP as well as population and employment changes.
Severe stop-and-go congestion is expected to be prevalent throughout the entire region in 2040, not just in isolated areas. However, the HOT projects included in the 2014 CLRP are projected to relieve some of the congestion along major highways in the region.
Overall, congested lane miles are a relatively small proportion of the total lane miles in the region both today and in 2040. However, the total number of congested lane miles is forecast to go up in all 3 sub-areas with the greatest expected increase in the inner suburbs. The share of lane miles that are congested is also expected to increase in all sub-areas, but the highest rate of increase is expected in the outer suburbs.
Though a relatively small share of lane miles are currently congested, a higher share of Vehicle Miles Traveled (VMT) is currently on congested roadways. This indicates that the roadways that are congested are some of the more heavily traveled in the region. In 2040, VMT on congested roadways is expected to increase in each sub-area as well as the share of VMT on congested roadways.
Due to a lack of funding for capacity enhancement projects to accommodate all of the projected transit ridership growth in the region, the Metrorail system will likely reach capacity on trips to and through the regional core. According to a WMATA study (shown below), without additional railcars beyond those currently funded, four out of five lines entering the core will become congested or highly congested by 2040, and the Orange/Dulles, Yellow and Green lines are forecast to be highly congested.