VIII. 1

1
VIII. Overview Of Design Guidelines

• A. Bridge Design Tips
• Use Computerized step-backwater model such as
  HEC-2, HEC-RAS or WSPRO
• Take cross sections 1) far downstream 2) at the
  face of the bridge 3) at the bridge opening 4)
  far upstream
• Utilize guidance (such as Hydraulics of Bridge
  Waterways) produced by Federal Highway
  Administration and/or the U.S. Army Corps of
  Engineers
• Utilize Scour Countermeasures such as provision
  of deep toe-downs on bridge piers and abutments
  or construction of spur dikes and jetties
• Meet minimum freeboard requirements listed in the
  literature

See these resources Various City/County Design
Manuals and CCDC-01 (5.4), CCDM-99 (1005),
CTDM-89 (9.5), FITD Class CD
2
Example Large Scale Bridge
3
Example Small Scale Bridge
4
VIII. Overview Of Design Guidelines

• B. Culvert Design Tips
• Consider Step-by-Step Procedures for Sizing
  Culverts
• See Literature for Explanations/Equations of
  Culvert Hydraulics
• Determine whether a culvert is under inlet or
  outlet control
• See Guidance for Culvert Inlet/Outlet Design and
  Protection
• Consider Countermeasures for Culvert
  Sedimentation and Erosion
• See Nomographs to simplify equation solving
• See guidance equations to evaluate the
  appropriateness of using a culvert in lieu of a
  bridge
• See guidance for culvert material selection

See these resources Various City/County Design
Manuals and CCDC-01 (5.1 to 5.3),CCDM-99 (1001 to
1004), CTDM-89 (11), YCDM-98 (8.2 to 8.4), FITD
Class CD
5
Example Small Culverts
6
Example Culvert Inlet and Outlet Protection
7
Example Culvert Inlet and Outlet Control Diagrams
8
Example Culvert Flow Types
9
Example Culvert Nomograph
10
VIII. Overview Of Design Guidelines

• C. Dip Crossing Design Tips
• Definition Crossings of watercourses which are
  designed to allow drainage to flow across
  roadways at-grade are commonly referred to as
  either at-grade or dip crossings (CTDM-89).
• Design Dip Crossings to have a 4 minimum
  cross-slope to reduce roadway sedimentation
• At a minimum, place a two-foot-deep cutoff wall
  along the upstream side of the dip crossing to
  protect against general scour
• Place a minimum 3-foot-deep cutoff wall
  downstream of the dip crossing to protect against
  local scour and channel degradation

See these resources Various City/County Design
Manuals, CTDM-89, FITD Class CD
11
Examples of Dip Crossings
12
VIII. Overview Of Design Guidelines

• D. Low-Flow Channel Crossing Design Tips
• Definition When the bottom of the channel
  cross section is too wide to efficiently convey
  the low-flow discharges which instead creates
  an incised low-flow channel that may meander back
  and forth across the bed of the channel... And,
  the meandering process can cause frequent and
  unnecessary scouring at the toe of the primary
  bankswhich can even destabilize totally lined
  channels. (CTDM-89).
• Possibly construct a low-flow channel within any
  larger channel in order to restrict the low flows
  to a designated area within the primary channel.
• The designed low-flow channel should be designed
  such that the unit discharge associated with the
  2-year storm event is the same as
  pre-construction conditions.

See these resources Various City/County Design
Manuals, CTDM-89, FITD Class CD
13
Example Low Flow Channel
14
VIII. Overview Of Design Guidelines

• E. Other Design Topics
• Design Guidance are Similarly Available for the
  Following
• Levee Systems

See this resources FITD Class CD
15
VIII. Overview Of Design Guidelines

• E. Other Design Topics
• Levee System Illustration

Streams with well-developed natural levees tend
to be of constant width and have low rates of
lateral migration. Well-developed levees usually
occur along the lower courses of streams or where
the floodplain is submerged for several weeks or
months a year. If the levee is breached, the
stream course may change through the breach.
16
VIII. Overview Of Design Guidelines

• E. Other Design Topics
• Design Guidance are Similarly Available for the
  Following
• Levee Systems
• FEMA Requirements

See this resources FITD Class CD
17
VIII. Overview Of Design Guidelines

• E. Other Design Topics
• Design Guidance are Similarly Available for the
  Following
• Levee Systems
• FEMA Requirements
• Channelization

See this resources FITD Class CD
18

• Channelization Illustration

19
VIII. Overview Of Design Guidelines

• E. Other Design Topics
• Design Guidance are Similarly Available for the
  Following
• Levee Systems
• Channelization
• Super-Elevation

See this resources FITD Class CD
20
VIII. Overview Of Design Guidelines

• E. Other Design Topics
• Levee System
• Channelization
• Super-Elevation Illustrations

Because of the change in flow direction which
results in centrifugal forces, there is a
superelevation of the water surface in bends. The
water surface is higher at the concave bank than
the convex bank.