I-80 Job on Track, Despite Undercutting

Tue June 13, 2006
Jennifer Rupp

The 7-mi. (11.3 km) refurbishment of I-80 between Yarnell and Bellefonte in Pennsylvania is running on schedule, despite extensive undercutting because of clay and other fine materials.

The project began on Feb. 28, 2005, with the westbound lanes and is expected to wrap up by Nov. 22, 2006, with the completion of the eastbound lanes.

“This section of I-80 was built in mid- to late-60s. The original embankment fills were constructed mostly of rock until the last few feet to subgrade. It appears they capped their fills off with a varying depth layer of clay and other fine material,” said David Karp, Pennsylvania Department of Transportation (PennDOT) project manager.

“This is typical but can create problems. During initial construction, crews found that rock and other course embankment materials couldn’t be fine graded to within the specified subgrade tolerance so clay and other fine materials were used when available.

“I believe the open, unsealed joints and cracked slabs allowed water, salt, etc. to penetrate/saturate the subgrade [which was clay in fill areas]. This water eventually froze causing accelerated deterioration to the concrete pavement slabs,” Karp continued.

“We also use loaded tri-axle trucks to identify areas that may not appear visually unstable but will pump/move under the weight of the equipment. This method was specified in the original contract. The designer estimated approximately 30 percent of the entire subgrade east and westbound may need undercut for stabilization prior to constructing the planned pavement structure. The same labor and equipment is used to remove the undercut material that is used during the excavation to subgrade.”

Karp explained the details of the undercutting.

“We undercut below the planned subgrade anywhere from one to 24 inches where soft, unstable subgrade conditions existed, mainly in fill areas capped with clay.

“Class 4, Type C, reinforced geotextile is placed at the bottom of the undercut prior to placing rock backfill to add further stability. We’re also placing Class 4, Type A, geotextile on non-undercut subgrade areas prior to sub-base placement as an additional subgrade stabilization measure.

“Every effort is made to ensure that the subsurface water has a way to escape so there were many rock outlets placed to drain undercuts. Base drain with perforated plastic pipe is used in non-undercut areas to drain subgrade as per plan, which is standard construction,” concluded Karp.

The prime contractor on the two-year, $43.3-million project is Glen O. Hawbaker of State College, PA. Hawbaker is in charge of the excavation, paving, bridge removal and replacement.

The 7-mi. stretch consists of two lanes each for eastbound and westbound between mile markers 152 and 159, with 10-ft. (3 m) shoulders on the right sides and 4-ft. (1.2 m) shoulders on the median sides.

There are three twin bridges being demolished and rebuilt. Hawbaker is working on a five-span bridge crossing over SR 150/220 and a single-span bridge over SR 1006 (Old Route 220). Nestlerode Contracting Company of Lock Haven, PA, has been subcontracted for the reconstruction of the three-span bridges over Bald Eagle Creek and the steel beam pile driving on all six bridges on the project.

“The major concern for this project is time — basically this is a two-and-a-half-year job, which has to be completed in two years,” said Jeff Laninger, project manager of Glen O. Hawbaker. “The westbound and eastbound bridges over SR 150 were on the critical path both years of the project. The earthwork and bituminous paving have a little more float this year than last.”

“As more undercut and subsequent backfill of the roadway undercuts are encountered, the longer the earthwork takes, which in turn delays the bituminous paving. This is why [along with the cost to the Department] that undercuts are not desirable, but so far we are maintaining the schedule by working two shifts on the excavation.”

Hawbaker is using a variety of equipment on the job, including a Caterpillar 345, a Caterpillar D6N dozer, two Caterpillar 740 articulated trucks, three Volvo A40D articulated trucks, and a Caterpillar 963 track loader, all for excavation.

For the roadway subbase, Hawbaker is using a Caterpillar D8 dozer with stone box, a Caterpillar 12G grader and a Caterpillar CS563C roller. The structural work is being done with a Caterpillar 330BL excavator and a P&H 670TC 70-ton (63.5 t) crane.

Bruce & Merrilees Electric Company of New Castle, PA, is implementing highway lighting, fiber optic conduits and an anti-icing system for the bridges. The $1-million anti-icing system includes weather stations, cameras, and three dynamic message boards. The message boards will have the capacity to assist with homeland security issues and to announce Amber Alerts to motorists.

Green Acres Contracting of Scottdale, PA, is the subcontractor replacing the guide rails, and Protection Services of Harrisburg, PA, is in charge of traffic control.

The project will vastly improve the road conditions and safety for motorists traveling on this section of I-80. The current ADT, including trucks, is 9,396 eastbound and 12,179 westbound.

“We had 97,000 cubic yards of ’borrow’ material that was taken from the median areas within the project limits to construct crossovers for various phases of traffic control. The borrow material was required in the first year because we didn’t start westbound pavement removal until the traffic was switched,” said Karp.

Crews will use a total of 9,336 cu. yds. (7,138 cu m) of concrete to construct the two one-span, two three-span and two five-span structures. For paving, they’ll use 277,066 tons (251,350 t) of bituminous base course, 37,968 tons (34,444 t) of bituminous binder course and 36,495 tons (33,108 t) of wearing, which includes scratch and leveling courses for a total of 351,529 tons (318,902 t).

Laninger said that Hawbaker is running approximately one week ahead of schedule.

“We’ve stayed ahead of schedule for a few reasons. Running a second shift on excavation has helped, the weather has been cooperative, but most of all we’re able to be efficient because of our organized and hard-working crews.” CEG

This story also appears on Construction Equipment Guide.