Traffic jams are a daily frustration for commuters who rely on the Blue Route, the 20-mile expressway that forms part of Interstate 476 in Delaware and Montgomery Counties. The highway links Interstate 95 to the Pennsylvania Turnpike and the Northeast Extension, completing a 132-mile stretch that runs from Chester north to Scranton. 

On a typical day, more than 100,000 vehicles rumble up and down I-476 locally, and during rush hour that traffic slows to a crawl. 

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"It's a peak-hour problem, in our eyes," Timothy Stevenson, a project designer for PennDOT, said recently of that congestion. Traffic is especially bad in Delaware County along a 9-mile stretch where the highway is two lanes in both directions, from West Chester Pike south to the connection with I-95 in Ridley Township. The northern portion of the Blue Route, above West Chester Pike, is three lanes wide on each side of the highway.. 

In the coming years, to ease traffic on the two-lane section of the highway, PennDOT plans to try a new solution. The department will create what officials described as flexible third lanes by widening the shoulders on both sides of the median. Overhead signals will be installed to let drivers know when they can use these lanes, which will usually be during peak travel times. 

The concept is similar to the traffic patterns motorists have experienced while crossing the Delaware River Port Authority's four bridges between New Jersey and Philadelphia.

"If you've driven over the river bridges, you'll see overhead lane control signs with Xs and green arrows telling you when a lane is open for traffic," Stevenson said. "We're going to be doing that same kind of lane control along I-476 so that drivers know when the lane is legally open for use and when it is meant to be used as a shoulder. When it's in use, it will be a flexible travel lane. When it's not, it will be the left shoulder for both directions."

Construction is targeted to begin in 2027 and could be completed in three years if things go smoothly for PennDOT. The project has a budget of about $60 million, making it much cheaper and more achievable than it would be to add new lanes by widening the highway. 

"The money is laid out, and I would say it is reasonable to expect that they stay on that schedule," said Jackie Davis, a long-range planning manager at the Delaware Valley Regional Planning Commission, which evaluates the performance and needs of the area's transportation infrastructure. . 

I-476 is formally named the Mid-County Expressway. It's also called the Veterans Memorial Highway, but the road is best known by its numerical designation or simply as the Blue Route, a moniker whose origin traces back to the 1950s and references the color that highway planners used to show the highway's proposed pathway on their maps. There also were green, red and yellow routes under consideration at the time.

When the Blue Route was mapped out, engineers had to balance community input with the goal of maximizing the highway's capacity. 

"Every transportation project is kind of a negotiated agreement of all the key stakeholders," said Brett Fusco, another planner at DVRPC. "The neighbors in that area, at the time the road was being planned, came to a consensus around two lanes in each direction."

PennDOT estimated that would be enough to handle the volume of cars and trucks anticipated in the years after the Blue Route opened in 1991. But population growth in the Philadelphia region and the rise of multi-car households made the highway prone to traffic jams sooner than expected.

"I think we hit the (projected) traffic volumes for 30 years out almost 10 years after we opened up the roadway," Stevenson said. "The latent demand was just there that the modelers had not necessarily predicted."

PennDOT introduced the idea of building flex lanes in 2017, promising to find workable solutions to the congestion plaguing major highways in the Philadelphia area. In addition to its plans for the Blue Route, the department is in the preliminary design phase for a project to add flex lanes to I-76. A third project is being considered for the U.S. Route 30 bypass between Downingtown and Coatesville in Chester County, and flex lanes eventually could be added to Route 422 in King of Prussia, too.

When the shoulder widening is finished on the Blue Route, overhead signals will let motorists know that they can use the flex lane. A shoulder will always be maintained on the right side of the highway for emergencies and other instances when a driver needs to pull over. During off-peak travel times, the flex lanes will function as left shoulders and traffic will be contained to two lanes. 

"It's not meant to be for full-time use. It's meant to be operated in times of need," Stevenson said.

The volume of vehicles on the Blue Route during rush-hour isn't just a problem for people stuck on the highway. When traffic gets bad, many drivers exit I-476 and clog smaller roads in the surrounding communities. 

"Freeways typically have better safety performance," Stevenson said. "You don't have pedestrian dangers that you would have on local roads and arterials."

PennDOT views flex lanes as a part of the active traffic management strategy it has applied to other highways in the region in recent years. Another element of that strategy are the variable speed limit signs, like those installed on the Schuylkill Expressway in 2021 which the transportation department credits with reducing rear-end collisions. The Blue Route is scheduled to get variable speed limit signs in early 2026. 

Other plans for I-476 include installing more ramp meters, which control the rate of cars entering the highway at interchanges,  preventing bottlenecks and safety hazards.

Michael McGuire, PennDOT's project engineer for the flex lane project, said construction on the Blue Route will be complex. There are a number of median structures and bridges that need to be reconfigured to make the shoulder expansion feasible.

Once operational, flex lanes will be monitored by PennDOT's traffic management control division.

"If we observe on a Saturday morning in August that I-476 is backing up because everybody is going to the shore or they're taking kids back to college, we will have the ability to open that lane up," McGuire said.

They also could be opened when there's a crash in a middle lane or to accommodate traffic for major events and holidays. Also, there will be times when only one side of the highway has its flex lane open. The goal isn't to permanently expand the number of lanes on the highway, which otherwise handles off-peak hours pretty well with two lanes.

"By adding a full-time lane, you might invite more traffic around the clock, but by adjusting to peak travel times, you're kind of trying to maintain a constant state of traffic flow because reliability is one of our core goals for the roadway system," Davis said. 

If planners overcorrect highway traffic in the region with a full-scale expansion, there's the risk incentivizing car travel too much at the expense of other modes of transportation. 

"I think these types of lanes are more East Coast than West Coast (like in) Arizona and California, where they'll build six-, seven-, eight-lane highways," said DVRPC's Chris King, who works in transportation operations management. "We're not promoting that. We would like to promote being more efficient with the resources and facilities that we have now."

In addition to the bridges that cross the Delaware River, PennDOT's flex lanes are inspired by highways in Northern Virginia, which once had reversible lanes on a portion of I-76 that connects to I-495 in Fairfax County. Virginia has since converted some of those roads in congested areas into express lanes that are accessible only to motorists who have E-ZPass, a spokesperson for the Virginia Department of Transportation said. In New Jersey, another example planners cited is U.S. Route 1 in Middlesex County, where flexible shoulder lanes are opened to traffic during peak hours. 

In the foreseeable future, PennDOT's plans for flex lanes will be limited to highways in Southeastern Pennsylvania, Fusco said. Adding them on I-76 is expected to take longer to complete than the Blue Route, planners said, because the Schuylkill Expressway's bridges and other infrastructure cannot accommodate wider shoulders. 

PennDOT hasn't determined how enforcement will be handled on the Blue Route to stop drivers from using the flex lanes when they're closed. One option might be automated camera enforcement. Also some states with flex lanes have installed gates to block traffic in the shoulder lanes when they're not meant to be used, officials said. 

"I think it will be pretty intuitive," King said. "Obviously, there will be an adjustment and a lot of public outreach promoting it when it happens, like with all new strategies. ... This system might be very successful because it's more dynamic. PennDOT is really going to be proactive in operating it. I think it will be a best-case study for others to follow once they get it up and working."