Page 247 - Planning and Design of Airports

Geometric Design of the Airfield 211

maximum change in longitudinal gradient is 1.5 percent. In addition,
for runways that are equipped to be used in bad weather, the gradient
of the first and last quarter of the length of the runway must be very
flat for reasons of safety. Both the ICAO and the FAA require that this
gradient not exceed 0.8 percent. In all cases it is desirable to keep both
longitudinal grades and grade changes to a minimum.
Longitudinal slope changes are accomplished by means of vertical
curves. The length of a vertical curve is determined by the magnitude of
the changes in slope and the maximum allowable change in the slope of
the runway. Both these values are also listed in Tables 6-11 and 6-12.

Aerodrome Code Number
1 2 3 4
Runway longitudinal
Gradient (%)
Maximum 2.0 2.0 1.5 * 1.25 *
Maximum change 2.0 2.0 1.5 1.5
Maximum effective † 2.0 2.0 1.0 1.0
Vertical curve (m)
Minimum length of curve ‡ 75 150 300 300
Minimum distance between 50 50 150 300
points of intersection §
Runway strips
Gradient (%)
Maximum longitudinal 2.0 2.0 1.75 1.5
Maximum transverse 3.0 3.0 2.5 2.5
Aerodrome Code Letter
A B C D E
Runway transverse gradient (%)
Maximum 2.0 2.0 1.5 1.5 1.5
Minimum 1.0 1.0 1.0 1.0 1.0
Shoulder transverse gradient (%)
Maximum 2.5 2.5 2.5 2.5 2.5

* May not exceed 0.8 percent in the first and last quarter of runway for aerodrome code
number 4 or for a category II or III precision instrument runway for aerodrome code
number 3.
† Difference in elevation between high and low point divided by runway length
‡ For each 1 percent change in grade.
§ Distance is multiplied by sum of absolute grade changes in percent minimum length is 45 m.
Source: International Civil Aviation Organization [3].
TABLE 6-11 Runway Surface Gradient Standards