By Evan Gurley
Images provided by T-BO Photography, courtesy of Ayers Associates (ayersassociates.com)
Do you traverse a rough highway on your way home from work? If your answer is yes, it’s not surprising. According to the U.S. Federal Highway Administration (FHWA), there are more than 4 million miles of roads in the United States, and of the nearly 1 million miles of major highways eligible for federal aid, 187,365 miles – or 18.8% – are in poor or mediocre condition and need repair.
Urban highways carry more traffic, of course, and thus get more wear and tear, and almost one-third of all arterial and collector miles are in poor or mediocre condition. The U.S. Department of Transportation’s 2010 “Report to Congress on the Conditions and Performance of the Nation’s Highways, Bridges and Transit,” the most recent report, stated that all levels of government should be investing $123 billion in highway improvements just to maintain current physical and performance conditions on the nation’s highways and bridges.
A better way
As the data above suggest, state DOTs and agencies are faced with many challenges when delivering transportation improvement projects. As a result, DOTs, engineers and public agencies seek more innovative construction practices, emerging technologies and new products to deliver transportation projects. There is a critical need to complete highway pavement repair and rehabilitation projects quickly, with minimal disruption to the users and local communities, and to result in pavements that are long-lasting. The effective use of jointed precast concrete pavement (JPrCP) technology for rapid repair, rehabilitation and reconstruction of pavements addresses this goal. JPrCP falls under the umbrella of precast concrete pavement (PCP) technology.
Because JPrCP technology is relatively new (but growing rapidly), many highway agencies and industry partners have not fully embraced it. However, recent positive field testing results have been documented that should provide confidence for public agencies in the use of PCP technology to achieve rapid repair and rehabilitation.
Highways for LIFE
Another directive funded by the FHWA is the Highways for LIFE (HfL) program. The purpose of HfL is to advance Longer-lasting highway infrastructure using Innovations to accomplish the Fast construction of Efficient and safe highways and bridges. And it is innovation that is the key to finding our way out of the highway maintenance challenge.
The three goals of HfL are to:
- Improve safety during and after construction
- Reduce congestion caused by construction
- Improve the quality of the highway infrastructure
The HfL program has hosted numerous project showcases across the country highlighting JPrCP technology. These showcases have been instrumental in educating local DOTs, contractors and public agencies about JPrCP technology, not only through interaction but having the attendees physically see an installation at the project site. The following are two such projects documented with comments about the project and the advantages of using precast concrete:
SR 11/Broad St. Pavement Rehabilitation – Winder, Ga.
About the project:
- The work was to be fast-tracked to minimize the number of construction days involving lane closures. It was estimated that JPrCP panels would save the contractor one to two months of construction time and keep user delays to a minimum.
- The high percentage of regular and truck traffic coupled with parking has led to varying levels of cracking and rutting both under and above the old pavement.
- The average rutting, measured at four intersections, ranged from approx. 5/8 in. to 1-1/2 in. The underlying base material also varied in thickness. This resulted in cracks and various forms of pavement distresses.
The precast advantage:
- The use of JPrCP panels allowed major lane closures to be done at night, minimizing the impact to the community and the traveling public.
- Fabricated off site by a local manufacturer in a controlled environment
- Allowed higher quality control standards
- Allowed uniform curing of the panels that controlled/eliminated shrinkage cracking
- Allowed higher compressive strengths and plant acceptance that resulted in greater durability
- Decreased the need and frequency for future maintenance on this stretch of roadway
- Eliminated the use of vibratory equipment due to the proximity of historic buildings and aging underground utilities
- Allowed the use of variable depth milling to remove rutting and correct cross slope
The use of JPrCP panels greatly improved the constructability process while providing a long-term pavement solution in downtown Winder. The technology allowed GDOT to accelerate construction time, reduce the exposure to workers as well as the traveling public, and reduce congestion delays caused by excessive construction work zone time frames. This emerging technology was found to be more cost efficient than the option of removal and total reconstruction of the roadway.
I-94 Repair Project – Hudson, Wis.
About the project:
- Pavement rehabilitation pilot project, the first project incorporating JPrCP panels in Wisconsin
- Involved the repair of approximately 500 joints using 210 precast panels and 300 cast-in-place panels over a five-mile stretch of I-94
- Repairs were to be performed on the middle lane of I-94, which meant the middle lane and another lane on either side had to be closed down
- Work windows were from 11:00 p.m. to 6:00 a.m. (lowest traffic volumes)
The precast advantage:
- Each of the 210 panels was custom manufactured to each segment needing repair
- The majority of slabs weighed 10,000 to 11,000 lbs each, meaning that three to four slabs could be transported per load
- Each panel was numbered and sequenced on the truck to ensure efficient installation at the job site
- Open to traffic the next day
- Precast joints last twice as long as cast-in-place methods, eliminating the need for a second round of repairs
Andy Wieser, president and co-owner of Wieser Concrete Products Inc. based in Maiden Rock, Wis., the precast manufacturer, explained the process of slab replacement: “The contractor goes out to the project and measures each spot needing replacement, and then we make each slab to fit those measurements,” he said.
Once created, Wieser Concrete numbered the slabs in sequence and coordinated their placement on the truck for hauling to the job site. Everything was coordinated with the trucking company so that the slabs were stacked properly and wouldn’t have to be handled after delivery. “So everything from production to delivery to installation was all sequenced to match that location on the highway,” said Wieser.
Wieser reiterated how precast panels are particularly helpful in situations where the center lane of the highway cannot be shut down for more than a few hours at a time.
Randy Luedtke, an engineer with Wisconsin State DOT, stated that JPrCP technology is something that Wisconsin is going to have to use moving forward due to the numerous locations with lane restrictions.
The success of the I-94 project led directly to another repair project in Madison, Wis., using JPrCP technology:
Madison South Beltline Highway (USH 12)
About the project:
- Eight-mile section of 10-in.-thick JPrCP constructed between 1987 and 1989 is exhibiting isolated distress and in need of repair to extend its useful service life
- Six-lane urban freeway
- Carries approximately 120,000 vehicles per day
- High traffic volumes and lack of alternate routes necessitated keeping at least four lanes open at all times, and keeping all lanes open during the rush hours
- Patching the center lane requires a dual lane closure and is limited to a 7.5 hour work window
The precast advantage:
- Shortened the duration of construction
- Provided the lowest life cycle cost through improved durability
“After learning more about the technology through the May 2013 NPCA/ACPA webinar, various FHWA webinars, meeting with a precast manufacturer and a site visit to the Hudson project, we felt the technology was a good fit to solve our project challenges,” said David Layton, project manager with WisDOT Southwest Region. “Factoring in traffic control setup/teardown and cure time, you’re only left with three to four hours of production. With almost 400 patches on the center lane alone, this would eat up seven to nine weeks of the schedule and not leave enough time for other repairs.”
The need is now
JPrCP is an emerging technology with a lot of promise in the construction/transportation industry. Realizing the benefits of JPrCP will help the industry solve some of the issues with conventional construction methods for restricted project sites while keeping the disturbance to the traveling public at a bare minimum.
Evan Gurley is a technical services engineer with NPCA.
- American Road & Transportation Builders Association (artba.org)
- Georgia Department of Transportation Fact Sheet (winderdowntown.com/wp-content/uploads/2013/02/Fact-sheet-FINAL.pdf)
- U.S. Deportment of Transportation Federal Highway Adminstration (www.fhwa.dot.gov/hfl/projects/construction/)
- Ayers Associates (ayersassociates.com)