The end of the month.

That's when construction will resume on two of the Pittsburgh area's busiest highways:the Parkway East/Interstate 376 and Interstate 79 west of the city.

Parkway East improvements that started Downtown in 2006 and advanced east of Oakland last year will shift farther east this year, covering three miles from the Edgewood-Swissvale Exit to Business Route 22 in Churchill.

The Pennsylvania Department of Transportation decided to delay work until March 29-30, one week after Easter. Weather permitting, one inbound lane will be closed on that and succeeding weekends, when traffic volumes are lighter, in order to start replacing deteriorated concrete slabs.

From midnight to 5 a.m. beginning today and continuing until Friday morning, lanes will be closed periodically for 15 minutes while engineers step out onto the highway to measure bridge expansion dams, which also will be replaced as part of the $22.3 million project.

"It takes about 16 weeks to fabricate new expansion dams," PennDOT spokesman Jim Struzzi said. "Taking field measurements now will enable us to jump-start the manufacturing process."

An exact date hasn't been set, but also before the end of March, "prep work" will get under way for the second year of the two-year, $61 million reconstruction of I-79 between the Ohio River and the I-279 junction in Franklin Park.

This season, traffic will be maintained on the new northbound lanes while the southbound lanes are reconstructed. The same type of traffic patterns will be in place, including establishing a weekday "local lane" for drivers to enter or exit at the Mount Nebo Road interchange.

Partly because the work zone is in the least busy stretch of I-79 through Allegheny County, the traffic control strategy was successful last year. There were no serious backups, even though the average daily traffic volume of 42,000 swells significantly on Friday and Sunday during the summer vacation season.

West Mifflin-based Trumbull Corp. and New Castle-based Lindy Paving Co., who have partnered for numerous road-building projects in the region, hold both the Parkway East and I-79 contracts. The latter has an asphalt plant on Neville Island near I-79 and one along Second Avenue, Pittsburgh, with easy access to the Parkway East.

PennDOT is planning to hold what it calls a "kickoff news conference" in several weeks to provide more information for motorists.

Mr. Struzzi said although some weekend closures are planned in one direction at a time on the Parkway East, they'll be shorter and less disruptive than last year, when drivers were sent on detours that took them through Wilkinsburg and Squirrel Hill.

"Once again, we're scheduling all the work we possibly can for weeknights and weekends," he said, except for the busiest weekends, such as the Fourth of July, when all work will be suspended. "We're working to provide the least possible inconvenience for our customers."