TM 5-826-6/AFR 93-5
Figure A-19. Medium severity depression case 2
(c) High severity level (H). The depression can be readily observed, severely affects pavement riding
quality, and causes definite hydroplaning potential (see measurement criteria below) (fig. A-20).
Figure A-20. High seventy depression
(3) Measuring procedure. Depressions are measured in square feet of surface area. The maximum depth of
the depression determines the level of severity. This depth can be measured by placing a 10-foot straightedge across the
depressed area and measuring the maximum depth in inches. Depressions larger than 10 feet across must be measured
by either visual estimation or by direct measurement when filled with water.
Maximum Depth of Depression
Runways and
Taxiways and
Aprons
Seventy
High-Speed Taxiways
L
1/8 - 1/2 inch
1/2 - 1 inch
M
1/2 - 1 inch
1 - 2 inch
H
> 1 inch
> 2 inch
A-15
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