is bridges. Bridges are considered only in the route classification. Recon symbols are used to show
the nature of the obstruction on the route recon overlay. The most common ones are in FM 19-4.
Special Considerations. The effects of snow are not normally considered an obstruction to traffic flow
in route classification. This is because of the variables that are involved such as snow depth and the
availability of snow removal equipment. When snow blockage is regular, happens repeatedly, and is
serious, it is noted by adding the symbol (T) at the end of the formula. An example of such a situation
would be the Donner Pass in the Rockies.
Floods are treated in the same manner as snow. They are noted only if they happen regularly and are
serious. When that situation exists, it is indicated by adding the symbol (W) at the end of the formula.
For example, such conditions might be anticipated along tidal rivers.
Route Classification Formula Examples
A great deal about a route can be told from the route classification formula. It provides a summary of
the route's limitations. Here are a few examples, with explanations, to assist you in putting the previous
information together. It might be helpful to you to attempt to decipher them before reading the
explanation. Then read the explanation and check yourself.
Example 1: 20 ft/Z/40/oo
This formula describes a fair weather route (Z). The minimum traveled way is 20 feet. It has a military
load classification of 40. The overhead clearance is unlimited and it has no obstructions or special
conditions. Note that the first number specifies whether it is in feet or meters. If you had been directed
to check a route for double flow traffic, an obstruction (OB) would be included. The traveled way of 20
feet is sufficient only for single flow traffic.
Example 2: 6.7m/Y/30/Sm (OB)(W)
This formula indicates limited all weather route (Y) that has a traveled way of 6.7 meters. It has a
military load classification of 30. The lowest overhead clearance on the route is 5 meters. There is at
least one obstruction present. The overlay would have to be consulted to determine what it is. The
route is also subject to regular, repeated, and serious flooding.
Example 3: 7m/Y/50/4.6 (OB)
In this example, the route is a limited all weather route (Y) with a width of 7 meters. It has a military
load classification of 50. The overhead clearance is 4.6 meters. Meters were specified as the unit of
measure in the road width. It has an obstruction. The obstruction in this case may be that it is not
suitable for double flow traffic.
Example 4: 10.5m/X/120/5 (OB)(T)