While cars will soon whiz along Route 23, Balligomingo, closed three weeks ago, is expected to be blocked to all but the locals until next May.
The project was needed to correct sight problems at the intersection, where for years drivers had a difficult and unsafe merge onto Route 23 from Balligomingo.
The new layout moves Balligomingo 400 feet to the west so that it hits Route 23 at a T-shaped angle. There will be a traffic light, rather than the current stop sign, and dedicated turn lanes where none are now.
Last year, Route 23 was blocked off and detoured at Balligomingo as workers relocated utilities and rebuilt a bridge over a creek. A drainage system was added to avert flooding.
In a second phase, the two-lane highway was closed between Matsonford and Swedeland Roads so curbs could be added and the roadbed raised and resurfaced. On Tuesday, workers were installing the last 600 feet of guide rail.
In the final phase, due to end in May, Balligomingo's position is to be shifted on a hillside overlooking the Schuylkill.
"We'll be moving rock and shaping up the slopes," said Sal Ali, a PennDOT assistant construction engineer.
Locals have been allowed car access up to the construction zone, but outsiders have been detoured from West Conshohocken west on I-76 to the Gulph Mills exit, then east on Trinity, Holstein, and Swedeland to rejoin Route 23.
Since early July, with both Route 23 and Balligomingo closed, drivers have sat in traffic jams up to a half-hour on Trinity and Holstein Roads near the I-76 exit. PennDOT knew motorists were annoyed.
"With Balligomingo Road closed right now, that put even more importance on getting Route 23 open," Blaum said. "For this three-week period, it just exacerbated a very difficult situation."
Contact Bonnie L. Cook at 610-313-8232 or bcook@phillynews.com. Read her MontCo Memo blog on philly.com.