United States Department of Transportation - Federal Highway Administration FHWA Home Feedback
   Home   divider  end of menu

Photo: Bridge with clouds

Geotechnical Home
space image
Geotechnical Solutions/Best Practices
space image
Geotechnical Training
space image
Geotechnical Newsletters & Publications
space image
Geotechnical Calendar
space image
Geotechnical Links
space image

FHWA Resource Center

Geotechnical Team

Federal Lands Publications

Technology Development Reports on Geotechnical issues by Central Federal Lands:

Magazine Articles

Deep Foundations

Grouting Tips: An Outlook on Post-grouted Drilled Shafts

Benjamin S. Rivers, PE
Geotechnical Engineer
FHWA Resource Center

FHWA Publications

Geotechnical Software

SNAP-2 (Soil Nail Analysis Program)

News Articles

Trade Publications/Press Coverage

FHWA Announces Excellence in Highway Design awards Up front News and Views on 2005 competition. (December 2004)

Army of Steel Pipes Support Tough Pennsylvania Highway (2/14/05) By Jonathan Barnes
Courtesy of ENR Magazine

Mile by mile and pin by pin, contractors are stabilizing and widening a Pennsylvania highway once studded with crosses marking the sites of traffic fatalities.

The notoriously dangerous two-lane, 7-mile stretch of Lewistown Narrows highway is now undergoing a $105-million retrofit and widening to four lanes. It is the state's most complex highway project ever, says Gary Hoffman, PennDOT deputy secretary for highway administration.

Walsh Construction, Chicago, won the four-year contract to reconstruct the length of Route 22/322 in 2004. Hemmed in on the north side by boulder-strewn slopes and on the south side by the Juniata River and the Pennsylvania Canal, crews also must allow two lanes to remain open for 20,000 vehicles a day to pass.

The road will be reconfigured so that the eastbound, riverside lanes are separated from and lower than the westbound lanes. Concrete barriers will separate the sets of lanes. "We're putting in fill at the base of the slopes that will act as a counterweight [against the slopes of the mountain], and the westbound lanes will be on that fill," Hoffman says.

Pilings drilled into the bedrock pin the roadway in place. The technique is rare in Pennsylvania and has never been used to such a great extent in the nation, says Neil Fannin, a PennDOT geotechnical engineer. "The amount of pilings we're using there is exceptional."

The 7-in.-dia steel pipe pilings range in length from 15 to 45 ft. The pilings are drilled through a top layer of soil, then through a clay layer and embedded 6 ft into the bedrock. The "micropiles" are filled with grout, which will bond the pipes to the rock. Each pipe has a 0.5-in. wall thickness and are spaced 1 to 2 ft apart for three miles, says Jonathan Raab, geotechnical engineer with Harrisburg-based GTS Technologies Inc., development and design consultant. "Without a doubt, the Narrows is the largest project with these types of stability issues that has ever been done in the state."

The Federal Highway Administration did not have a strong precedent for the design of the project, Raab notes. "This method of micro-pile stabilization has been used elsewhere, but on a much smaller scale," he says.

With the scale and the variety of soils, "the application here is unique because of the geology of the site and the difficulty of what we're trying to do," FHWA geotechnical engineer Silas Nichols says.

More information about Engineering News-Record, the international newsmagazine covering the construction industry

Press Releases

Trade Publication Index
Disclaimer: The United States Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear herein only because they are considered essential to the objective of this site, to share the most pertinent information available.


To view PDF files, you can use the Adobe® Reader®.

FHWA Resource Center logo
yellow circle
staff / phones

Technical Service Teams
Air Quality

Civil Rights

Construction & Project Mgmt


Finance Services




Pavement & Materials


Safety & Design



FHWA Home | Feedback
United States Department of Transportation · Federal Highway Administration