Page 329 - Planning and Design of Airports

Structural Design of Airport Pavements 287

departures of all aircraft. For flexible pavements, FAARFIELD will
estimate the total thickness of the pavement, including a minimum 2
in surface course. For rigid pavements, FAARFIELD will estimate the
slab thickness. In addition FAARFIELD will call for a minimum sub-
base thickness of 4 in for aircraft weighing 12,500 lb maximum gross
weight or greater.
Other than using flexible or rigid pavement structures, landing
facilities for light aircraft may be turf or an aggregate-turf mixture.
FAARFIELD also has capabilities for estimating the composition of
aggregate-turf mixtures.

Pavement Evaluation and Pavement
Management Systems
A pavement management system (PMS) is a mechanism for providing
consistent, objective, and systematic procedures for evaluating pave-
ment condition and for determining the priorities and schedules for
pavement maintenance and rehabilitation within available resource
and budgeting constraints. The pavement management system can
also be used to maintain records of pavement condition and to provide
specific recommendations for actions which may be required to main-
tain a pavement network at an acceptable condition while minimizing
the cost associated with pavement maintenance and rehabilitation.
A pavement management system evaluates present pavement
condition and predicts future condition through the use of a pave-
ment condition indicator. By projecting the rate of deterioration in
the pavement condition indicator and adopting some minimum
acceptable level for this indicator, a life-cycle cost analysis can be
performed for various maintenance and rehabilitation alternatives,
and a determination can be made of the optimal time for the applica-
tion of the most appropriate alternative. The rate of deterioration of a
pavement accelerates with time. By implementing a maintenance or
rehabilitation strategy to upgrade the pavement condition at the
proper time the overall cost of maintenance and rehabilitation can be
minimized. As noted by the FAA, the total annual cost to maintain or
rehabilitate a pavement in relatively poor condition can be 4 to 5 times
that of maintaining or rehabilitating a pavement in relatively good
condition.
An effective PMS for use at airports should include the following
components:
1. A systematic mechanism for regularly collecting, storing, and
retrieving the necessary data associated with pavement use
and condition
2. An objective system for evaluating pavement condition at
regular intervals