Interstate 79 slices through western Pennsylvania, carrying motorists from the West Virginia border through Pittsburgh and northward to Erie and the Great Lakes.
PennDOT photo
The interstate is approximately 200 mi. long and faces serious congestion issues as it intersects Route 910 in Wexford. Interstate 279 is only a few miles away, and with the Pennsylvania Turnpike also in the area, congestion issues can compound quickly.
PennDOT planners determined that a new interchange project at Route 910 would disentangle back-ups and help prepare the busy area for coming decades. PennDOT is working with Golden Triangle Construction and a team of subcontractors to create a full offset single point urban interchange that will eliminate traffic lights and enable drivers to reach their destinations more efficiently.
The project carries a price tag of $46.5 million with work continuing through the 2027 construction season. The project is now 50 percent complete.
Nick Warner and Steve Sneddon are supervising the project for PennDOT.
“The Route 910 corridor is very busy with many businesses in the area and two traffic signals close together,” Warner told Construction Equipment Guide. “This causes traffic backups on I-79. By building a single-point urban interchange, we can eliminate some traffic signals and relieve the wait time. The existing traffic signals in the area are saturated.”
Because of the tight spaces in the project footprint, PennDOT decided to build two flyovers — both for northbound traffic. Workers also will widen Route 910 and reinforce the outside shoulders of I-79.
“That area has limited real estate to acquire and work with,” said Warner. “There is a farm there, which is an important community asset. So, we wanted to work quickly and efficiently on this major interchange used by motorists going to and from Pittsburgh.”
The two flyovers are steel multi-girder structures. The bridge piers will stand on caissons that are 36 in. in diameter, and drilled approximately 30 ft. deep, including partially into rock using a hydraulic drilling machine. The abutments are supported by steel piles, which were driven with a pile hammer held by a crane. By July, the construction team had set all the new girders over the interstate. The next step is the preparation for the deck placement, including rebar. The workers will soon be placing concrete for the new bridge decks.
PennDOT photo
Workers will be using polyester polymer concrete (PPC) on the flyovers. The coating cures quickly and is highly resistant to salt and moisture.
“This material is very strong and should give a longer life for the bridge,” said Warner. “The existing bridge that carries traffic over I-79 is in decent shape. Our team will give the old bridge new bearings and an overlay with PPC.”
The construction team also will be building new piers and abutments. Safety, of course, is paramount and most of the work will be done behind barriers, offering maximum protection for the workers and motorists. When the project winds down, the construction team will perform some milling and overlay for I-79 near the new flyovers.
“The schedule is aggressive, but we are hoping to open the ramps this year,” said Warner. “As always, weather will be a factor and could delay the opening.”
Workers will be using approximately 6,000 cu. yds. of concrete, 5,000 tons of asphalt and 3.5 million lbs. of steel. The team needed to excavate approximately 150,000 cu. yds. of material in preparation for the flyovers. The team also will provide new highway lighting, new pavement marking and guide rail updates.
The new road will be 12 in. thick on top of a substantial subbase.
PennDOT photo
Golden Triangle and the subs will be using mostly standard equipment, including excavators, dozers, articulated trucks, wheel loaders, skid steers and pavers. Many pieces of equipment will be equipped with GPS, enabling equipment operators to be precise in the grading and placement of material.
When the road work is done, the construction team will build a stormwater management system. The system will include building two new retention ponds and precision testing for the soil. Workers need to ensure that the soil will hold water temporarily, then allow it to slowly seep into the groundwater below.
Sneddon quoted PennDOT statistics for the value of the project.
“It is estimated that this project will save roughly $8 million in part because of fuel savings for motorists not having to idle in traffic, and less congestion in the area. There will be substantial improvement in the general flow of traffic and efficiency of the signals. When there is increased efficiency and less traffic congestion, improved safety is a natural byproduct.”
