Airport Business - 26

RUNWAY MATTERS
AUTHOR Kristin Dispenza

Runway Grooving:

A GOOD SOLUTION TAKES OFF

GROOVING AIRPORT runways is common practice
in the United States. The U.S. Federal Aviation
Administration (FAA) recommends grooving for all
airport projects funded with federal grants, which
represents most projects.
Similarly, U.S. Department of
Defense facilities are increasingly
specifying new, reconstructed or
resurfaced runways to be grooved. In
Canada, however, there has been limited
use of runway grooving. In recent years
this situation has been changing, due
to the overwhelming evidence that
grooving is a proven strategy for reducing
the risk of hydroplaning and improving
runway safety. There are three basic
types of airplane hydroplaning and their
underlying physical conditions as follows:
* Dynamic hydroplaning occurs at
relatively high speeds when there is a
film of water on the runway that is at
least 1/10-inch deep. The water layer
resists displacement when the water
pressure equals the weight of the
airplane; the tire lifts off the runway
surface and stops rotating. The airplane
loses braking and directional control.
* Reverted rubber (steam) hydroplaning
occurs during heavy braking that results
in a prolonged locked-wheel skid. This
can happen even if there is only a thin

film of water on the runway. The
skidding tire generates enough heat to
cause the contact patch of rubber to
revert to its original uncured state. This
reverted rubber acts as a seal between
the tire and the runway, trapping water.
The water then heats and is converted
to steam, exerting force and lifting the
tire off the runway. When the airplane
eventually slows and tires reconnect

ABOUT THE AUTHOR
KRISTIN DESPENZA

Kristin Dispenza is an Account Manager
with Advancing Organizational Excellence
and develops trends articles, case studies
and other PR materials. She received a
Bachelor of Science degree from The Ohio
State University College of Engineering/
School of Architecture and has more
than 20 years of writing and editorial
experience. She can be reached at kristin.
dispenza@aoeteam.com.

26 \ AIRPORTBUSINESS / APRIL 2019

with the runway surface, the airplane
skids. Dynamic hydroplaning, which
often causes the pilot to lock brakes, can
lead to reverted rubber hydroplaning.
* Viscous hydroplaning is caused by the
viscosity of water and it can happen
when there is only a thin film - no
more than one thousandth of an inch -
on the runway. In viscous hydroplaning,
the tire cannot penetrate the f luid
and the tire rolls on top of the film.
This can occur at a much lower speed
than dynamic hydroplaning, and is
a problem on smooth surfaces such
as a touchdown area coated with the
accumulated rubber of past landings.
In any of these situations, the friction

Before
and after
grooving
during
rain event
that
occurred
during
trial
section on
Oct. 30,
2017
COURTESY OF THE
GOVERNMENT OF
CANADA



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