An obstruction exists for double flow-traffic when the width is less than 7.3 meters for wheeled vehicles
or less than 8 meters for tracked.
Route Type. In the route classification formula, routes are designated by their ability to withstand
weather. Which of the classification symbols is used in the formula is based on the worst section of
road on the route. Three symbols are used. The symbols and the type road they represent have been
standardized among the NATO nations (STANAG 2174). They are:
Type X is a route that can be used in all kinds of weather without greatly reducing the amount
of traffic it can carry.
Type Y is also an all weather route, but has only a limited capacity for traffic during bad
weather. These roads usually do not have waterproof surfaces. Periods of rain, snow, or
extreme temperatures will require that traffic be substantially reduced. They may be closed
for periods of up to one day in bad weather. In bad weather, heavy use of the road may
cause it to become impassable. The road would then require major road repair efforts to
restore it to normal use.
Type Z is a fair weather route. It is one that very quickly becomes unusable in bad weather.
During periods of bad weather, traffic may have to be halted for long periods of time. It has a
non-waterproof surface, such as packed clay. Even in fair weather, its ability to carry heavy
traffic is limited.
Military Load Classification. The military load classification system is a method of rating the load-
bearing classification for vehicles, roads, and bridges. For vehicles, it is based on the weight, type
(wheeled, tracked), and the effect of the vehicle on roads. For roads and bridges, it is based on their
ability to carry certain types of traffic without causing major damage to the roads or bridges. The
engineers classify roads and bridges based on their physical characteristics, the type and flow of traffic,
effects of weather, and other special conditions. One of the items you will need to know before
Classification numbers for both roads and bridges are usually located at the bridges. This is because
the bridge is normally the weakest point on the road. Bridges (and rafts) have circular signs indicating
the classification and other information.
A full NATO bridge sign will be a large yellow rectangle with black symbols.
In the center will be a large circle divided into three parts. In the upper third of the circle will be a
smaller circle. To the left (shaded) side of the circle is the two way wheeled classification. On the right
(unshaded) is the one way wheeled classification. A small rectangle is centered in the middle third of
the circle. This indicates the same information for tracked vehicles. In the bottom third of the symbol is
the bridge serial number. The width of the traveled way of the bridge is placed below the large circle.