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Scour Critical Bridge - Plan of Action

FHWA Revised POA Template

Word Version (174 kb)

1. GENERAL INFORMATION
Structure number: 
City, County, State: 
Waterway: 
Structure name: 
State highway or facility carried: 
Owner: 
Year built: 
Year rebuilt: 
Bridge replacement plans (if scheduled): 
Anticipated opening date: 
Structure type:___ Bridge / ___ Culvert
Structure size and description: 
Foundations:___ Known
  • Type: ____________________
  • Depth: ___
___ Unknown
Subsurface soil information (check all that apply):___ Non-cohesive / ___ Cohesive / ___ Rock
Bridge ADT: 
Year/ADT: 
% Trucks: 
Does the bridge provide service to emergency facilities and/or an evacuation route?:___ Yes / ___ No
If so, describe: 
2. RESPONSIBILITY FOR POA
Author(s) of POA (name, title, agency/organization, telephone, pager, email): 
Date: 
Concurrences on POA (name, title, agency/organization, telephone, pager, email): 
POA updated by (name, title, agency, organization): 
Date of update: 
Items update: 
POA to be updated every:___ Months
Date of next update: 
3. SCOUR VULNERABILITY
Current Item 113 Rating:___ 3 / ___ 2 / ___ 1 / ___ Other: ____________________
Source of Scour Critical Rating:___ Observed / ___ Assessment / ___ Calculated / ___ Other: ____________________
Scour Evaluation Summary: 
Scour History: 
4. RECOMMENDED ACTION(S) (see Sections 6 and 7)
 RecommendedImplemented
Increased Inspection Frequency:___ Yes / ___ No___ Yes / ___ No
Fixed Monitoring Device(s):___ Yes / ___ No___ Yes / ___ No
Flood Monitoring Program:___ Yes / ___ No___ Yes / ___ No
Hydraulic/Structural Countermeasures:___ Yes / ___ No___ Yes / ___ No
5. NBIS CODING INFORMATION
 CurrentPrevious
Inspection date:  
Item 113: Scour Critical:  
Item 60: Substructure:  
Item 61: Channel & Channel Protection:  
Item 71: Waterway Adequacy:  
Comments: (drift, scour holes, etc. - depict in sketches in Section 10):  
6. MONITORING PROGRAM
  • ___ Regular Inspection Program
    • ___ w/surveyed cross sections
    • Items to Watch: ____________________
  • ___ Increased Inspection Frequency of ___ Months
    • ___ w/surveyed cross sections
    • Items to Watch: ____________________
  • ___ Underwater Inspection Required
    • Items to Watch: ____________________
  • ___ Increased Underwater Inspection Frequency of ___ Months
    • Items to Watch: ____________________
  • ___ Fixed Monitoring Device(s)
    • Type of Instrument: ____________________
    • Installation location(s): ____________________
    • Sample Interval: ___ 30 Min ___ 1 Hr ___ 6 Hrs ___ 12 Hrs ___ Other: __________
    • Frequency of data download and review: ___ Daily ___ Weekly ___ Monthly ___ Other: __________
    • Scour alert elevation(s) for each pier/abutment: ____________________
    • Scour critical elevations(s) for each pier/abutment: ____________________
    • Survey ties: ____________________
    • Criteria of termination for fixed monitoring: ____________________
  • ___ Flood Monitoring Program
    • Type:
      • ___ Visual inspection
      • ___ Instrument (check all that apply): ___ Portable ___ Geophysical ___ Sonar ___ Other: __________
    • Flood monitoring required: ___ Yes ___ No
    • Flood monitoring event defined by (check all that apply):
      • ___ Discharge: __________
      • ___ Stage: __________
      • ___ Elev. measured from: __________
      • ___ Rainfall: ___ (in / mm) per ___ (hour)
      • ___ Flood forecasting information: __________
      • ___ Flood warning system: __________
    • Frequency of flood monitoring: ___ 1 Hr ___ 3 Hrs ___ 6 Hrs ___ Other: __________
    • Post-flood monitoring required: ___ No ___ Yes, within ___ days
    • Frequency of post-flood monitoring: ___ Daily ___ Weekly ___ Monthly ___ Other: __________
    • Criteria for termination of flood monitoring: ____________________
    • Criteria for termination of post-flood monitoring: ____________________
    • Scour alert elevation(s) for each pier/abutment: ____________________
    • Scour critical elevation(s) for each pier/abutment: ____________________

Note: Additional details for action(s) required may be included in Section 8.

Action(s) required if scour alert elevation detected (include notification and closure procedures): 
Action(s) required if scour critical elevation detected (include notification and closure procedures): 
Agency and department responsible for monitoring: 
Contact person (include name, title, telephone, pager, e-mail): 
7. COUNTERMEASURE RECOMMENDATIONS
Prioritize alternatives below. Include information on any hydraulic, structural or monitoring countermeasures.
___ Only monitoring required (see Section 6 and Section 10 - Attachment F):Estimated cost $ ____
___ Scour countermeasures considered (see Section 10, Attachment F):Priority RankingEstimated cost
(1)$
(2)$
(3)$
(4)$
(5)$
Basis for the selection of the preferred scour countermeasure: 
Countermeasure implementation project type:___ Proposed Construction Project
___ Maintenance Project
___ Programmed Construction - Project Lead Agency: ____________________
___ Bridge Bureau
___ Road Design
___ Other: ____________________
Agency and department responsible for countermeasure program (if different from Section 6 contact for monitoring): 
Contact person (include name, title, telephone, pager, e-mail): 
Target design completion date: 
Target construction completion date: 
Countermeasures already completed: 
8. BRIDGE CLOSURE PLAN
Scour monitoring criteria for consideration of bridge closure:___ Water surface elevation reaches ___ at ___
___ Overtopping road or structure
___ Scour measurement results / Monitoring device (See Section 6)
___ Observed structure movement / Settlement
___ Discharge: ___ cfs/cms
___ Flood forecast: ___
___ Other:
  • ___ Debris accumulation
  • ___ Movement of riprap/other armor protection
  • ___ Loss of road embankment
Emergency repair plans (include source(s), contact(s), cost, installation directions): 
Agency and department responsible for closure: 
Contact persons (name, title, agency/organization, telephone, pager, email): 
Criteria for re-opening the bridge: 
Agency and person responsible for re-opening the bridge after inspection: 
9. DETOUR ROUTE
Detour route description (route number, from/to, distance from bridge, etc.) - Include map in Section 10, Attachment E.: 
Bridges on Detour Route:
Bridge NumberWaterwaySufficiency Rating / Load LimitationsItem 113 Code
    
    
    
    
Traffic control equipment (detour signing and barriers) and location(s): 
Additional considerations or critical issues (susceptibility to overtopping, limited waterway adequacy, lane restrictions, etc.): 
News release, other public notice (include authorized person(s), information to be provided and limitations): 
10. ATTACHMENTS

Please indicate which materials are being submitted with this POA:

  • ___ Attachment A: Boring logs and/or other subsurface information
  • ___ Attachment B: Cross sections from current and previous inspection reports
  • ___ Attachment C: Bridge elevation showing existing streambed, foundation depth(s) and observed and/or calculated scour depths
  • ___ Attachment D: Plan view showing location of scour holes, debris, etc.
  • ___ Attachment E: Map showing detour route(s)
  • ___ Attachment F: Supporting documentation, calculations, estimates and conceptual designs for scour countermeasures.
  • ___ Attachment G: Photos
  • ___ Attachment H: Other information: ________________________________________

INSTRUCTIONS FOR COMPLETING THE PLAN OF ACTION

The existing bridge management system in your state will provide much of the information required to fill out this template. Note that all blocks in this template will expand automatically to allow as much space as you require. All fields can be modified to accommodate local terminology, as desired. Where check boxes are provided, they can be checked by double-clicking on the box and selecting the "checked" option. If you include additional attachments, please indicate this in Section 10.

Section 1

Foundations - It is recommended that substructure depths be shown in the bridge elevation, Attachment C (see Section 10). The minimum depth should be reported in Section 1 as a worst-case condition.

Subsurface soil information - If conditions vary with depth and/or between substructure units, this should be noted and included in Attachments A and/or C (see Section 10).

Sections 1, 2, 3 and 4

These sections are intended as an executive summary for the reviewer/manager who may not need the details of Sections 5 through 10, and show:

  • Section 1: General information
  • Section 2: Who prepared the POA
  • Section 3: The source of the problem
  • Section 4: What actions are recommended and their status

Section 3

Reasons why the bridge has been rated scour critical for Item 113:

Scour Critical

  • Aggressive stream or tidal waterway (high velocity, steep slope, deep flow)
  • Actively degrading channel
  • Bed material is easily eroded
  • Large angle of attack (> 10°)
  • Significant overbank or floodplain flow (floodplain >50 m or 150 ft wide)
  • Possibility of bridge overtopping (potential for pressure flow through bridge)
  • Evidence of scour and/or degradation
  • Evidence of structural damage due to scour
  • Foundations are spread footings on erodible soil, shallow piles, or embedment unknown
  • Exposed footing in erodible material
  • Exposed piles with unknown or insufficient embedment
  • Loss of abutment and/or pier protection
  • No countermeasures or countermeasures in poor condition
  • Needs countermeasures immediately

Unknown Foundations

  • No record of foundation type (spread footing vs. piles)
  • Depth of foundation or pile embedment unknown
  • Condition of foundation or pile embedment unknown
  • Subsurface soil strata not documented

Section 5

This section highlights recent changes in the scour/hydraulics coding items as an indication of potential problems or adverse trends. See FHWA Policy Memorandum on Revision of Coding Guide, Item 113 - Scour Critical Bridges dated April 27, 2001 for details on Items 113 and 60. A link to this memorandum is provided below:

http://www.fhwa.dot.gov/engineering/hydraulics/policymemo/revguide.cfm

Section 6

Multiple individuals responsible for various monitoring activities may be listed, as appropriate.

Section 7

Guidance on the selection and design of scour countermeasures may be found in FHWA Hydraulic Engineering Circular No. 23, Bridge Scour and Stream Instability Countermeasures, Second Edition, 2001. To facilitate the selection of alternative scour countermeasures, a matrix describing the various countermeasures and their attributes is presented in this circular. A link to this document is provided below:

http://isddc.dot.gov/OLPFiles/FHWA/010592.pdf

Section 8

Standard closure and reopening procedures, if available, may be appended to the POA (see Section 10, Attachment H).

Section 9

In some situations, public transportation (e.g., bus routes) may be of importance to the public, and therefore could be included in the POA (see Section 10, Attachment H).

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Updated: 04/07/2011
 

FHWA
United States Department of Transportation - Federal Highway Administration