Type Y. This is a limited all-weather route that with reasonable
maintenance can be kept open in all weather but to less than
maximum traffic capacity. The roads that form this route type usually
do not have waterproof surfaces. The roads are considerably affected
by precipitation and/or temperature changes. The route may be closed
for short periods of up to one day due to adverse weather conditions.
Continued use of this route in adverse conditions would probably lead
to complete collapse of the road.
Type Z. This is a fair-weather route that quickly becomes impassable
in adverse weather. This type of route is so seriously affected by
adverse weather conditions that it may remain closed for long periods.
Improvement of such a route can only be achieved by construction or
realignment.
c.
Military Load Classification. Friendly forces must make maximum use of
existing routes. To do this, the military load carrying capacity of the routes for a basic
military road must be classified. The MLC assigns whole numbers to vehicles, bridges,
roads, and routes. Vehicle classifications are determined by weight, type, and effect on
routes. Bridge, road, and route classifications are determined by physical characteristics,
type and flow of traffic, effects of weather, and other special conditions. Regardless of traffic
type or flow, the lowest bridge MLC number determines the MLC of the route. If no bridge
is located on the route, the worst section of the route governs the classification.
d.
Overhead Clearance. Overhead clearance is the vertical distance between the
road surface and any obstruction over it that denies use of the route/road to all vehicles or
loads that exceed this height. If clearance is unlimited, symbolize it by using ∞ in the route
classification formula.
e.
Obstructions. Route obstructions are factors that restrict the type, amount, or
speed of traffic flow. Route obstructions are indicated in the route classification formula by
the abbreviation OB. If an obstruction is shown in the route classification formula, the
route reconnaissance overlay will show the exact location and nature of the obstruction.
The following obstructions must be reported with an OB in the route reconnaissance
formula:
Overhead obstructions with an overhead clearance of less than
4.3 meters.
Slopes of 7 percent or greater.
Curves with a radius of 25 meters or less.
Fords or ferries.
Reduction in traveled-way widths that are below the standard
minimum prescribed for the type of traffic flow.
EN 5621
2-4
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