Regulated Rivers - Hydro-Environmental Analysis: Freshwater Environments - page 55

3.2.3 c uLVertS
Culverts are commonly used, hydraulically short conduits that are designed to transport water from
one side to the other of a roadway, railroad, levee, or other structure. Culverts can be made of a vari-
ety of materials, including corrugated metal, concrete (reinforced or not), and thermoplastic pipe
and there may be one or multiple barrels to the culvert (see Figures 3.12 and 3.13).
Engineers design culverts to pass a speciic design high-low discharge, as well as to maintain
lows under low-low conditions. Part of the hydraulic design process is to determine conditions
where the inlet, outlet, or both are submerged. A typical low-low design is for inlet control, where
the low capacity of the culvert entrance is less than the low capacity of the culvert barrel. Under

FIGURE 3.12 “Open-bottom,” arched culvert over Thunder Brook, Massachusetts, that enhances ish
passage. (From Massachusetts Division of Ecological Restoration.)

FIGURE 3.13 Precast concrete box culvert. (Courtesy of the American Concrete Industries.)