TM 5820-4/AFM 885, Chap 4
cover culvert inlets, care must be taken to design
precast steel or of built-up, welded steel. Steel
the grate so that the inlet will not clog during
grates will be galvanized or bituminous coated.
periods of high water. Where curb inlet systems
Unusual inlet conditions will require special de-
are used, setbacks should be minimal, and grates
should be designed for hydraulic efficiency and
safe passage of vehicles. Hazardous channels or
38. Vehicular safety and hydraulically effi-
energy dissipating devices should be located out-
cient drainage practice.
side the designated recovery area or adequate
a. Some drainage structures are potentially
guard-rail protection should be provided.
b. It is necessary to emphasize that liberties
hazardous and, if located in the path of an errant
should not be taken with the hydraulic design of
drainage structures to make them safer unless it
of an accident. Inlets should be flush with the
is clear that their function and efficiency will not
ground, or should present no obstacle to a vehicle
be impaired by the contemplated changes. Even
that is out of control. End structures or culverts
minor changes at culvert inlets can seriously dis-
should be placed outside the designated recovery
rupt hydraulic performance.
area wherever possible. If grates are necessary to