News Articles

 

When the Rubber Meets the Runway

The AOS Team Assists with Relief Efforts Following the 7.0 Earthquake that Shook Haiti

Chemical Rubber Removal System
Figure 1.  AOS Research Group’s Chemical Rubber Removal System

Rubber Removal Team
Figure 2.  Rubber removal team members.

Before Removal Process
Figure 3.  Runway before the rubber removal process.

After Removal Process
Figure 4.  Runway after the rubber removal process.

By: Peggy Allen, ARA Engineering Science Division

According to a report by the Australian Transport Safety Bureau (ATSB), between 1998 and 2007, 141 runway excursion accidents happened worldwide.  Included in these accidents were aircraft running off the end of the runway or departing the side of the runway, which resulted in 550 fatalities.  Over 85 percent of these incidents took place during landings.  There are several factors that contribute to aircraft runway accidents, however, runway rubber build-up is one that is easy to recognize and reasonably inexpensive to correct.

How Rubber Builds Up on Runways

When an aircraft lands, the tires are not spinning.  The friction from the tires and the pavement surface causes a chemical reaction, transforming the rubber into a sticky substance that hardens and becomes very slick when wet.  Each time an aircraft lands, over a pound of this substance (from each tire) is spread over the runway in thin layers creating the "lasagna-effect."  After aircrafts repeatedly land, this substance builds up over time and the groves on the runway are filled and the surface becomes slick — making landing, stopping and water runoff quite difficult and unsafe.

As indicated by Frank W. Hardy, a veteran pilot and writer for Suite 101, on July 17, 2007, TAM Flight 3054 crashed in São Paulo, Brazil, taking the life of hundreds.  An eyewitness reported that the runway was wet from rain and rubber deposits were so thick that an aircraft could hydroplane on a sunny day.

The Bottom Line

The major concern regarding the build-up of rubber deposits on airfields is safety.  According to the Suite 101 article "The World's Dangerous Airports," Frank W. Hardy points out that pilots are more concerned about the runway than any of the cosmetic changes that take place at airports over time.  Pilots profoundly rely on the runway to be in good condition to properly and safely land their aircrafts.

Techniques to Remove Rubber Deposits from Runways

FAA AC 150-5320-12C provides airport personnel with guidance on how to construct, maintain and assess skid-resistant airport pavement surfaces.  It describes common rubber removal techniques and provides guidance on how to accomplish this task.

Some techniques commonly used to remove rubber deposits from runways include waterblasting, chemical (Figure 1), shotblasting, mechanical, and high pressure/ultra-high pressure water.  ARA's Aircraft Operating Surfaces (AOS) Research

When the team arrived, they immediately noticed the build-up on the runway.  The build-up was extreme in comparison to rubber removal tasks that they worked with previously.  One team member stated that he had never seen rubber build-up to the magnitude that was observed on the runway at Toussaint Louverture International Airport.    The team believes the runway has never had rubber removed since the airport opened over 40 years ago. 

Since the January 2010 earthquake, the airport traffic increased from 13 flights per day to approximately 200 flights.  Photographs in Figure 3 and 4 show how the runway looked before and after the rubber removal technology was applied and what a difference the AOS team made on the city of Port-au-Prince and the country of Haiti.  Keep in mind, the major concern regarding the build-up of rubber deposits on airfields is safety and now the airfield is safe for landings and take-offs due to the assistance of the AOS team. 

This project not only helped Haiti's recovery as part of the Operation Unified Response, but also helped demonstrate the capabilities of the AOS Research Group while providing an opportunity to evaluate the system under real conditions.  Recognizing the AOS Research Group's expertise in pavement friction research, friction testing and runway rubber removal, the group is currently developing/evaluating ultra-high pressure and high-pressure water rubber removal systems to provide a number of options based on the client's needs.

The AOS Research Group provides research and development (R&D) capabilities to the Department of Defense though a contract with the Air Force Research Laboratory.  The Group used the chemical technique on the runway at Port-au-Prince's Toussaint Louverture International Airport in Haiti. 

The chemicals that the team used were environmentally safe and effective in cleaning rubber deposits from the surface.  The chemicals were sprayed onto the airfield and then scrubbed, brushed and worked into the rubber deposits for approximately four hours. The chemicals loosened the sticky rubber buildup into a soft gel that was then removed from the runway with a brush and water onto the shoulders of the runway.

The team chose the chemical process for the following reasons:

  • It is time efficient
  • It does not damage the pavement surface, it only softens and removes the rubber build up
  • The work can be accomplished using limited staff and equipment, which saves on cost

AOS Research Group's Story

Air Force Civil Engineer Support Agency (AFCESA) personnel went to Haiti to evaluate runway condition at Toussaint Louverture International Airport in Port-au-Prince after the U.S. took charge in January 2010 following the 7.0 magnitude earthquake.  It was discovered at this time that the runway had medium to medium/heavy rubber build-up that could be a safety hazard if not removed.  A contractor quoted $500,000 to airport officials to clean the runway.   AOS Research Group (a part of ARA's Engineering Science Division) at Tyndall Air Force Base was asked by AFCESA and Southern Command to clean up the build-up due to the unique capability inherent with the group. 

The AOS Research Group has developed a C-130 deployable chemical rubber removal system that is light, compact and requires no in-theater support other than fuel and water.  AFCESA provided $125,000 in Research and Development funds to evaluate the rubber removal system in actual expeditionary environment.  Four team members (Figure 2) traveled to Haiti and used the rubber removal technology to remove rubber build-up from the runway.  In three days (approximately three eight hour shifts) they cleared 125,000 square feet on the west end of the runway and 75,000 square feet on the east end. 

When the team arrived, they immediately noticed the build-up on the runway.  The build-up was extreme in comparison to rubber removal tasks that they worked with previously.  One team member stated that he had never seen rubber build-up to the magnitude that was observed on the runway at Toussaint Louverture International Airport.    The team believes the runway has never had rubber removed since the airport opened over 40 years ago. 

Since the January 2010 earthquake, the airport traffic increased from 13 flights per day to approximately 200 flights.  Photographs in Figure 3 and 4 show how the runway looked before and after the rubber removal technology was applied and what a difference the AOS team made on the city of Port-au-Prince and the country of Haiti.  Keep in mind, the major concern regarding the build-up of rubber deposits on airfields is safety and now the airfield is safe for landings and take-offs due to the assistance of the AOS team. 

This project not only helped Haiti's recovery as part of the Operation Unified Response, but also helped demonstrate the capabilities of the AOS Research Group while providing an opportunity to evaluate the system under real conditions.  Recognizing the AOS Research Group's expertise in pavement friction research, friction testing and runway rubber removal, the group is currently developing/evaluating ultra-high pressure and high-pressure water rubber removal systems to provide a number of options based on the client's needs.

The AOS Research Group provides research and development (R&D) capabilities to the Department of Defense though a contract with the Air Force Research Laboratory.  The group

develops solutions for near-, mid- and long-term requirements for current and future aircrafts on AOS by advancing the body of knowledge.  Near- and mid-term problems are solved by developing advanced AOS materials and by progressing nondestructive evaluation (NDE) techniques.  Long-term problems are addressed by advancing the state-of-the-art in materials science and technology (S&T).  AOS Research Group's capabilities can be categorized as (1) Innovative R&D Practices, (2) AOS Materials Development, (3) Agile Combat Support, (4) AOS Evaluation and Assessment Capabilities, and (5) Airlift Packages.  Dr. Athar Saeed, PE, is the AOS Research Group Lead of ARA's Engineering Science Division.