Innovation Spotlight: Bush Intercontinental Airport Conducts First “Stringless Pave”

Use of software-guided paving systems bring host of benefits

Safer. Less guesswork. A more efficient use of labor hours.

In October, Houston’s Bush Intercontinental Airport for the first time used “stringless paving” technology at our Taxiway WA/WB Rehabilitation Project.

“String lines have traditionally been used to control paving machine elevation and grade steering,” explains Houston Area Manager Mike Zanella. “Stringless paving, also known as 3-D paving, is an innovative process where noncontact electronic guidance systems are used.”

In stringless paving there are no pins, hubs, sensors or other devices previously used to guide paving. “This produces significant savings in time and labor,” says Zanella. String-guided paving typically requires five feet of 

clearance on each side of the paving machine. With stringless paving, that is reduced to as little as a foot, providing easier access for workers and trucks.

There are three major parts to the process:

• Developing the pavement surface model(s). Bush Airport’s engineers provided Flatiron with the models to use for the paving.
• Transfer of the model(s) to the paving machine’s onboard computer.
• Establishment of survey control points along the paving zone. A series of total stations and/or GPS systems communicate with the software to guide the paving machine.

Stringless paving also makes the site safer for workers

“This technology enhances safety on the grade by reducing or eliminating trip hazards from hubs, stakes or the string itself,” explains Zanella. “It also improves access to the grade in front of the paving machine, reducing choke points and other dangers from delivery vehicles backing up to the paving site.”

Those aren’t the only benefits to using this innovative technique. “String lines are constantly at risk of sustaining damage that can affect paving accuracy,” Zanella explains. “They get moved around for different operations, for example. Weather can also make the strings (actually fine wire) expand and contract.” The lines require frequent maintenance to function properly. Stringless paving eliminates the need for that.

Finally, there’s a sustainability angle to using stringless paving. The software is more accurate than string, meaning less risk of wasted concrete.