(A) General. Bridges of primary benefit to the developer, as determined by the City Council, shall be constructed at the full expense of the developer without reimbursement from the city or county government. The sharing of expense for the construction of bridges not of primary benefit to the developer, as determined by the City Council, will be fixed by special agreement between the city or county government and the developer. The cost shall be charged to the developer pro rata, as the percentage of his or her land developed and so served.
(B) Definitions. For the purpose of this section, the following definitions apply unless the context clearly indicates or requires a different meaning.
BRIDGE. Constructed with abutments and superstructures, which are typically concrete, steel or other material. Since the superstructures are generally not an integral structural part of the abutments, and are therefore free to move, the hydraulic criteria for bridges is different than for culverts. BRIDGES are also usually constructed with earth or rock inverts, whereas culverts are typically the same material throughout the waterway opening.
CULVERT. A closed conduit for the passage of water under an embankment, such as a road, railroad, or delivery. The distinction between a CULVERT and a sewer is the means by which flow enters the conduit. Flow normally enters a CULVERT by an open channel, generally at a similar elevation and a culvert usually crosses a street.
(C) Culverts.
(1) Construction materials. Culverts shall be constructed of reinforced concrete or corrugated metal.
(3) Design frequency. Minimum design frequency for culverts shall be 100-year.
(4) Minimum size.
(a) Pipe culverts: 18-inch equivalent; and
(b) Box culverts: no less than three feet in height.
(5) Velocity limitations.
(a) In design of culverts both the minimum and maximum velocities must be considered. A minimum velocity of three feet per second at the outlet is required to assure a self-cleaning condition of the culvert.
(b) The outlet area shall include a headwall with wing walls or end-section in addition to the riprap protection if required. Where outlet velocities exceed six feet per second, erosion control measures shall be taken. Energy dissipaters shall be provided as required.
(6) Structural design. Culverts shall be design to withstand an HS-20 loading in accordance with the design procedures of AASHTO Standards Specifications for Highway Bridges and with pipe manufactures recommendations. In addition, the AASHTO maximum heights of cover for corrugated metal structures shall be followed. The minimum cover over the top of the pipe shall be 12 inches.
(7) Driveway crossings. Driveway culverts shall be sized to pass the 100-year ditch flow capacity without overtopping the driveway. The minimum size culvert shall be 18-inch pipe, or equivalent, where required, for all streets. Slopewalls shall be required per the standard detail drawings (see App. A to this chapter).
(8) Concrete end treatments. All culvert inlets and outlets shall have standard ODOT concrete end treatments.
(D) Bridges.
(1) Bridge sizing criteria. The sizing criteria set forth in division (C) above for culverts shall apply as follows.
(a) FREEBOARD is defined as the vertical clearance of the lowest structural member of the bridge superstructure above the water surface elevation of the design frequency flood. The minimum FREEBOARD shall be one foot for 100-year frequency flood.
(b) BACKWATER is defined as the rise in the flood water surface due to the restrictions created by the construction of the bridge. The maximum BACKWATER shall be one foot.
(2) Velocity limitations. The velocity limitations through the bridge opening are controlled by the potential abutment scour and subsequent erosion protection provided. Using riprap for the channel lining and/or protection of the abutments and wing walls, the maximum channel velocity is limited to 15 fps.
(3) Hydraulic analysis. The hydraulic design of bridge crossing shall be in accordance with the state’s Department of Transportation Drainage Design Manual, 1988.
(4) Inlet and outlet configuration.
(a) The bridge design shall include adequate wing walls of sufficient length to prevent abutment erosion and provide slope stabilization from the embankment to the channel.
(b) Erosion protection on the inlet and outlet transition slopes shall be protected from the erosive forces of eddy current.
(5) Criteria; compliance. Bridges shall be designed in accordance with AASHTO/ODOT criteria. Rails shall comply with ODOT standard details.
(2002 Code, § 153.081) (Ord. 230, passed 9-8-1986; Ord. 651, passed 10-26-2009)