Eastern Pennsylvania’s first diverging diamond intersection will open to motorists Monday morning at Routes 222 and 322 in Ephrata Township.
The $10.9 million project creates a traffic pattern that aims to minimize the ways drivers enter or leave the path of other drivers, referred to as “conflict points.”
Conflict points are the most common sites of car crashes, according to the Pennsylvania Department of Transportation. A prime example is when a car turns left across oncoming traffic and gets T-boned, said Dave Thompson, a spokesman at PennDOT.
“The key safety improvement is you’re removing your conflict point, which is your left turns … because we actually put you on the other side of the road,” PennDOT project manager Dave Fratangeli said when the agency unveiled the plan in 2017.
The double-helix design means the flow of traffic in both directions on Route 322 will briefly switch sides below the Route 222 overpass. For example, a vehicle traveling in the eastbound lane of Route 322 will switch to the westbound lane while traveling under the Route 222 bridge before returning to the eastbound lane.
It might sound disorienting for motorists new to diverging diamonds, but Thompson said drivers should stay alert like they’re driving in an unfamiliar area.
“I suppose there might be a bit of a learning curve for people who are used to using that intersection, and now will come to it and it will be different,” Thompson said. “But there are numerous diverging diamond interchanges all over the country” that many visiting drivers encounter.
The diverging diamond also creates more efficient traffic light cycles, Thompson said. For instance, drivers turning left from one of Route 222’s off-ramps won’t have to wait for a green arrow to turn. Instead, drivers will turn left with traffic without having to get to the right side of the road.
Perhaps unlike any other diverging diamond in the United States, the routes 222 and 322 interchange will include lanes for horse and buggies as well as bicycles, Thompson said.
While the new traffic lanes will open to motorists for the first time Monday, some work remains, Thompson said. Crews will close off one of the interchange’s ramps during off-peak hours at night to finish repaving each of them, add lighting and other work, Thompson said.
That work will likely conclude in the fall, Thompson said, earlier than scheduled.
An average of 19,000 vehicles travel on Route 322 at the Route 222 overpass every day, according to a PennDOT traffic volume map.
The first diverging diamond in the U.S. was built in Missouri in 2009. Pennsylvania’s first diverging diamond is in Washington County near Pittsburgh. It was built in 2016 at the interchange of Interstate 70 and U.S. 19. It was the 73rd diverging diamond in the country at the time, according to PennDOT.
Work continues on another diverging diamond in York County at Interstate 83 and Route 851. That project, with an estimated cost of $30 million requires more work, Thompson said, including the rerouting of a creek.