· web view“underwater inspection of bridges”, report no. fhwa-dp-80-1. november 1989. the web...

WO AMENDMENT 7709.56b-2014-1EFFECTIVE DATE: 11/24/2014DURATION: This amendment is effective until superseded or removed.

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FSH 7709.56b - TRANSPORTATION STRUCTURES HANDBOOKCHAPTER 90 - ROAD BRIDGE OPERATION

Table of Contents

90.6 - References.........................................................................................................................291 - INSPECTIONS..........................................................................................................4

91.1 - General Requirements.......................................................................................................491.2 - Inspection Intervals...........................................................................................................491.3 - Fracture Critical Inspections.............................................................................................591.4 - Scour Evaluation...............................................................................................................591.5 - Historic Bridge Evaluation and Inventory........................................................................591.6 - Culvert Inspections............................................................................................................5

92 - BRIDGE MANAGEMENT.........................................................................................892.1 - Load Ratings...................................................................................................................1192.2 - Bridge Overload Permits.................................................................................................1192.3 - Weight Limit Posting, Closing, and Signing...................................................................1292.4 - Permanent Bridge File.....................................................................................................1392.5 - Object Markers................................................................................................................1492.6 - Substandard Railing on Existing Road Bridges..............................................................14

93 - PRIVATELY OWNED ROAD BRIDGES................................................................1493.1 - Inspection, Posting, and Signing.....................................................................................1593.2 - Maintenance, Repair or Replacement.............................................................................16


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90.6 - References

1. American Association of State Highway and Transportation Officials (AASHTO). “The Manual for Bridge Evaluation”. Current edition. The web address to order these publications is: https://bookstore.transportation.org/browse_bookstore.aspx

2. AASHTO. “AASHTO, Guide Specification for Strength Evaluation of Existing Steel and Concrete Bridges.” The web address to order this publication: https://bookstore.transportation.org/browse_bookstore.aspx

3. AASHTO. “AASHTO LRFD Bridge Design Specifications”. Current Edition. The web address to order this publication is: https://bookstore.transportation.org/browse_bookstore.aspx

4. U.S. Department of Agriculture, Forest Service (USDA - FS). “Sign and Poster Guidelines for the Forest Service”, EM-7100-15. Current Edition. http://www.fs.fed.us/eng/techdev/sdtdc.htm

5. USDA - FS. “Identifying and Preserving Historic Bridges”, 7100 Engineering, December 2000, Publication No. 0071-2854-MTDC. The web address to order this publication is: http://www.fs.fed.us/eng/php/eng_search.php?category=Program&srchword=05

6. USDA - FS. Bridge Scour Evaluation: Screening, Analysis, and Countermeasures. 7700 - Transportation Systems, September 1998, Publication No. 9877 1207-SDTDC. http://www.fs.fed.us/eng/techdev/sdtdc.htm

7. USDA - FS, “Timber Bridges, Design, Construction, Inspection and Maintenance”. EM-7100-8. August 1992. The web address to order this publication is: http://www.fpl.fs.fed.us/products/publications/

8. U.S. Department of Transportation, Federal Highway Administration (FHWA). “Culvert Inspection Manual, Supplement to the Bridge Inspector's Reference Manual”, Report No. FHWA NHI 03-001. October 2002. The web address to order this publication is: http://www.fhwa.dot.gov/bridge/elibrary.htm

9. U.S. Department of Transportation, FHWA. “Inspection of Fracture Critical Bridge Members, Supplement to the Bridge Inspector's Reference Manual”, Report No. FHWA NHI 03-001, October 2002. The web address to order this publication is: http://www.fhwa.dot.gov/bridge/elibrary.htm

http://www.fhwa.dot.gov/bridge/elibrary.htm


http://www.fpl.fs.fed.us/products/publications/

http://www.fs.fed.us/eng/techdev/sdtdc.htm

http://www.fs.fed.us/eng/php/eng_search.php?category=Program&srchword=05

http://www.fs.fed.us/eng/php/eng_search.php?category=Program&srchword=05

http://www.fs.fed.us/eng/techdev/sdtdc.htm

https://bookstore.transportation.org/browse_bookstore.aspx




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10. U.S. Department of Transportation. FHWA. “Manual on Uniform Traffic Control Devices” (MUTCD). Current Edition. The web address to order this publication is: http://mutcd.fhwa.dot.gov/ser-pubs.htm

11. U.S. Department of Transportation, FHWA. “Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation’s Bridges,” Report No. FHWA-PD-96-001. Current Edition. The web address to order this publication is: http://www.fhwa.dot.gov/bridge/elibrary.htm

12. U.S. Department of Transportation, FHWA. “Underwater Inspection of Bridges”, Report No. FHWA-DP-80-1. November 1989. The web address to order this publication is: http://www.fhwa.dot.gov/bridge/elibrary.htm

13. U.S. Department of Transportation, FHWA. HIF-12-003. April, 2015. Hydraulic Engineering Circular No. 18, “Evaluating Scour at Bridges”, 5th Edition. The web address to order this publication is: http://www.fhwa.dot.gov/bridge/elibrary.htm

14. U.S. Department of Transportation, FHWA. HIF-12-004. 2012. Hydraulic Engineering Circular No. 20. “Stream Stability at Highway Structures”, 4th Edition. The web address to order this publication is: http://www.fhwa.dot.gov/bridge/elibrary.htm

15. U.S. Department of Transportation, FHWA. NHI-09-111 and NHI-09-112. Hydraulic Engineering Circular No. 23. “Bridge Scour and Stream Instability Countermeasures Experience, Selection and Design Guidance, Volumes I and II”. The web address to order this publication is: http://www.fhwa.dot.gov/bridge/elibrary.htm

16. U.S. Department of Transportation, FHWA, ‘Bridge Inspector's Reference Manual” (BIRM). The web address to order this publication is: http://www.fhwa.dot.gov/bridge/elibrary.htm

17. U.S. Department of Transportation, FHWA. IP-04-016. October 2005. Hydraulic Engineering Circular No. 9, Debris Control Structures Evaluation and Countermeasures, 3rd Edition. The web address to order this publication is: http://www.fhwa.dot.gov/bridge/elibrary.htm

18. Title 23, CFR 650, Subpart C. National Bridge Inspection Standards (NBIS). Electronic Code of Federal Regulations. The web address to view this publication is: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=acfc0821687127660521bcdf66badd4c&rgn=div5&view=text&node=23:1.0.1.7.28&idno=23#23:1.0.1.7.28.3

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=acfc0821687127660521bcdf66badd4c&rgn=div5&view=text&node=23:1.0.1.7.28&idno=23#23:1.0.1.7.28.3










http://mutcd.fhwa.dot.gov/ser-pubs.htm


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19. Title 23, CRF 658.18, Truck Size and Weight, Route Designations - Length, Width and Weight Limitations - Weight. Electronic Code of Federal Regulations. The web address to view this publication is: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr;sid=78f213fb3cf4c5130b704f541c8569cd;rgn=div5;view=text;node=23%3A1.0.1.7.33;idno=23;cc=ecfr

91 - INSPECTIONS

91.1 - General Requirements

Use the National Bridge Inspection Standards (NBIS) (23 CFR Part 650, Subpart C) to guide all inspections of bridges on National Forest System (NFS) roads.

The following applies to inspection of all bridges on NFS roads:

1. Inspect bridges in accordance with the NBIS and AASHTO’s Manual for Bridge Evaluation.

2. Identify bridges with fracture critical members, bridges requiring underwater inspection, and bridges that are scour critical.

3. Load rate bridges for safe load carrying capacity (sec. 92.1).

4. Prepare and maintain road bridge inspection reports, records, and inventory data in the permanent bridge file (sec. 92.4).

5. Ensure that all data required by FHWA and national Forest Service directives are current and properly entered in the Infrastructure database (Infra).

91.2 - Inspection Intervals

All bridges on NFS roads must receive routine inspections per the NBIS. In accordance with NBIS, the interval between routine inspections must be no more than 24 months.

The Washington Office, Director of Engineering, with FHWA concurrence, may approve extended inspection intervals of up to 48 months. Requests to extend inspection intervals must be specific to each bridge, include supporting data justifying the extension, be submitted in writing, and be endorsed in writing by the Regional Director of Engineering (FSM 7736.04).

The Forest Service’s policy for varying the frequency of routine inspections from the 24 month requirement to a maximum of 48 months on selected bridges is based on the general guidelines contained in Federal Highway Administration (FHWA) Technical Advisory, Revisions to the National Bridge Inspection Standards (NBIS), TA 5140.21. The Forest Service’s assessment is that the bridges selected for an increase in routine inspection interval from the typical 24 month

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr;sid=78f213fb3cf4c5130b704f541c8569cd;rgn=div5;view=text;node=23%3A1.0.1.7.33;idno=23;cc=ecfr




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inspection frequency, are in fair to very good condition, shall adhere to the guidance in FHWA Technical Advisory 5140.21. A supplement with specific criteria shall be issued from Washington Office Director of Engineering at which time Regions and Forests will be able to submit bridges for approval to extend the inspection interval.

91.3 - Fracture Critical Inspections

The Bridge Inspection Program Manager shall identify bridges with fracture critical members (FCMs) in conformance with section 650.313 of the NBIS; identify the location of FCMs; document the required FCM inspection frequency and procedures in the permanent bridge file; inspect FCMs according to these procedures; and document inspections in the permanent bridge file.

91.4 - Scour Evaluation

Evaluate and inventory bridges for scour susceptibility per USDA-Forest Service’s Bridge Scour Evaluation: Screening, Analysis, and Countermeasures.

Prepare an action plan for bridges that are identified as scour critical to monitor known and potential deficiencies and to address critical findings. Monitor bridges that are scour critical in accordance with the action plan.

91.5 - Historic Bridge Evaluation and Inventory

Record Historic Register status of bridges as outlined in USDA, Forest Service publication “Identifying and Preserving Historic Bridges” and in updated I-Web coding direction.

91.6 - Culvert Inspections

Culverts with a clear span of up to 20 feet measured along the centerline of the road are considered to be part of the roadway. Inspect these culverts as part of the road condition survey.

Culverts with a clear span of more than 20 feet measured along the centerline of the road should be inspected by a Bridge Inspection Team Leader in accordance with the NBIS. These culverts are referred to as culvert reported as bridges (CRABs) by the Forest Service. Enter and maintain inventory and NBIS data in the Culvert database of the Infra Roads Module.

Any bottomless (natural channel) structure with footings that has wheel loads in direct contact with the top of the structure is considered to be a bridge, regardless of span. Inspect, maintain, manage, and inventory these structures as road bridges.

The Forest Supervisor, in consultation with the Bridge Inspection Program Manager, may require any culvert with a clear span of up to 20 feet to be inspected, managed, and inventoried to the same requirements as a culvert with a clear span of more than 20 feet when the culvert and site conditions warrant greater scrutiny.


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Any multiple-opening installation consisting of culverts with clear spans totaling more than 20 feet has the same inspection and inventory requirements as a single culvert with a clear span of more than 20 feet. For more detail on this topic, see Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation’s Bridges, Item 112, NBIS Bridge Length.

Refer to Exhibit 01 for additional information.


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91.6 – Exhibit 01

Classification and Requirements for the Inspection and Inventory of Forest Service Culverts and Bridges

Any Single-Opening Structure With a Bottom, Regardless of Fill Depth or Depth of Invert Burial

Any Single-Opening, Bottomless (Natural Channel) Structure With Footings That Will Not Have Wheel Loads in Direct Contact With the Top of the Structure

Any Single- or Multiple-Opening, Bottomless (Natural Channel) Structure With Footings That Has Wheel Loads in Direct Contact With the Top of the Structure

Clear Span (CS)1 CS ≤ 20 feet CS > 20 feet CS ≤ 20 feet CS > 20 feet All SpansInspection3 Classification Culvert CRAB2 Culvert CRAB2 Bridge

Responsibility Part of the roadway complete as part of road condition survey.

Bridge inspection team leader, in accordance with the NBIS.

Part of roadway; complete as part of road condition survey.



Inventory Classification Culvert only. Culvert installation and culvert records.

Culvert only. Culvert installation and culvert records

Bridge

Responsibility Only culvert data, by Infra travel routes data manager.

Upon installation, enter and maintain inventory and NBIS data in culvert database of Infra Roads Module.

Only culvert data, by Infra travel routes data manager.

Upon installation, enter and maintain inventory and NBIS data in Culvert Database ofInfra Roads Module.

Enter and maintain all NBIS bridge and real property data in Infra Bridge Module for financial accountability and data reporting.

1 Defined as NBIS opening for a single- or multiple-opening structure.2 A culvert reported as a bridge in accordance with the NBIS.3 The Forest Supervisor can require a culvert with a clear span of up to 20 feet to be inspected as a CRAB.


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92 - BRIDGE MANAGEMENT

Except for roads where off-highway haul has been permitted (FSM 7731.18), legal vehicle loads on NFS roads are addressed in the Federal Bridge Gross Weight Formula (Bridge Formula) (23 CFR Part 658.17). (Refer to exhibit 01). The maximum gross vehicle weight is based on the number of axles and the axle spacing. The maximum allowable gross vehicle weight is 80,000 pounds, except where axle weight limitations dictated by the Bridge Formula result in a lower gross vehicle weight. The posted load limits for a bridge may be lower than the maximum allowable gross vehicle weight.

Federal Bridge Gross Weight Formula

W = 500 [(LN/(N-1)) + 12N + 36]

W = the gross weight on any group of two or more consecutive axles to the nearest 500 pounds,

L = the distance in feet between the furthest points of any group of two or more consecutive axles, and

N = the number of axles in the group under consideration

Overload permits are required for any vehicle which exceeds the maximum allowable gross vehicle weight of 80,000 pounds; if single axle loads exceed 20,000 pounds or tandem axle loads exceed 34,000 pounds; or if the vehicle exceeds the posted load limits for the bridge.

Existing railroad car bridges should be weight-restricted and signed as appropriate. Schedule railroad car bridges for removal or replacement as funds become available.


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92 - Exhibit 01Bridge Formula Table

Distance in Feet Between Extremes of Any Group of 2

or More Consecutive Axles

Maximum Load in Pounds on Any Group of 2 or More Consecutive Axles1

2 Axles 3 Axles 4 Axles 5 Axles 6 Axles 7 Axles 8 Axles 9 Axles

4 34,0003

5 34,0003

6 34,0003

7 34,0003

Up to 8 34,0003 34,000More Than 8 38,000 42,000

9 39,000 42,50010 40,000 43,50011 44,00012 45,000 50,00013 45,000 50,50014 46,500 51,50015 47,000 52,00016 48,000 52,500 58,00017 48,500 53,500 58,50018 49,500 54,000 59,00019 50,500 54,500 60,00020 51,000 55,500 60,500 66,00021 51,500 56,000 61,000 66,50022 52,500 56,500 61,500 67,00023 53,000 57,500 62,500 68,00024 54,000 58,000 63,000 68,500 74,00025 54,500 58,500 63,500 69,000 74,50026 55,500 59,500 64,000 69,500 75,00027 56,000 60,000 65,000 70,000 75,50028 57,000 60,500 65,500 71,000 76,500 82,00029 57,500 61,500 66,000 71,500 77,000 82,50030 58,500 62,000 66,500 72,000 77,500 83,00031 59,000 62,500 67,500 72,500 78,000 83,50032 60,000 63,500 68,000 73,000 78,500 84,500 90,00033 64,000 68,500 74,000 79,000 85,000 90,50034 64,500 69,000 74,500 80,000 85,500 91,00035 65,500 70,000 75,000 80,500 86,000 91,50036 66,000 70,500 75,500 81,000 86,500 92,00037 66,500 71,000 76,000 81,500 87,000 93,00038 67,500 71,500 77,000 82,000 87,500 93,50039 68,000 72,500 77,500 82,500 88,500 94,00040 68,500 73,000 78,000 83,500 89,000 94,500


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92 - Exhibit 01-Continued

41 69,500 73,500 78,500 84,000 89,500 95,00042 70,000 74,000 79,000 84,500 90,000 95,50043 70,500 75,000 80,000 85,000 90,500 96,00044 71,500 75,500 80,500 85,500 91,000 96,50045 72,000 76,000 81,000 86,000 91,500 97,50046 72,500 76,500 81,500 87,000 92,500 98,00047 73,500 77,500 82,000 87,500 93,000 98,50048 74,000 78,000 83,000 88,000 93,500 99,00049 74,500 78,500 83,500 88,500 94,000 99,50050 75,500 79,000 84,000 89,000 94,500 100,00051 76,000 80,000 84,500 89,500 95,000 100,50052 76,500 80,5002 85,000 90,500 95,500 101,00053 77,500 81,000 86,000 91,000 96,500 102,00054 78,000 81,500 86,500 91,500 97,000 102,50055 78,500 82,500 87,000 92,000 97,500 103,00056 79,500 83,000 87,500 92,500 98,000 103,50057 80,000 83,500 88,000 93,000 98,500 104,00058 84,000 89,000 94,000 99,000 104,50059 85,000 89,500 94,500 99,500 105,00060 85,500 90,000 95,000 100,500 105,500

1. Permissible loads are computed to the nearest 500 pounds.2. Weights shown in red exceed the Forest Service gross vehicle weight.3. Tandem axle by definition.


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92.1 - Load Ratings

A Bridge Loading Rating Engineer shall complete a load rating for all Forest Service road bridges on NFS lands. Perform load ratings in conformance with chapter 6 of AASHTO’s Manual for Bridge Evaluation for the design load, the AASHTO Type 3, Type 3S2, and Type 3-3 vehicles, and Specialized Hauling Vehicles (SHVs). The AASHTO Type 3, 3S2 and 3-3 and SHVs comply with the Bridge Formula, are representative of current average truck configurations, and are used as models for load ratings by most public road authorities.

Load rate road bridges regardless of construction material using the load and resistance factor rating (LRFR) method and the HL-93 design load. Existing load ratings that were completed using other methodologies, do not need to be redone using LRFR unless a new load rating is required due to changed conditions. See FSH 7709.56b, section 92.3, for safe load carrying capacity determinations based on other methods.

92.2 - Bridge Overload Permits

The Forest Supervisor, with the concurrence of the Bridge Inspection Program Manager, is responsible for issuing overload permits for any non-reducible load that exceeds 80,000 pounds or a lower maximum allowable gross vehicle weight dictated by the Bridge Formula. Item 5 below discusses reducible loads.

When load rating analysis is required, it must be conducted by a Certified Load Rating Engineer. Issue bridge overload permits as follows:

1. Issue a bridge overload permit to authorize occasional use of a bridge by a vehicle that exceeds the maximum allowable gross vehicle weight established by the Bridge Formula, up to the safe load carrying capacity of the bridge as determined by the load rating for that vehicle (FSM 7731.1 and 7736.41). Issue a bridge overload permit for a single trip or for a specific number of trips for the analyzed load size.

2. Monitor bridge overload permits to ensure that the size and number of the loads do not exceed the requirements of the permit.

3. See FSM 7731.17 for general direction on road use permits and FSM 7731.18 for direction on off-highway haul.

4. Issue bridge overload permits separately from other road use permits (see forms FS-7700-40, Application for Road Use Permit, and FS-7700-48, Road Use Permit). While the FS-7700-40 is always required, National or Regional standard Forest Service


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forms or forms developed by State Departments of Transportation may be used for permits. The overload permit must describe the features of the vehicle and its load and must specify the allowable travel route. Overload permits must be issued in accordance with FSM 7736.42.

5. When practical, haulers should be required to reduce or eliminate overloads. In most cases, an overload permit should not be issued when the load or the hauling vehicle can be reduced to conform to applicable size and weight limitations or local regulations. Timber sale contracts should limit loads to the maximum allowable gross vehicle weight dictated by the Bridge Formula.

6. Keep a copy of bridge overload permits in the permanent bridge file.

92.3 - Weight Limit Posting, Closing, and Signing

The Forest Supervisor, in consultation with the Bridge Inspection Program Manager, is responsible for posting or closing road bridges when a load rating for any of the three types of AASHTO standard vehicles (Type 3, 3S2 and 3-3) yields a safe load carrying capacity that is less than the gross vehicle weight of those vehicles as dictated by the Bridge Formula.

A load rating using LRFR yields a single rating factor. Use this rating factor with the gross vehicle weights of the rating vehicles to determine the safe load carrying capacity, in conformance with chapter 6A.8.3, Posting Analysis of AASHTO’s Manual for Bridge Evaluation. Road bridges determined to have a rating factor of less than 1.00 for any of the three types of AASHTO vehicles must be posted with their safe load carrying capacity.

A load rating using a method other than LRFR (such as the allowable stress or load factor methods) yields inventory and operating ratings. Road bridges with a load rating performed with a method other than LRFR that have an operating rating ratio of less than 1.00 for any of the three types of AASHTO vehicles must be posted with their safe load carrying capacity in accordance with chapter 6B.7 of AASHTO’s Manual for Bridge Evaluation.

Consider re-rating bridges with a load rating performed with a method other than LRFR that have an operating rating ratio of less than 1.00 for any of the three types of AASHTO vehicles using LRFR and, if necessary, post according to LRFR with their safe load carrying capacity. Regional guidance may require stricter requirements for posting safe load carrying capacity.

Post weight restrictions at bridges using an R12-1, R12-2, or R12-5 sign (EM-7100-15 and the MUTCD). Posting using the single load limit R12-1 sign may be overly restrictive for longer vehicle loads.


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The maximum allowable gross vehicle weight for the three types of AASHTO vehicles is:

Type 3 Truck: 25 tonsType 3S2 Truck: 36 tonsType 3-3 Truck: 40 tons

Bridges not capable of carrying a minimum allowable gross vehicle weight of 3 tons (6,000 pounds) must be closed. Bridges must be closed when the bridge is determined to be unsafe for other reasons other than loading by the Bridge Inspection Program Manager. Because signs and barricades can be vandalized or stolen, physically block the bridges to all traffic with barriers that can only be moved by heavy construction equipment. A bridge must be posted accordingly as soon as possible, not to exceed 30 days or the earliest possible time if road is closed due to winter conditions, after a load rating determines a bridge requires a weight restriction.

92.4 - Permanent Bridge File

Maintain a permanent bridge file for each NFS road bridge per AASHTO’s Manual for Bridge Evaluation. Maintain this file at a single location determined by regional guidance (FSH 7709.56b, sec. 91.1, para. 4). The permanent bridge file should be readily available to the Bridge Inspection Program Manager and at a minimum should include:

1. As-built plans;

2. Design calculations, including preliminary design reports, hydrological and hydraulic reports and geotechnical and foundation investigation reports;

3. Inspection reports, including summaries and photographs;

4. Load rating calculations;

5. A record of issued overload permits, maintenance, repairs, and modifications; and

6. Design information per FSM 7722.1(.7).

7. QA/QC documentation.

8. Critical findings and actions taken; Plan of Action (POA) may be created to monitor.

9. Plan of Action (POA) for scour critical bridges and those with unknown foundation.

10. Posting documentation.

11. Significant correspondence.


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92.5 - Object Markers

Delineate all four corners of a road bridge that has a TL 1 curb traffic barrier with properly located Type III object markers. Type III object markers must be installed in compliance with the current edition of the Manual on Uniform Traffic Control Devices (MUTCD).

Install MUTCD compliant object markers at bridges with approach guardrail when geometric and traffic conditions make the ends of the guardrail difficult to see or the ends of the guardrail are very near the roadway. Position object markers to delineate the feature determined to present the greatest hazard to motorists.

92.6 - Substandard Railing on Existing Road Bridges

Identify bridges that have bridge traffic barrier systems or approach guardrail systems that do not meet the design standards in FSM 7722.12 and section 72.3 of this Handbook. If based on an analysis, it is determined that the risk associated with these bridges is sufficient to warrant replacement or modification of the bridge traffic barrier or approach guardrail, use appropriate signing, such as a narrow bridge sign or object markers, per EM-7100-15 and the MUTCD, and employ appropriate management measures such as inspection and traffic control until the bridge traffic barrier or approach guardrail is replaced or modified. If the analysis indicates the risk is too low to warrant replacement or modification, retain the analysis in the permanent bridge file. Update the analysis as needed to evaluate changes in use patterns, traffic speeds, or volume that may change the degree of risk associated with the bridge.

Existing bridges with a guardrail that does not meet current design standards should be evaluated for the appropriate Test Level traffic barrier in accordance with FSM 7722.12 and section 72.3 of this Handbook. If the evaluation indicates that a TL 1 curb is warranted, the guardrail maybe removed and replaced with a TL 1 curb.

Consider interim measures other than installation of an approach guardrail, such as additional signage or delineation, installation of short sections of approach guardrail or earthen berms, or use of bridge guardrail end treatments, for bridges with a substandard guardrail that are scheduled to be removed during maintenance or rehabilitation.

93 - PRIVATELY OWNED ROAD BRIDGES

Special-use authorizations for privately owned road bridges on NFS lands authorized by permit, term permit, lease, or easement (special-use authorizations) should include clauses for inspection, operation, and maintenance of these bridges to adequately protect the public and National Forest System Lands and resources. The inspection, operation, and maintenance requirements within FSM 7736 and the guidance of this section are recommended for all road bridges designed and installed on NFS roads or NFS lands, regardless of bridge ownership or road jurisdiction.


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Permit holders are responsible for compliance with the requirements and inspection, operation, and maintenance costs for road bridges authorized by their permit.

The following technical advice is recommended for road bridges on roads authorized by a special use permit on NFS Lands.

93.1 - Inspection, Posting, and Signing

Ensure that all bridges authorized by a special use permit meet NBIS requirements (23 CFR Part 650). In particular, ensure that:

1. Routine inspections are completed by an individual who meets NBIS qualifications for Inspection Team Leaders and are conducted in accordance with AASHTO’s Manual for Bridge Evaluation;

2. A damage inspection is completed by an individual who meets NBIS qualifications for Inspection Team Leaders following an event that has damaged or potentially damaged the bridge. Ensure that the permit holder reports the results of the inspection as soon as practicable to the Forest Service;

3. The bridges have a load rating performed by a professional Engineer registered in the State where the bridge is located that establishes the safe load carrying capacity of the bridge in accordance with AASHTO’S Manual for Bridge Evaluation. See FSH 7709.56b, section 92.3, for the maximum allowable gross vehicle weight for the three types of AASHTO vehicles. If the load rating of a bridge is less than the maximum allowable gross vehicle weight as, ensure that the holder posts the load rating for the bridge in accordance with AASHTO’s Manual for Bridge Evaluation and the MUTCD. If the bridge has a load rating of less than 3 tons, ensure that the holder closes the bridge to motor vehicle traffic using MUTCD-compliant barricades posted with “Road Closed” signs; and

4. The holder maintains a bridge inspection file that is available to the Forest Service upon request and that at a minimum includes:

a. A current inspection report.

b. Load rating calculations.

c. Bridge design calculations and plans, if available.

d. Photographs of the bridge, approaches, elevations, the channel upstream and downstream, and any visible deficiencies in the bridge structure.


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93.2 - Maintenance, Repair or Replacement

Ensure that the holder provides a copy of plans for routine maintenance and any proposed repairs or replacement to the authorized officer for review prior to commencing the work. Ensure that the operating plan addresses how and when maintenance, repairs, and replacement will be conducted. Ensure that the operating plan allows the Authorized Officer to require the holder to develop a design, plans, and specifications for this work and abide by construction standards established by the Bridge Engineer per FSH 7709.56b, section 79.2.

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