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Bridges & Structures

 

Bridge Scour and Stream Instability Countermeasures: Experience, Selection, and Design Guidance-Third Edition

Table 2.1

Table 2.1 STREAM INSTABILITY AND BRIDGE SCOUR COUNTERMEASURES MATRIX Countermeasure Characteristics
Countermeasure GroupFUNCTIONAL APPLICATIONS SUITABLE RIVER ENVIRONMENT MAINTENANCE INSTALLATION EXPERIENCE BY STATE DESIGN GUIDELINE REFERENCE*
Local Scour Contraction Scour Stream Instability Overtopping Flow River Type Stream Size Bend Radius Velocity Bed Material Ice/Debris Load Bank Slope Floodplain Estimated Allocation of Resources
Abutments Piers4 Floodplain and Channel Vertical Lateral Approach Embankments B = braided
M = meandering
S = straight		 W = wide
M = moderate
S = small		 L = long
M = moderate
S = short		 F = fast
M = moderate
S = slow		 C = coarse bed
S = sand bed
F = fine bed		 H = high
M = moderate
L = low		 V = very steep
S = steep
M = mild		 W = wide
M = moderate
N = narrow/none		 H = high
M = moderate
L = low
GROUP 1. HYDRAULIC COUNTERMEASURES
GROUP 1.A. RIVER TRAINING STRUCTURES
TRANSVERSE STRUCTURES
Impermeable spurs (jetties, groins, wing dams) halfmoon halfmoon newmoon newmoon fullmoon newmoon B, M W, M L, M checkmark checkmark checkmark checkmark checkmark M - L Widely Used DG 2
Permeable spurs (fences, netting) halfmoon halfmoon newmoon newmoon fullmoon newmoon B, M W, M L, M M, S S, F L checkmark checkmark H - M Widely Used DG 2
Transverse dikes newmoon newmoon newmoon newmoon fullmoon newmoon B, M W, M checkmark checkmark checkmark checkmark checkmark checkmark M - L NE
Bendway weirs/Stream barbs1 halfmoon halfmoon newmoon newmoon fullmoon newmoon M checkmark M, S checkmark checkmark checkmark checkmark checkmark L CO, ID, IL, MO, MT, OR, WA DG 1
Hardpoints newmoon newmoon newmoon newmoon fullmoon newmoon checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark L CA, ND, NE, SD CH 8
Drop structures (check dams, grade control) halfmoon halfmoon halfmoon fullmoon newmoon newmoon checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark M Widely Used DG 3
Embankment Spurs halfmoon newmoon halfmoon newmoon newmoon newmoon checkmark checkmark checkmark checkmark checkmark checkmark checkmark W L AK, OK
LONGITUDINAL STRUCTURES
Longitudinal dikes (crib/rock toe/embankments) halfmoon newmoon newmoon newmoon fullmoon halfmoon checkmark checkmark L, M checkmark checkmark M, L checkmark checkmark M - L AK, AZ, CA, OK, OR, MS CH 8
Retards halfmoon newmoon newmoon newmoon fullmoon newmoon checkmark checkmark L, M checkmark S, F L checkmark checkmark H - M Widely Used CH 8
Bulkheads fullmoon newmoon newmoon newmoon fullmoon newmoon checkmark checkmark checkmark checkmark checkmark checkmark V, S checkmark M Widely Used CH 8
Guide banks fullmoon halfmoon halfmoon newmoon halfmoon halfmoon checkmark W, M checkmark checkmark checkmark checkmark checkmark W, M M - L Widely Used DG 15
AREAL STRUCTURES/TREATMENTS
Jacks/tetrahedron jetty fields newmoon newmoon newmoon newmoon fullmoon newmoon B, M W, M L M, S S, F M, L checkmark W, M M Widely Used CH 8
Vanes newmoon halfmoon newmoon newmoon fullmoon newmoon B, M W, M L, M M, S S, F L checkmark checkmark H - M IA
Channelization halfmoon halfmoon newmoon newmoon fullmoon newmoon B, M checkmark checkmark checkmark checkmark checkmark checkmark checkmark M MS, MO, MT, TX CH 8
Flow relief (overflow, relief bridge) halfmoon halfmoon fullmoon newmoon newmoon fullmoon checkmark checkmark checkmark checkmark checkmark checkmark checkmark W M Widely Used
Sediment detention basin newmoon newmoon newmoon fullmoon newmoon newmoon checkmark checkmark checkmark checkmark C, S checkmark checkmark checkmark H - M Widely Used
GROUP 1.B. ARMORING COUNTERMEASURES
REVETMENTS AND BED ARMOR
Rigid
Soil cement fullmoon fullmoon halfmoon halfmoon fullmoon fullmoon checkmark checkmark checkmark checkmark S, F checkmark checkmark checkmark L AZ, CO, NM DG 7
Roller compacted concrete fullmoon halfmoon fullmoon fullmoon fullmoon fullmoon checkmark checkmark checkmark checkmark S, F checkmark checkmark checkmark L Widely Used
Concrete pavement halfmoon newmoon fullmoon halfmoon fullmoon halfmoon checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark M Widely Used
Rigid grout filled mattress/concrete fabric mat halfmoon newmoon halfmoon halfmoon fullmoon halfmoon checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark M GA, MA, MD, ME, SD, WA
Fully grouted riprap newmoon newmoon newmoon newmoon halfmoon newmoon checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark M AZ, CA, CT, ME, MI, TN CH 5
Flexible/articulating
Riprap fullmoon fullmoon halfmoon halfmoon fullmoon halfmoon checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark M Widely Used DG 4
Self launching riprap (windrow) newmoon newmoon newmoon newmoon halfmoon newmoon checkmark checkmark checkmark checkmark C,S checkmark V, S checkmark H - M GA, CA, IL, PA DG 4
Riprap fill-trench halfmoon newmoon newmoon newmoon fullmoon newmoon checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark M Widely Used DG 4
Gabions/gabion mattress2 fullmoon fullmoon halfmoon halfmoon fullmoon halfmoon checkmark checkmark checkmark checkmark S, F M, L checkmark checkmark M Widely Used DG 11
Wire enclosed riprap mattress (rail bank/sausage) fullmoon newmoon newmoon newmoon fullmoon newmoon checkmark checkmark checkmark M, S S, F M, L S, M checkmark M AZ, CO, NM DG 6
Articulated blocks (interlocking and/or cable tied) fullmoon fullmoon fullmoon halfmoon fullmoon fullmoon checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark M - L Widely Used DG 9
Concrete/grout mattress (fabric-formed) fullmoon halfmoon halfmoon fullmoon halfmoon checkmark checkmark checkmark M, S checkmark checkmark S, M checkmark M - L OR, CA, IA, IL, AZ DG 10
Partially grouted riprap fullmoon fullmoon halfmoon halfmoon fullmoon newmoon checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark L European practice DG 12
LOCAL SCOUR ARMORING
Riprap (fill/apron) fullmoon fullmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark H - M Widely Used DG 8, DG 14
Fully grouted riprap halfmoon newmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark H - M Widely Used CH 5
Concrete armor units (Toskanes, tetrapods, etc.)3 halfmoon halfmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark M checkmark M - L AZ, PA, NY, VA CH 5
Grout filled bags/sand cement bags fullmoon halfmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark M, L M checkmark H - M Widely Used DG 13
Gabions/gabion mattress2 fullmoon fullmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark S, F M, L S, M checkmark M FL, WA, TN, OR DG 11
Articulated blocks (interlocking and/or cable tied) fullmoon fullmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark M - L Widely Used DG 9
Sheet pile/cofferdam halfmoon halfmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark M - L CA, CT, FL, NH, WA
Partially grouted riprap fullmoon fullmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark S, M checkmark L European practice DG 12
GROUP 2. STRUCTURAL COUNTERMEASURES
FOUNDATION STRENGTHENING
Crutch bents/Underpinning newmoon fullmoon fullmoon fullmoon halfmoon N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark L FL, NC, OR, TX
Cross bracing newmoon fullmoon fullmoon fullmoon newmoon N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark L NC, FL, LA
Continuous spans newmoon fullmoon fullmoon fullmoon newmoon N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark L NC
Pumped concrete/grout under footing fullmoon fullmoon halfmoon halfmoon halfmoon N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark M Widely Used DG 13
Lower foundation fullmoon fullmoon fullmoon fullmoon fullmoon N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark L CA, OR, TX
PIER GEOMETRY MODIFICATION
Extended footings N/A fullmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark L Widely Used
Pier shape modifications N/A fullmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark M FL
Debris deflectors N/A fullmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark H - M CA, FL, NM, OR
Sacrificial piles/dolphins N/A fullmoon N/A N/A N/A N/A checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark H - M
GROUP 3. BIOTECHNICAL COUNTERMEASURES5
Vegetated geosynthetic products newmoon newmoon newmoon newmoon fullmoon halfmoon M, S M, S checkmark M, S checkmark M, L M, S checkmark H - M Widely Used CH 6
Fascines/woody mats newmoon newmoon newmoon newmoon fullmoon newmoon checkmark M, S checkmark M, S checkmark L M, S checkmark H - M Widely Used CH 6
Vegetated riprap newmoon newmoon newmoon newmoon fullmoon halfmoon checkmark checkmark checkmark checkmark checkmark checkmark M, S checkmark M - L Widely Used CH 6
Root wads newmoon newmoon newmoon newmoon fullmoon newmoon checkmark M, S checkmark M, S checkmark L M checkmark H - M Widely Used CH 6
Live staking newmoon newmoon newmoon newmoon fullmoon newmoon checkmark M, S checkmark M, S checkmark M, L M, S checkmark H - M Widely Used CH 6
GROUP 4. MONITORING
FIXED INSTRUMENTATION
Sonar scour monitor halfmoon fullmoon fullmoon fullmoon halfmoon newmoon checkmark checkmark checkmark checkmark checkmark L checkmark checkmark M CO, FL, IN, NY, VA, TX CH 9
Magnetic sliding collar fullmoon fullmoon fullmoon fullmoon halfmoon newmoon checkmark checkmark checkmark checkmark S, F checkmark checkmark checkmark M Widely Used CH 9
Float out device fullmoon fullmoon fullmoon fullmoon fullmoon fullmoon checkmark checkmark checkmark checkmark S, F checkmark checkmark checkmark L AZ, CA, NV CH 9
Sounding rods halfmoon fullmoon fullmoon fullmoon halfmoon newmoon checkmark checkmark checkmark M, S C M, L checkmark checkmark H AR, IA, NY CH 9
PORTABLE INSTRUMENTATION
Physical probes fullmoon fullmoon fullmoon fullmoon fullmoon newmoon checkmark checkmark checkmark M, S checkmark M, L checkmark checkmark L Widely Used CH 9
Sonar probes fullmoon fullmoon fullmoon fullmoon fullmoon newmoon checkmark checkmark checkmark M, S checkmark L checkmark checkmark L Widely Used CH 9
VISUAL MONITORING
Periodic Inspection fullmoon fullmoon fullmoon fullmoon fullmoon fullmoon checkmark checkmark checkmark checkmark checkmark M, L checkmark checkmark H Widely Used CH 2
Flood watch fullmoon fullmoon fullmoon fullmoon fullmoon fullmoon checkmark checkmark checkmark checkmark checkmark M, L checkmark checkmark H Widely Used CH 2

NOTES:

  1. There is limited but successful field experience using bendway weirs/stream barbs as stream instability countermeasures.
  2. Performance of welded vs. twisted wire, and PVC coated vs. uncoated wire gabions is not distinguished in the matrix.
  3. There is limited but successful field experience using concrete armor units for scour protection at bridge piers.
  4. Piers at new bridges cannot rely on countermeasures to reduce the design depths of foundation elements (Federal guidance).
  5. Biotechnical countermeasures are only intended for stream banks, not stream beds. This matrix assumes that any biotechnical treatments are fully grown, with well-established root systems. The toe of any streambank treatment should be reinforced with rock riprap or other armor material, as discussed in Chapter 6 of this document.
  6. See Chapter 3 for discussion of selection criteria for countermeasures.
  7. See Chapter 6 for discussion of biotechnical engineering countermeasures.
  8. See Chapter 8 for discussion of other countermeasures and case histories of performance.
  • fullmoon well suited/primary use
  • checkmark suitable for the full range of the characteristic
  • halfmoon possible application/secondary use
  • newmoon unsuitable/rarely used
  • N/A not applicable
  • CH# HEC-23 Chapter
  • DG# HEC-23 Design Guideline
Updated: 06/27/2017
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