ALLENTOWN, Pa. — A project to widen Interstate 78 in Lehigh County could one day ease congestion and travel tension — but probably not for a decade.
The state Transportation Department is working to finalize its plans for the project, which is set to be completed in phases through 2036.
The first phase will see crews overhaul the I-78 interchange at Adams Road in Upper Macungie Township and replace the bridge that carries the road over the interstate.
The Kecks Road bridge over I-78 in Weisenberg Township also is to be replaced. That work is projected to start in 2030.
The next part of the project calls for an overhaul of the interchange at I-78 and Route 100 in Upper Macungie.
The new layout is set to be a diverging diamond interchange, where vehicles are directed to the “wrong” side of the road so they can turn left onto ramps without crossing in front of oncoming traffic.
It would be the first interchange with that design in the Lehigh Valley.
Additional lanes, easier merging
And in the final phase, crews are to add a third lane in each direction on I-78 along between Route 863 and Route 100, which includes the busiest portion of any road in the Lehigh Valley.
More than 126,000 vehicles traveled Interstate 78/Route 22 between the highways’ merge point and Route 100 in Upper Macungie Township every day last year.
That’s a rise of almost 55% over the previous decade, according to a LehighValleyNews.com analysis of PennDOT traffic volumes.
PennDOT officials say the extra lanes will reduce bottlenecks and crashes by making it easier for vehicles to merge, while adding significant traffic capacity with the region’s population expected to continue growing in coming decades.
Feedback collected through June 5
The population of Lehigh and Northampton counties has grown by more than 21,000 people since 2020, and more than 100,000 more people are expected to live in the region by 2050, according to Lehigh Valley Planning Commission.
That growth is driven by a strong job market and migration patterns, according to regional planners.
Lehigh County ranks within the top 5% of all U.S. counties for international migration, and Northampton County is in the top 5% for domestic migration.
PennDOT officials unveiled plans for the project this month at Fogelsville Elementary School.
That meeting served as the kickoff for a monthlong public-comment period, during which residents can submit questions, concerns and other comments about the project that should wrap up in 2036, according to PennDOT.
Officials are collecting feedback online through June 5.
