FLOOD06847

• County: Statewide
• Basin: Statewide
• Title: Bridge Scour and Stream Instability Countermeasures
• Date: 7/1/1997
• Prepared By: Federal Highway Administration
• Floodplain - Doc Type: Educational/Technical/Reference Information

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Countermeasures were organized into groups based on their functionality with respect to
scour and stream instability. The three main groups of countermeasures are: hydraulic
countermeasures, structural countermeasures and monitoring. The following outline
identifies the countermeasure groups in the matrix:

Group 1. Hydraulic Countermeasures

. Group 1.A: River training structures

- Transverse structures
- Longitudinal structures
- Areal structures

. Group 1.B: Armoring countermeasures

- Revetment and Bed Armor
+ Rigid
+ Flexible/articulating
- Local armoring

Group 2. Structural Countermeasures

. Foundation strengthening
. Pier geometry modification

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Group 3. Monitoring

. Fixed Instrumentation
. Portable instrumentation
. Visual Monitoring

3.2 Countermeasure Groups

3.2.1 Group 1. Hydraulic Countermeasures

Hydraulic countermeasures are those which are primarily designed either to modify the flow
or resist erosive forces caused by the flow. Hydraulic countermeasures are organized into
two groups: river training structures and armoring countermeasures. The performance
of hydraulic countermeasures is dependent on design considerations such as filter
requirements and edge treatment, which are discussed in Sections 4.4.1 and 4.4.2,
respectively.

3.2.1.1 Group 1.A River Training Structures

River training structures are those which modify the flow. River training structures are
distinctive in that they alter hydraulics to mitigate undesirable erosional and/or depositional
conditions at a particular location or in a river reach. River training structures can be
constructed of various material types and are not distinguished by their construction
material, but rather, by their orientation to flow. River training structures are described as
transverse, longitudinal or areal depending on their orientation to the stream flow.

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