classification formula. Table 1-2 lists the minimum width requirements for one- and
two-lane bridges according to MLC. If a one-lane bridge meets all the requirements except
the minimum width for a certain classification, the classification is not downgraded. The
width is underlined, and appropriate travel restrictions are imposed. A two-lane bridge
must meet the minimum lane widths.
Table 1-2. Minimum Lane Width for Bridges
Minimum Width Between Curbs
Bridge
Classification
One Lane
Two Lane
4-12
2.75 m (9 ft 0 in)
5.50 m (18 ft)
13-30
3.35 m (11 ft 0 in)
5.50 m (18 ft)
31-60
4.00 m (13 ft 2 in)
7.30 m (24 ft)
61-100
4.50 m (14 ft 9 in)
8.20 m (27 ft)
f.
The overhead clearance is the minimum distance between the traveled way
and any obstruction above it. This figure is shown (in meters) to the left of the circle. Any
overhead clearance less than 4.3 meters is underlined. Unlimited overhead clearance is
indicated by the symbol for infinity (∞). Any overhead clearance less than 4.3 meters is
reported as an obstruction in the route classification formula.
1-15. Ford Symbols. Limited ford information is recorded on maps or overlays by means of
symbols (STANAG 2253) (Figure 1-16, page 1-12). All elements of the ford symbol are
separated by slashes. If any item of the ford symbol is unknown or undetermined, a
question mark is substituted for the required information.
a.
The geographical location of the ford is shown by an arrow that extends from
the ford symbol to the location of the ford on the map or overlay. The symbol may be drawn
on either side of the stream.
b.
For later reference, a serial number is assigned to each ford. Numbers must
not be duplicated within any one map sheet, overlay, or document. The number is recorded
to the extreme left top of the symbol.
c.
The ford type is annotated (with the letters V for vehicular or P for
pedestrian) after the serial number. The ford type is determined by the waterway's bottom
conditions, width, and water depth. Approaches are not considered in determining the ford
type. Table 1-3 is used to determine trafficability of the ford. Only the shallow, fordable
depth and the minimum width are used as criteria. Maximum desirable slope will not
determine the ford type.
d.
Normal stream velocity is placed after the ford type. The velocity is expressed
in meters per second (mps).
EN 5621
1-10
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