Spikes in traffic congestion during Metro’s first four SafeTrack maintenance surges. (Transportation Planning Board)

It’s a very unlucky driver who has experienced all four of the Metro maintenance disruptions, so for the rest of us, the staff at the regional Transportation Planning Board has done the work.

The planning board released an analysis Tuesday that looks back on the weekday traffic patterns since early June, and that history should not only remind commuters what they’ve been through, but also help them plan for the remaining projects, which continue into early 2017.

The projects stretched across a month and a half and targeted different sections of Metrorail track. So the effects on traffic in the corridor varied. But one important note is that the next project, Surge 5, returns to the same area as Surge 1, so that deserves immediate attention from drivers. These were the four track work zones:

Surge 1: Single-tracking between East Falls Church and Ballston.
Surge 2: Line shutdown between Eastern Market and Minnesota Avenue, or Eastern Market and Benning Road.
Surge 3: Line shutdown between Reagan National Airport and Braddock Road.
Surge 4: Line shutdown between Reagan National Airport and Pentagon City.

The researchers used travel time and speed data reported by Inrix, the traffic information service, to analyze the traffic conditions during the SafeTrack surges. The data covered about 5,500 miles of roadway, including 720 miles of highway and 4,780 miles of other important commuter routes.

The comparisons made in the report are with traffic congestion and travel times for the same periods in 2015, as well as from surge to surge. The researchers have some warnings about that. They note that year-to-year or day-to-day traffic conditions can differ for reasons that have nothing to do with SafeTrack, such as the weather or traffic crashes. But the comparison with the time periods from a year ago should help control for seasonal variations.

These are among the highlights cited by the researchers:

In general, weekday peak-period traffic congestion increased during the first four surges compared with the same time periods in 2015. But Surge 1 saw the most significant increases in congestion. The rush hours during Surge 1 intensified and spread out during the morning and the afternoon.

During the second surge, the morning peak period showed a 5 percent increase in congestion, but there was no significant change during the afternoon peak. However, there was a 7 percent increase in congestion between 2 and 4 p.m.

Surge 3 had the lowest increase in congestion. It was only 3 to 5 percent worse between 6 and 8 a.m. From 5 p.m. and later in the evening rush, congestion was lower than for the same period in 2015.

The series of images shows the impact of the first four SafeTrack surges on travel times. The Metro work zones are circled. (Transportation Planning Board)

During Surge 4, congestion during the morning peak (7 to 9 a.m.) increased 6 percent and increased 5 to 7 percent during the evening peak (between 5 and 8 p.m.).

The congestion increases on the freeways were worse than on the arterials.

As summer begins and the schools close, people go on vacation or at least get more flexible about their travel time, so a seasonal effect shows up in the traffic congestion data. “This may have helped to partially offset traffic increases that may have been introduced by Safety Surges 2 through 4,” the researchers say in their report.

This should give commuters along the Red Line hope for the two surges that affect their travel corridors in August.

This chart isolates the impact of Surge 1 on traffic congestion at the height of the morning rush. (Transportation Planning Board)

The researchers also looked at the locations for the traffic disruptions. See how their results match up with your experience.

For commuters during the morning peak:

During Surge 1, they say, the greatest increases in congestion occurred in the triangle formed by eastbound Interstate 66 inside the Capital Beltway, the George Washington Parkway and the Capital Beltway at Route 267.

For Surge 2, the zones of dismay were inbound lanes toward the District on northbound I-295, the Baltimore-Washington Parkway and D.C. 295 (the part of 295 in the District north of the 11th Street Bridge), westbound Route 50 and the westbound side of East Capitol Street.

During Surge 3, congestion increases occurred along northbound I-395 and Route 1 in Northern Virginia.

For Surge 4, the pain was along northbound I-395, Route 1 and the George Washington Parkway. They doubled their average travel times.

For commuters during the afternoon peak:

During Surges 1 through 3, congestion increases often occurred in areas away from the SafeTrack work zones, rather than closer to them, as was the case with the morning congestion.

During Surge 4, increases occurred around the work zone on routes that included southbound Route 1, the southbound George Washington Parkway, southbound I-395 and nearby portions of the Beltway.

Drivers in the District saw the biggest congestion increases during the height of the afternoon rush during all four surges.