Flexibility

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Introduction

Asphalt is flexible, adaptable, versatile, customizable and ready to meet just about every pavement need.  

Quick Construction 
Americans want well-maintained and functional roads, but they don’t want to waste time and money hemmed up in traffic caused by construction. The ability to construct and maintain roads quickly gives asphalt pavements the performance motorists require. During some phases of construction, and more importantly during maintenance operations, a road that is being worked on can be opened as soon as the pavement reaches a specified temperature and state of compaction. With asphalt, there is no lengthy curing period during which the road is closed to traffic even though construction is not active.

Standing Up to Mother Nature 
Asphalt is the best pavement option for hazardous weather conditions. For example, one type of asphalt surface, known as open-graded friction course (OGFC), allows rainwater to drain through the surface layer and off to the sides while still providing good skid resistance.1 This reduces the amount of splash and spray produced by vehicles, improving visibility and safety. Similarly, high-performance, rut-resistant stone-matrix asphalt mixes have been shown to improve surface drainage and increase friction during wet weather.2 

Also, because asphalt pavements are generally darker in hue, they require less salt or other deicing treatments to ensure clear winter roadways compared to light colored pavements.3,4 In fact, at pavement temperatures below 15°F, the use of deicing salts on snow-covered roadways and bridges are not as effective and additional chemicals are often required,5  which can have a negative environmental impact.6 When deicers are needed, they generally do less damage to asphalt pavements than other road surfaces.

The darker color can also provide greater contrast with white and yellow stripes, increasing the visibility of pavement markings.8 All types of pavement marking systems can work well on asphalt pavements, and there is evidence that markings remain effective longer on asphalt10 even in heavy snow areas.11 For thermoplastic markings, in particular, asphalt pavements provide a tighter, stronger bond than concrete pavements.12 

Case Study

Asphalt Flexibility Key in Rebuild of U.S. 98 After Hurricane Michael

Anderson Columbia Co. Inc. is working seven days per week to repair a 40-mile stretch of highway thrashed by a historic storm. 

By Chuck MacDonald

People driving U.S. 98 in Franklin County Florida are often captivated by the view of the Gulf of Mexico as they travel the Florida panhandle from Tampa to Panama City, Pensacola, and beyond. That picturesque view changed dramatically on Oct. 10, 2018, when Hurricane Michael crashed inland with top speeds of 155 mph. This Category 4 hurricane caused billions in damages and destroyed homes, vehicles, and infrastructure. It was the third-most intense Atlantic hurricane to hit land in U.S. history.

One of the casualties of the storm was U.S. 98. Hurricane Michael tore gaping holes in the pavement, rendering this vital lifeline for many communities undrivable. The Florida DOT quickly convened a bidding process to fix the road. Anderson Columbia Co. Inc. (ACCI), a large road-building operation with offices in Florida and Texas, was awarded the job. ACCI leaders were aware of the complexity of doing this kind of work, having completed a large hurricane relief rebuild in Walton County Florida in 2013.

Still the project was daunting.  The storm had gouged huge holes in the highway, one of them 500 feet long. Many others were 20 feet long and most filled with all manner of debris including sand, wood from demolished houses, and even guard rail shredded by the storm. The paving project required work on a 40-mile stretch of highway, with 15 miles badly roughed up by the storm. 

Asphalt was specified for the project in part for its flexibility.

Brad Herring, who has been with ACCI for 20 years, was the general supervisor for the project. “Because this was a two-lane highway, work had to be completed for the day, then turned back to traffic almost immediately,” he said. “We were also not allowed to do night paving since people’s homes were nearby the project. Concrete would not have been suitable for the project because we would have had to wait for the material to firm up before turning the road over to traffic. People simply could not wait that long to be denied use of this vital roadway.” 

After the first lift of asphalt, drivers could resume the work of rebuilding their lives after the hurricane, rather than try to dodge dangerous gaps in the road. Once ACCI workers cleared the debris, they placed 18 inches of graded aggregate base granite stone topped with a 1.5-inch layer of asphalt composed of 12.5 polymer asphalt with granite stone. A second 1.5-inch layer will be added later for smoothness. This is the Florida DOT spec, one that ACCI has used often. 

Another challenge for the team was the relative remoteness of the section. “There were not even grocery stores nearby,” said Herring. “So, when we came from the asphalt plant, which was about an hour away in Panama City, we had to bring everything with us.” ACCI also had to rent property for the project in order to park equipment such as bulldozers and excavators.

The weather was an issue as well. “It was 30 degrees here recently, unusual weather for Florida, and we are not allowed to pave in that temperature,” said Herring. “Then, of course, we have frequent rains, which can also limit us.”

Despite these conditions, the ACCI team has continued to keep its seven-day-per-week schedule. The team is still early in the project and later will rehab the shoulders as well as construct shoreline protection and guard rail patches. The initial project is slated to require seven months while rehab of the entire 40 miles will require five years. 
  
Writer bio: Chuck MacDonald is a writer living in Annapolis, Md. He has been a frequent contributor to projects for NAPA and other organizations.

  1. Putman, B.J. (2012). Evaluation of Open-Graded Friction Courses: Construction, Maintenance, and Performance. Report FHWA-SC-12-04. Clemson University, Clemson, South Carolina.

  2.  NCAT (2009). Hot Mix Asphalt Materials, Mixture Design, and Construction, Third Edition. NAPA Research and Education Foundation, Lanham, Maryland.

  3. TranSafety (1997). Using Salt and Sand for Winter Road Maintenance. Road Management & Engineering Journal.

  4. Cuelho, E., J. Harwood, M. Akin & E. Adams (2010). Establishing Best Practices for Removing Snow and Ice from California Roadways: Final Project Report. Western Transportation Institute, Montana State University – Bozeman, Bozeman, Montana.

  5. MnDOT (2013). MnDOT District 1 2013 Winter State Highway Maintenance White Paper — Fact Sheet. Minnesota Department of Transportation, St. Paul, Minnesota.

  6. Langen, T. A., M. Twiss, T. Young, K. Janoyan, J.C. Stager, J. Osso Jr., H. Prutzman, and B. Green (2006). Environmental Impacts of Winter Road Management at the Cascade Lakes and Chapel Pond. Clarkson Center for the Environment, Clarkson University, Potsdam, New York.

  7. Sumsion, E.S., and W.S. Guthrie (2013). Physical and Chemical Effects of Deicers on Concrete Pavement: Literature Review. Report UT-13.09. Utah Department of Transportation, Salt Lake City, Utah.

  8. Debaillon, C., P. Carlson, Y. He, T. Schnell, and Fuat Aktan (2007). Updates to Research on Recommended Minimum Levels for Pavement Marking Retroreflectivity to Meet Driver Night Visibility Needs. Report FHWA-HRT-07-059. Federal Highway Administration, McLean, Virginia.

  9. Masliah, M., G. Bahar, T. Erwin, and E. Tan (2005). Towards Improved Management of Pavement Markings and Markers. Presented at the 2005 Annual Conference of the Transportation Association of Canada, Calgary, Alberta.

  10. Migletz, J., & J. Graham (2002). NCHRP Synthesis of Highway Practice 306: Long-Term Pavement Marking Practices. Transportation Research Board of the National Archives, Washington, D.C.

  11. Lynde, McG. (2006). Evaluation of Inlaid Durable Pavement Markings in an Oregon Snow Zone. Report FHWA-OR-DF-06-10. Oregon Department of Transportation, Salem, Oregon.

  12. TxDOT (2004). Pavement Marking Handbook, Revised August 2004. Texas Department of Transportation, Austin, Texas.