1. TRAIL BRIDGE INSPECTION 101

2. Mission Statement
This PowerPoint is intended to familiarize the budding inspector with bridge terminology and concepts so they are ready and able to participate in a more in-depth discussions during the classroom sessions.

3. Trail Bridges 101 Why do we inspect trail bridges?
Who can inspect trail bridges?
What is a trail bridge?
What does that bridge term mean?
What are checks, splits, etc?
What tools do I need for inspection?
What should I wear for safety?

4. Why do we inspect trail bridges?
Safety!!
National Bridge Inspection Standards
It’s just water over the bridge…☺

5. Bridge Inspection History
During the bridge construction boom of the 1950’s and 1960’s, little emphasis was placed on safety inspection and maintenance of bridges. This changed when the 2,235 foot Silver Bridge at Point Pleasant, WV, collapsed into the Ohio River, on Dec. 15, people were killed.

6. Bridge Inspection History
The Federal Highway Act of 1968 required the Secretary of Transportation to establish a national bridge inspection standard and develop a program to train bridge inspectors.
National Bridge Inspection Standards were developed for Road Bridges.

7. Forest Service Trail Bridge Inspector Qualifications
FSM Qualifications of Personnel Responsible for Trail Bridges Inspection and Condition Assessment
Qualification and certification requirements shall be established by Regional guidance (FSH b, sec. 05).
Routine Inspection of Trail Bridges
1. Inspection of Complex Trail Bridges. Complex trail bridges, viewing platforms, and other complex trail structures whose failure would be likely to put the public at risk, generally exceeding a 20-foot length and a 5-foot height (distance from the ground or stream channel to the top of the deck of the bridge), and all bridges which require a higher level of inspection due to decay, hazard, damage, or design complexity shall be inspected using the same inspection procedures as in a, except as follows:
a. Rate trail bridges for load carrying capacity in accordance with Regional guidance.
b. Coding Guide data is not submitted to Federal Highway Administration (FHWA).
c. Application of the requirements to list bridges requiring special inspections must be in accordance with Regional guidance (23 CFR , para. e).
2. Routine Inspection of Major Trail Bridges. Major trail bridges, whose failure would likely put the public at risk, generally timber bridges exceeding a length of 20 feet and a height of 5 feet, shall be inspected using Regional guidance.
3. Condition Assessment of Minor Trail Bridges. A condition assessment, in lieu of a routine inspection, in accordance with Regional guidance shall be performed on minor trail bridges that are small, that pose no significant risk to the public, or that are not sited in hazardous locations, and are less than 20 feet long or less than 5 feet high.
4. Routine Inspection Interval. Inspection intervals for trail bridges must not exceed 5 years.
Qualifications of Personnel
Qualifications of Personnel Responsible for Trail Bridges Inspection and Condition Assessment
Qualification and certification requirements shall be established by Regional guidance (FSH b, sec. 05).
Certifying and Verifying Qualified Personnel
Follow these procedures for certifying and verifying the qualifications of bridge inspection program managers and bridge inspection team leaders (FSM ):
1. Use a letter of certification, signed by the Regional staff director for engineering activities, to document certification or re-certification. Both initial certification and re-certification are valid for 4 years.
2. Recertify those individuals who have performed bridge inspection program assignments in a responsible capacity (23 CFR (a) and (b)), as verified and validated by the Forest staff officer for engineering activities or by an appropriate member of the Regional Office staff responsible for engineering activities.
3. Do not apply these certification requirements to members of bridge inspection teams. Training and skill requirements for members of bridge inspection teams must be in accordance with Regional guidance (FSH b, sec. 05).
8.1c - Inspection of Complex Trail Bridges
Inspections of complex trail bridges must meet the same requirements as road bridges subject to the NBIS except:
1. Coding Guide data is not submitted to FHWA.
2. If required, complex trail bridges should be load rated in accordance with Regional guidance.
3. Compiled list of bridges requiring special inspections shall be in accordance with Regional guidance.
4. A list of all complex trail bridges shall be maintained.
8.1d - Routine Inspection of Major Trail Bridges and Condition Assessments of Minor Trail Bridges
Major trail bridges must be inspected by major trail bridge inspectors certified in accordance with Regional guidance.
Condition assessments must be completed for minor trail bridges by minor trail bridge technicians, certified in accordance with Regional guidance.
Inspection Intervals
Routine inspection (sec. 8.05) intervals of road bridges must be in accordance with FSM and FSM and 8.1.
When Forests or Regions propose to inspect any NBIS road bridges (sec. 8.01) less frequently than the specified 2-year interval (up to 4 years maximum), a detailed proposal with supporting data justifying the increase in interval for each bridge must be submitted through the regional staff director for engineering activities, to the director of engineering, Washington Office, for approval (FSM a).
When Forests propose to inspect any non-NBIS road bridges less frequently than the specified 2-year interval (up to 4 years maximum), a detailed proposal with supporting data justifying the increase in interval for each bridge must be submitted to the regional staff director for engineering activities for approval (FSM b).
Use the following evaluation criteria to screen proposals to increase any bridge inspection intervals:
Criteria to extend routine bridge inspection intervals:
1. The bridge must not be fracture or scour critical.
2. The bridge must not be subject to excessive, frequent traffic damage.
3. The bridge must not require posting restrictions per section 8.33.
4. The bridge deck, superstructure, and substructure elements must have a condition code of 6 or higher, based on the FHWA “Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation’s Bridges” (sec. 8.08).
5. The bridge has had no significant repair or rehabilitation work within the last 2 years.
6. Overloads are on a permit-basis only and are recorded.
7. The bridge must not be subject to frequent or excessive overloads.
If any of these criteria develops during the extended inspection cycle, the inspection cycle shall revert to 2 years, or less as determined by the condition.
Inspection Procedures
Inspection procedures for road and trail bridges must be in accordance with FSM

8. What is a Trail Bridge? General Definition of a Trail Bridge from the
TRAIL BRIDGE MATRIX:
A trail structure, including supports, erected over a depression or obstruction such as water, roadway, trail, or railway that provides a continuous pathway and has a deck for carrying traffic or other loads.

9. Trail Bridge Matrix
Complex Trail Bridge. A trail bridge, viewing platform, or other trail structure, including a truss or a suspension, multi-span, or non-timber bridge, that exceeds 20 feet in length and 5 feet in height (as measured from the ground or stream channel to the top of the deck of the bridge, platform, or other structure); that requires a high level of expertise for routine inspections due to decay, hazards, damage, or design complexity; and whose failure likely would put the public at risk.
Major Trail Bridge. A timber bridge, viewing platform, or other trail structure, including a single-span timber bridge, that exceeds 20 feet in length and 5 feet in height (as measured from the ground or stream channel to the top of the deck of the bridge, platform, or other structure); that requires technical timber bridge expertise for routine inspections; and whose failure likely would put the public at risk.
Minor Trail Bridge. A trail bridge or other trail structure that is less than 20 feet long or less than 5 feet high (as measured from the ground or stream channel to the top of the deck of the bridge or other structure); that requires general condition assessment expertise for routine inspections; and whose failure poses no significant risk to the public.

10. Trail Bridge Matrix

11. Classification of Trail Bridges
TRAIL BRIDGE MATRIX:
Complex
Major
Minor
* Inspection interval for all trail bridge classifications is every 5 years
Complex Trail Bridge. A trail bridge, viewing platform, or other trail structure, including a truss or a suspension, multi-span, or non-timber bridge, that exceeds 20 feet in length and 5 feet in height (as measured from the ground or stream channel to the top of the deck of the bridge, platform, or other structure); that requires a high level of expertise for routine inspections due to decay, hazards, damage, or design complexity; and whose failure likely would put the public at risk.
Major Trail Bridge. A timber bridge, viewing platform, or other trail structure, including a single-span timber bridge, that exceeds 20 feet in length and 5 feet in height (as measured from the ground or stream channel to the top of the deck of the bridge, platform, or other structure); that requires technical timber bridge expertise for routine inspections; and whose failure likely would put the public at risk.
Minor Trail Bridge. A trail bridge or other trail structure that is less than 20 feet long or less than 5 feet high (as measured from the ground or stream channel to the top of the deck of the bridge or other structure); that requires general condition assessment expertise for routine inspections; and whose failure poses no significant risk to the public.

12. Complex Trail Bridge Whose failure likely would put the public at risk
Made of wood, concrete, fiberglass, steel, suspension, or trusses
Usually greater than 20 ft long &
Greater than 5 ft height
Single or multiple span
Any bridge that requires higher inspection skills
Requires a technical inspection by an engineer or engineering technician certified road bridge inspector
Complex Trail Bridge. A trail bridge, viewing platform, or other trail structure, including a truss or a suspension, multi-span, or non-timber bridge, that exceeds 20 feet in length and 5 feet in height (as measured from the ground or stream channel to the top of the deck of the bridge, platform, or other structure); that requires a high level of expertise for routine inspections due to decay, hazards, damage, or design complexity; and whose failure likely would put the public at risk.

13. Example: Steel Deck Truss
COMPLEX TRAIL BRIDGE
Example: Steel Deck Truss

14. COMPLEX TRAIL BRIDGE
Example: Fiberglass

15. Example: Steel Thru Truss
COMPLEX TRAIL BRIDGE
Example: Steel Thru Truss

16. Example: Old Railroad Trestle
COMPLEX TRAIL BRIDGE
Example: Old Railroad Trestle

17. COMPLEX TRAIL BRIDGE
Example: Suspension

18. COMPLEX TRAIL BRIDGE Other Examples of Complex Trail Bridges: Concrete
Masonry
Arches
Multi-Span Structures
Complex Designs

19. Major Trail Bridge Whose failure likely would put the public at risk
Made of wood (log/timber/glulam)
Greater than 20 ft long &
Greater than 5 ft height
Single span
Requires a technical inspection by a person:
1. Trained specifically for log and/or timber trail bridge inspections; and
2. Deemed qualified, based on Regional Guidance.
Major Trail Bridge. A timber bridge, viewing platform, or other trail structure, including a single-span timber bridge, that exceeds 20 feet in length and 5 feet in height (as measured from the ground or stream channel to the top of the deck of the bridge, platform, or other structure); that requires technical timber bridge expertise for routine inspections; and whose failure likely would put the public at risk.

20. MAJOR TRAIL BRIDGE
Wood and >20 ft long and >5 ft high and single span
Example: Treated Log Stringer

21. MAJOR TRAIL BRIDGE
Wood and >20 ft long and >5 ft high and single span
Example: Untreated Log Stringer

22. Wood and >20 ft long and >5 ft high and single span
MAJOR TRAIL BRIDGE
Wood and >20 ft long and >5 ft high and single span
Example: Glulam Beam

23. Wood and >20 ft long and >5 ft high and single span
MAJOR TRAIL BRIDGE
Wood and >20 ft long and >5 ft high and single span
Example: Sawn Lumber

24. Minor Trail Bridge
Whose failure poses no significant risk to the public
Made of wood (log/timber/glulam)
Less than 20 ft long or
Less than 5 ft height
Requires a condition assessment by a person trained and qualified, based on Regional Guidance.
Minor Trail Bridge. A trail bridge or other trail structure that is less than 20 feet long or less than 5 feet high (as measured from the ground or stream channel to the top of the deck of the bridge or other structure); that requires general condition assessment expertise for routine inspections; and whose failure poses no significant risk to the public.

25. Wood and <20 ft long or <5 ft above stream
MINOR TRAIL BRIDGE
Wood and <20 ft long or <5 ft above stream
Example: Sawn Lumber

26. Wood and <20 ft long or <5 ft above stream
MINOR TRAIL BRIDGE
Wood and <20 ft long or <5 ft above stream
Example: Log Stringer

27. This class is only for Minor and Major trail bridges
Quick Summary so Far
WHY WE INSPECT TRAIL BRIDGES SAFETY!!!!
WHAT IS A BRIDGE?
A structure erected over a depression or obstruction such as water that provides a continuous pathway and has a deck for carrying traffic or other loads.
WHAT ARE THE THREE CLASSIFICATIONS OF TRAIL BRIDGES?
* Complex *Major *Minor
This class is only for Minor and Major trail bridges

28. Bridge Terminology
Clear Span – Distance between face of support.

29. Bridge Orientation Terminology
APPROACH
DOWNSTREAM
RIGHT
UPSTREAM
LEFT

30. Span Arrangements
SINGLE or SIMPLE SPAN

31. Span Arrangements MULTIPLE SIMPLE SPAN
Simple Span – many spans, but each acts independently

32. Span Arrangements MULTIPLE CONTINUOUS SPAN
Continuous Spans – 1 girder spans across 2 or more supports

33. Approach Types
Gravel and Steps
Gravel

34. Rail System
Curbs, rails, posts, and bracing provided for user Safety

35. Deck
The Deck supports loads applied to the bridge

36. Decking Types & Terms Planks Wearing Surface Glulam panels
Split logs
Puncheon
Wearing Surface
Running plank
Non-skid
Gravel

37. Superstructure
The Superstructure carries loads from the deck to the substructure.

38. Superstructure Components
Is it a girder or a stringer?
GLULAM GIRDER
LOG STRINGER
SAWN BEAM
Girders or stringers or beams – main load carrying members
Diaphragms or bridging or cross bracing – provide lateral support to girders (help stabilize the girders)
Backwalls – attached to the ends of the girders or stringers.

39. Diaphragms (*), Bridging, Cross Bracing
Superstructure *
Diaphragms (*), Bridging, Cross Bracing

40. Log Stringer, aka Footlog
Superstructure
Log Stringer, aka Footlog

41. Substructure
The Substructure carries loads to the ground

42. Substructure Types
Sills or Ledgers

43. Substructure Types
Cribs and Gabions

44. Substructure Types
Columns, piers, piles, bents

45. Stream Channel This stream channel is fairly stable
But stream channels may have problem with aggradation, degradation and floating debris.

46. Stream Channel
Bank and bank protection, debris in the waterway, streambed movement

47. Stream Channel Aggradation is the accumulation of sediment in rivers
Aggradation in geology is the accumulation of sediment in rivers and nearby landforms. Aggradation occurs when sediment supply exceeds the ability of a river to transport the sediment. As an example, the quantity of sediment entering a river channel may increase when climate becomes drier. The increase in sediment is caused by a decrease in soil binding that results from plant growth being suppressed. The drier conditions cause river flow to decrease at the same time as sediment is being supplied in greater quantities. Hence, the river becomes choked with sediment.
Aggradation is the accumulation of sediment in rivers

48. Stream Channel
Degradation is erosion of the streambed

49. Floating Debris can be trees and/or vegetation
Stream Channel
Floating Debris can be trees and/or vegetation

50. SCOUR is loss of ground support

51. is localized scour under a Substructure
“Undermining”
is localized scour under a Substructure

52. Scour
Scour failure is most common in bridges that are too short

53. Scour
Scour failure is also common in areas where the banks are weak and unprotected by vegetation or riprap

54. Is this substructure fully supported?
Scour
Is this substructure fully supported?

55. Reviewing Bridge Terminology Isn’t this fun?
Railing
Deck
Approach
Substructure
(Sill)
Superstructure
(Log Stringer)

56. HOW A BRIDGE WORKS Live Loads are applied to the DECK.
The DECK transmits live loads and
deck dead load to the SUPERSTRUCTURE.
The SUPERSTRUCTURE transmits these loads and
the superstructure dead load to the SUBSTRUCTURE.
Deck
Substructure
Superstructure
Earth

57. HOW A BRIDGE WORKS
The SUBSTRUCTURE transmits all these loads and the substructure dead load to the EARTH.
The EARTH supports the bridge and all its loads
It’s all about LOAD PATHS.
Deck
Substructure
Superstructure
Earth

58. Loads and Forces Acting on the Bridge
Dead Load – weight of bridge and its components
Live Load – temporary loads
Soil Reaction – support from the earth

59. are determined by bridge materials and design
Dead Loads
are determined by bridge materials and design

60. include weight of stringers, decking, and railing
Dead Loads
include weight of stringers, decking, and railing

61. Live Loads are loads placed on the bridge
People, pack animals, ATV’s, groomers…

62. … also include snow, wind, and earthquakes…
Live Loads
… also include snow, wind, and earthquakes…

63. is the ground supporting the structure
Soil Reaction
is the ground supporting the structure

64. How does a bridge react to loads?
SCOUR
MOMENT
SHEAR
torsion
Is there going to be math?

65. SHEAR and MOMENT
SHEAR forces are greatest at the ends of the bridge. They are critical in the design of SHORT bridges.
MOMENT, or BENDING, forces are greatest in the middle of the bridge. They are critical in the design of LONG bridges.
compression
tension

66. Shear
SHEAR FORCES are highest at the ends of a bridge. Shear failure is common in short spans

67. Moment
MOMENT FORCES are highest at the middle of the bridge. Bending failure is common in long spans

68. Wood Terminology
We can break the terminology for wood into three groups:
Basic Wood Definitions
Natural Defect of Wood
Evaluation or Inspection Terms

69. Basic Wood Definitions
Different timber shapes are used for different applications.
Beams can either be rectangular for sawn or glulam beam bridges or round for log stringer bridges.

70. Basic Wood Definitions
Dimension Lumber. Lumber with a nominal thickness of from 2 inches up to, but not including, 5 inches and having a nominal width of 2 inches or greater.
Rough Lumber. Lumber that has not been dressed but that has been sawn, edged, and trimmed.
Sawn Lumber. The product of a sawmill not further manufactured other than by sawing, re-sawing and cross-cutting to length.
Beams and Stringers (B&S) Beams and stringers are rectangular pieces that are 5.0 or more in. thick, with a depth more than 2.0 in. greater than the thickness. B&S are graded primarily for use as beams, with loads applied to the narrow face.
Bent. A type of pier consisting of two or more columns or column-like components connected at their top ends by a cap, strut, or other component holding them in their correct positions.
Cap A sawn lumber or glulam component placed horizontally on an abutment or pier to distribute the live load and dead load of the superstructure. Also, a metal, wood, or mastic cover to protect exposed wood end grain from wetting.
Clear Span. Inside distance between the faces of support.
Connector. Synonym for fastener.
Crib A structure consisting of a foundation grillage and a framework providing compartments that are filled with gravel, stones, or other material satisfactory for supporting the structure to be placed thereon.
Decking. A subcategory of dimension lumber, graded primarily for use with the wide face placed flatwise.
Diaphragm. Blocking between two main longitudinal beams consisting of solid lumber, glued laminated timber, or steel X-bracing.
Dimension Lumber. Lumber with a nominal thickness of from 2.0 up to but not including 5.0 in. and having a nominal width of 2.0 in. or more.
Dressed Size. The dimensions of lumber after being surfaced with a planing machine. The dressed size is usually 1/2 to 3/4 in. less than the nominal or rough size. A 2- by 4-in. stud, for example, actually measures about 1-1/2 by 3-1/2 in.
Fastener. Generic term for individual mechanical devices such as bolts, nails, etc., used in a connection.
Glued Laminated Timber (glulam). An engineered, stress-rated product of a timber laminating plant comprised of assemblies of specially selected and prepared wood laminations securely bonded together with adhesives.
Grain. The direction, size, arrangement, appearance, or quality of the fibers in wood or lumber.
Green Wood. A freshly sawn or undried wood. Wood that has become completely wet after immersion in water would not be considered green but may be said to be in the green condition.
Incising. A pretreatment process in which incisions, slits, or perforations are made in the wood surface to increase penetration of preservative treatments. Incising is often required to enhance durability of some difficult-to-treat species, but incising reduces strength.
Log Stringer. Round logs that are used as beams or stringers that have been debarked.
Lumber. The product of the saw and planing mill for which manufacturing is limited to sawing, re-sawing, passing lengthwise through a standard planing machine, crosscutting to length, and matching. Lumber may be made from either softwood or hardwood
Moisture Content (MC). The amount of water contained in the wood, usually expressed as a percentage of the weight of the oven dry wood.
NDS. National Design Standards by the National Forest Products Association.
Nominal Size. As applied to timber or lumber, the size by which it is known and sold in the market (often differs from the actual size).
Oil-Borne Preservative. A preservative that is introduced into wood in the form of an oil-based solution.
Pile. A long, heavy timber, round or square, that is driven deep into the ground to provide a secure foundation for structures built on soft, wet, or submerged sites.
Plank. A broad board, usually more than 1.0 in. thick, laid with its wide dimension horizontal and used as a bearing surface.
Pole. A round timber of any size or length, usually used with the large end in the ground.
Posts. Posts are round or square pieces with a cross-section, 5.0 by 5.0 in. and larger.
Preservative. Any substance that is effective in preventing the development and action of wood-decaying fungi, borers of various kinds, and harmful insects that deteriorate wood.
Rough Lumber. Lumber that has not been dressed but that has been sawn, edged, and trimmed.
Sawn Lumber. The product of a sawmill not further manufactured other than by sawing, re-sawing, passing lengthwise through a standard planing mill, and cross-cutting to length.
Sill. Timbers used as an abutment to support beams.
Structural Lumber. Lumber that is intended for use where allowable properties are required. The grading of structural lumber is based on the strength or stiffness of the piece as related to anticipated uses.
Structural Timbers. Pieces of wood of relatively large size, the strength or stiffness of which is the controlling element in their selection and use. Examples of structural timbers are trestle timbers (stringers, caps, posts, sills, bracing, bridge ties, guardrails); car timbers (car framing, including upper framing, car sills); framing for building (posts, sills, girders); ship timber (ship timbers, ship decking); and crossarms for poles.
Surfaced Lumber. Lumber that is dressed by running it through a planer.
Timbers. Lumber that is nominally 5.0 in. or more in least dimension. Timbers may be used as beams, stringers, posts, caps, sills, girders, or purlins.
Timbers, Round. Timbers used in the original round form, such as poles, piling, posts, and mine timbers.
Twist. A distortion caused by the turning or winding of the edges of a board so that the four comers of any face are no longer in the same plane. For logs, it is the rotating of the grain in the log.
Wane. Bark or lack of wood from any cause on edge or corner of a piece except for eased edges.
Warp. Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist, or any combination thereof.
Waterborne Preservative. A preservative that is introduced into wood in the form of a water-based solution.

71. Basic Wood Definitions
Glued Laminated Timber (glulam). An engineered, stress-rated product of a timber laminating plant comprised of assemblies of specially selected and prepared wood laminations securely bonded together with adhesives.
Log Stringer. Round logs that are used as beams or stringers that have been debarked.
Timbers. Lumber that is nominally 5 inches or more in least dimension.
Beams and Stringers (B&S) Beams and stringers are rectangular pieces that are 5.0 or more in. thick, with a depth more than 2.0 in. greater than the thickness. B&S are graded primarily for use as beams, with loads applied to the narrow face.
Bent. A type of pier consisting of two or more columns or column-like components connected at their top ends by a cap, strut, or other component holding them in their correct positions.
Cap A sawn lumber or glulam component placed horizontally on an abutment or pier to distribute the live load and dead load of the superstructure. Also, a metal, wood, or mastic cover to protect exposed wood end grain from wetting.
Clear Span. Inside distance between the faces of support.
Connector. Synonym for fastener.
Crib A structure consisting of a foundation grillage and a framework providing compartments that are filled with gravel, stones, or other material satisfactory for supporting the structure to be placed thereon.
Decking. A subcategory of dimension lumber, graded primarily for use with the wide face placed flatwise.
Diaphragm. Blocking between two main longitudinal beams consisting of solid lumber, glued laminated timber, or steel X-bracing.
Dimension Lumber. Lumber with a nominal thickness of from 2.0 up to but not including 5.0 in. and having a nominal width of 2.0 in. or more.
Dressed Size. The dimensions of lumber after being surfaced with a planing machine. The dressed size is usually 1/2 to 3/4 in. less than the nominal or rough size. A 2- by 4-in. stud, for example, actually measures about 1-1/2 by 3-1/2 in.
Fastener. Generic term for individual mechanical devices such as bolts, nails, etc., used in a connection.
Glued Laminated Timber (glulam). An engineered, stress-rated product of a timber laminating plant comprised of assemblies of specially selected and prepared wood laminations securely bonded together with adhesives.
Grain. The direction, size, arrangement, appearance, or quality of the fibers in wood or lumber.
Green Wood. A freshly sawn or undried wood. Wood that has become completely wet after immersion in water would not be considered green but may be said to be in the green condition.
Incising. A pretreatment process in which incisions, slits, or perforations are made in the wood surface to increase penetration of preservative treatments. Incising is often required to enhance durability of some difficult-to-treat species, but incising reduces strength.
Log Stringer. Round logs that are used as beams or stringers that have been debarked.
Lumber. The product of the saw and planing mill for which manufacturing is limited to sawing, re-sawing, passing lengthwise through a standard planing machine, crosscutting to length, and matching. Lumber may be made from either softwood or hardwood
Moisture Content (MC). The amount of water contained in the wood, usually expressed as a percentage of the weight of the oven dry wood.
NDS. National Design Standards by the National Forest Products Association.
Nominal Size. As applied to timber or lumber, the size by which it is known and sold in the market (often differs from the actual size).
Oil-Borne Preservative. A preservative that is introduced into wood in the form of an oil-based solution.
Pile. A long, heavy timber, round or square, that is driven deep into the ground to provide a secure foundation for structures built on soft, wet, or submerged sites.
Plank. A broad board, usually more than 1.0 in. thick, laid with its wide dimension horizontal and used as a bearing surface.
Pole. A round timber of any size or length, usually used with the large end in the ground.
Posts. Posts are round or square pieces with a cross-section, 5.0 by 5.0 in. and larger.
Preservative. Any substance that is effective in preventing the development and action of wood-decaying fungi, borers of various kinds, and harmful insects that deteriorate wood.
Rough Lumber. Lumber that has not been dressed but that has been sawn, edged, and trimmed.
Sawn Lumber. The product of a sawmill not further manufactured other than by sawing, re-sawing, passing lengthwise through a standard planing mill, and cross-cutting to length.
Sill. Timbers used as an abutment to support beams.
Structural Lumber. Lumber that is intended for use where allowable properties are required. The grading of structural lumber is based on the strength or stiffness of the piece as related to anticipated uses.
Structural Timbers. Pieces of wood of relatively large size, the strength or stiffness of which is the controlling element in their selection and use. Examples of structural timbers are trestle timbers (stringers, caps, posts, sills, bracing, bridge ties, guardrails); car timbers (car framing, including upper framing, car sills); framing for building (posts, sills, girders); ship timber (ship timbers, ship decking); and crossarms for poles.
Surfaced Lumber. Lumber that is dressed by running it through a planer.
Timbers. Lumber that is nominally 5.0 in. or more in least dimension. Timbers may be used as beams, stringers, posts, caps, sills, girders, or purlins.
Timbers, Round. Timbers used in the original round form, such as poles, piling, posts, and mine timbers.
Twist. A distortion caused by the turning or winding of the edges of a board so that the four comers of any face are no longer in the same plane. For logs, it is the rotating of the grain in the log.
Wane. Bark or lack of wood from any cause on edge or corner of a piece except for eased edges.
Warp. Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist, or any combination thereof.
Waterborne Preservative. A preservative that is introduced into wood in the form of a water-based solution.

72. Basic Wood Definitions
Dressed Size. The dimensions of lumber after being surfaced with a planing machine. The dressed size is usually 1/2 to 3/4 in. less than the nominal or rough size. A 2- by 4-in. stud, for example, actually measures about 1-1/2 by 3-1/2 in.
Nominal Size. As applied to timber or lumber, the size by which it is known and sold in the market i.e, 2x4, 2x6,4x4,etc. (often differs from the actual size).
Beams and Stringers (B&S) Beams and stringers are rectangular pieces that are 5.0 or more in. thick, with a depth more than 2.0 in. greater than the thickness. B&S are graded primarily for use as beams, with loads applied to the narrow face.
Bent. A type of pier consisting of two or more columns or column-like components connected at their top ends by a cap, strut, or other component holding them in their correct positions.
Cap A sawn lumber or glulam component placed horizontally on an abutment or pier to distribute the live load and dead load of the superstructure. Also, a metal, wood, or mastic cover to protect exposed wood end grain from wetting.
Clear Span. Inside distance between the faces of support.
Connector. Synonym for fastener.
Crib A structure consisting of a foundation grillage and a framework providing compartments that are filled with gravel, stones, or other material satisfactory for supporting the structure to be placed thereon.
Decking. A subcategory of dimension lumber, graded primarily for use with the wide face placed flatwise.
Diaphragm. Blocking between two main longitudinal beams consisting of solid lumber, glued laminated timber, or steel X-bracing.
Dimension Lumber. Lumber with a nominal thickness of from 2.0 up to but not including 5.0 in. and having a nominal width of 2.0 in. or more.
Dressed Size. The dimensions of lumber after being surfaced with a planing machine. The dressed size is usually 1/2 to 3/4 in. less than the nominal or rough size. A 2- by 4-in. stud, for example, actually measures about 1-1/2 by 3-1/2 in.
Fastener. Generic term for individual mechanical devices such as bolts, nails, etc., used in a connection.
Glued Laminated Timber (glulam). An engineered, stress-rated product of a timber laminating plant comprised of assemblies of specially selected and prepared wood laminations securely bonded together with adhesives.
Grain. The direction, size, arrangement, appearance, or quality of the fibers in wood or lumber.
Green Wood. A freshly sawn or undried wood. Wood that has become completely wet after immersion in water would not be considered green but may be said to be in the green condition.
Incising. A pretreatment process in which incisions, slits, or perforations are made in the wood surface to increase penetration of preservative treatments. Incising is often required to enhance durability of some difficult-to-treat species, but incising reduces strength.
Log Stringer. Round logs that are used as beams or stringers that have been debarked.
Lumber. The product of the saw and planing mill for which manufacturing is limited to sawing, re-sawing, passing lengthwise through a standard planing machine, crosscutting to length, and matching. Lumber may be made from either softwood or hardwood
Moisture Content (MC). The amount of water contained in the wood, usually expressed as a percentage of the weight of the oven dry wood.
NDS. National Design Standards by the National Forest Products Association.
Nominal Size. As applied to timber or lumber, the size by which it is known and sold in the market (often differs from the actual size).
Oil-Borne Preservative. A preservative that is introduced into wood in the form of an oil-based solution.
Pile. A long, heavy timber, round or square, that is driven deep into the ground to provide a secure foundation for structures built on soft, wet, or submerged sites.
Plank. A broad board, usually more than 1.0 in. thick, laid with its wide dimension horizontal and used as a bearing surface.
Pole. A round timber of any size or length, usually used with the large end in the ground.
Posts. Posts are round or square pieces with a cross-section, 5.0 by 5.0 in. and larger.
Preservative. Any substance that is effective in preventing the development and action of wood-decaying fungi, borers of various kinds, and harmful insects that deteriorate wood.
Rough Lumber. Lumber that has not been dressed but that has been sawn, edged, and trimmed.
Sawn Lumber. The product of a sawmill not further manufactured other than by sawing, re-sawing, passing lengthwise through a standard planing mill, and cross-cutting to length.
Sill. Timbers used as an abutment to support beams.
Structural Lumber. Lumber that is intended for use where allowable properties are required. The grading of structural lumber is based on the strength or stiffness of the piece as related to anticipated uses.
Structural Timbers. Pieces of wood of relatively large size, the strength or stiffness of which is the controlling element in their selection and use. Examples of structural timbers are trestle timbers (stringers, caps, posts, sills, bracing, bridge ties, guardrails); car timbers (car framing, including upper framing, car sills); framing for building (posts, sills, girders); ship timber (ship timbers, ship decking); and crossarms for poles.
Surfaced Lumber. Lumber that is dressed by running it through a planer.
Timbers. Lumber that is nominally 5.0 in. or more in least dimension. Timbers may be used as beams, stringers, posts, caps, sills, girders, or purlins.
Timbers, Round. Timbers used in the original round form, such as poles, piling, posts, and mine timbers.
Twist. A distortion caused by the turning or winding of the edges of a board so that the four comers of any face are no longer in the same plane. For logs, it is the rotating of the grain in the log.
Wane. Bark or lack of wood from any cause on edge or corner of a piece except for eased edges.
Warp. Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist, or any combination thereof.
Waterborne Preservative. A preservative that is introduced into wood in the form of a water-based solution.

73. Wood Related Definitions
Fastener. Generic term for individual mechanical devices such as bolts, nails, etc., used in a connection.
Oil-Borne Preservative. A preservative that is introduced into wood in the form of an oil-based solution.
Waterborne Preservative. A preservative that is introduced into wood in the form of a water-based solution.
Beams and Stringers (B&S) Beams and stringers are rectangular pieces that are 5.0 or more in. thick, with a depth more than 2.0 in. greater than the thickness. B&S are graded primarily for use as beams, with loads applied to the narrow face.
Bent. A type of pier consisting of two or more columns or column-like components connected at their top ends by a cap, strut, or other component holding them in their correct positions.
Cap A sawn lumber or glulam component placed horizontally on an abutment or pier to distribute the live load and dead load of the superstructure. Also, a metal, wood, or mastic cover to protect exposed wood end grain from wetting.
Clear Span. Inside distance between the faces of support.
Connector. Synonym for fastener.
Crib A structure consisting of a foundation grillage and a framework providing compartments that are filled with gravel, stones, or other material satisfactory for supporting the structure to be placed thereon.
Decking. A subcategory of dimension lumber, graded primarily for use with the wide face placed flatwise.
Diaphragm. Blocking between two main longitudinal beams consisting of solid lumber, glued laminated timber, or steel X-bracing.
Dimension Lumber. Lumber with a nominal thickness of from 2.0 up to but not including 5.0 in. and having a nominal width of 2.0 in. or more.
Dressed Size. The dimensions of lumber after being surfaced with a planing machine. The dressed size is usually 1/2 to 3/4 in. less than the nominal or rough size. A 2- by 4-in. stud, for example, actually measures about 1-1/2 by 3-1/2 in.
Fastener. Generic term for individual mechanical devices such as bolts, nails, etc., used in a connection.
Glued Laminated Timber (glulam). An engineered, stress-rated product of a timber laminating plant comprised of assemblies of specially selected and prepared wood laminations securely bonded together with adhesives.
Grain. The direction, size, arrangement, appearance, or quality of the fibers in wood or lumber.
Green Wood. A freshly sawn or undried wood. Wood that has become completely wet after immersion in water would not be considered green but may be said to be in the green condition.
Incising. A pretreatment process in which incisions, slits, or perforations are made in the wood surface to increase penetration of preservative treatments. Incising is often required to enhance durability of some difficult-to-treat species, but incising reduces strength.
Log Stringer. Round logs that are used as beams or stringers that have been debarked.
Lumber. The product of the saw and planing mill for which manufacturing is limited to sawing, re-sawing, passing lengthwise through a standard planing machine, crosscutting to length, and matching. Lumber may be made from either softwood or hardwood
Moisture Content (MC). The amount of water contained in the wood, usually expressed as a percentage of the weight of the oven dry wood.
NDS. National Design Standards by the National Forest Products Association.
Nominal Size. As applied to timber or lumber, the size by which it is known and sold in the market (often differs from the actual size).
Oil-Borne Preservative. A preservative that is introduced into wood in the form of an oil-based solution.
Pile. A long, heavy timber, round or square, that is driven deep into the ground to provide a secure foundation for structures built on soft, wet, or submerged sites.
Plank. A broad board, usually more than 1.0 in. thick, laid with its wide dimension horizontal and used as a bearing surface.
Pole. A round timber of any size or length, usually used with the large end in the ground.
Posts. Posts are round or square pieces with a cross-section, 5.0 by 5.0 in. and larger.
Preservative. Any substance that is effective in preventing the development and action of wood-decaying fungi, borers of various kinds, and harmful insects that deteriorate wood.
Rough Lumber. Lumber that has not been dressed but that has been sawn, edged, and trimmed.
Sawn Lumber. The product of a sawmill not further manufactured other than by sawing, re-sawing, passing lengthwise through a standard planing mill, and cross-cutting to length.
Sill. Timbers used as an abutment to support beams.
Structural Lumber. Lumber that is intended for use where allowable properties are required. The grading of structural lumber is based on the strength or stiffness of the piece as related to anticipated uses.
Structural Timbers. Pieces of wood of relatively large size, the strength or stiffness of which is the controlling element in their selection and use. Examples of structural timbers are trestle timbers (stringers, caps, posts, sills, bracing, bridge ties, guardrails); car timbers (car framing, including upper framing, car sills); framing for building (posts, sills, girders); ship timber (ship timbers, ship decking); and crossarms for poles.
Surfaced Lumber. Lumber that is dressed by running it through a planer.
Timbers. Lumber that is nominally 5.0 in. or more in least dimension. Timbers may be used as beams, stringers, posts, caps, sills, girders, or purlins.
Timbers, Round. Timbers used in the original round form, such as poles, piling, posts, and mine timbers.
Twist. A distortion caused by the turning or winding of the edges of a board so that the four comers of any face are no longer in the same plane. For logs, it is the rotating of the grain in the log.
Wane. Bark or lack of wood from any cause on edge or corner of a piece except for eased edges.
Warp. Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist, or any combination thereof.
Waterborne Preservative. A preservative that is introduced into wood in the form of a water-based solution.

74. Natural Defects of Wood
Check – A separation of the wood normally occurring across or through the rings of annual growth and usually as a result of seasoning.
Split – A separation of the wood through the piece to the opposite surface or to an adjoining surface due to the tearing apart of wood cells.
Shake – A lengthwise separation of the wood which occurs between or through the rings of annual growth.

75. Natural Defect of Wood
Check. A lengthwise separation of the wood that usually extends across the rings of annual growth and commonly results from stresses set up in wood during seasoning.
Creep. (1) Time dependent deformation of a wood member under sustained wood. (2) In an adhesive, the time-dependent increase in strain resulting from a sustained stress.
Knot. That portion of a branch or limb that has been surrounded by subsequent growth of the stem. The shape of the knot as it appears on a cut surface depends on the angle of the cut relative to the long axis of the knot.
Shake. A separation along the grain, the greater part of which occurs between the rings of annual growth. Usually considered to have occurred in the standing tree or during felling.
Split. A separation of the wood through the piece to the opposite surface or to an adjoining surface due to the tearing apart of wood cells.
Twist. A distortion caused by the turning or winding of the edges of a board so that the four comers of any face are no longer in the same plane. For logs, it is the rotating of the grain in the log.
Wane. Bark or lack of wood from any cause on edge or corner of a piece except for eased edges.
Warp. Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist, or any combination thereof.

76. Checks
Seasoning checks may occur in the wide side of a member at or near the neutral axis.
The cracks form because the wood near the surface dries and shrinks first.
In larger pieces of lumber, the inner core of the member loses moisture and shrinks much slower.
Checking relieves the stresses caused by non-uniform drying.

77. Checks

78. Checks

79. Split

80. Shake

81. Inspection Terms
Crack – Complete separation of wood fibers across short axis of wood cells
Decay*** - Decomposition of wood substance by fungi. Some people refer to it as “rot”
Delamination. The separation of layers in laminated wood or plywood because of failure of the adhesive, either within the adhesive itself or at the interface between the adhesive and the adhered.
*** Will be covered in the classroom in more detail.
Crack – Complete separation of wood fibers across short access of wood cells
Decay. The decomposition of wood substance by fungi. Some people refer to it as “rot”.
Delamination. The separation of layers in laminated wood or plywood because of failure of the adhesive, either within the adhesive itself or at the interface between the adhesive and the adhered.
Moisture Content (MC). The amount of water contained in the wood, usually expressed as a percentage of the weight of the oven dry wood.
Twist. A distortion caused by the turning or winding of the edges of a board so that the four comers of any face are no longer in the same plane. For logs, it is the rotating of the grain in the log.
Warp. Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist, or any combination thereof.
Weathering. The mechanical or chemical disintegration and discoloration of the surface of wood caused by exposure to light, the action of dust and sand carried by winds, and the alternate shrinking and swelling of the surface fibers with the continual variation in moisture content brought by changes in the weather. Weathering does not include decay.

82. Crack

83. Other Inspection Terms
Moisture Content (MC). The amount of water contained in the wood, usually expressed as a percentage of the weight of the oven dry wood.
Twist. A distortion caused by the turning or winding of the edges of a board so that the four corners of any face are no longer in the same plane.
Warp. Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist, or any combination thereof.
Weathering. The mechanical or chemical disintegration and discoloration of the surface of wood caused by exposure to light, the action of dust and sand carried by winds. Weathering does not include decay.
Crack – Complete separation of wood fibers across short access of wood cells
Decay. The decomposition of wood substance by fungi. Some people refer to it as “rot”.
Delamination. The separation of layers in laminated wood or plywood because of failure of the adhesive, either within the adhesive itself or at the interface between the adhesive and the adhered.
Moisture Content (MC). The amount of water contained in the wood, usually expressed as a percentage of the weight of the oven dry wood.
Twist. A distortion caused by the turning or winding of the edges of a board so that the four comers of any face are no longer in the same plane. For logs, it is the rotating of the grain in the log.
Warp. Any variation from a true or plane surface. Warp includes bow, crook, cup, and twist, or any combination thereof.
Weathering. The mechanical or chemical disintegration and discoloration of the surface of wood caused by exposure to light, the action of dust and sand carried by winds, and the alternate shrinking and swelling of the surface fibers with the continual variation in moisture content brought by changes in the weather. Weathering does not include decay.

84. Inspection Tools & Equipment
Basic inspection tools & equipment consists of:
Backpack
Light
Boots
Pick
Awl

85. Backpack
A good backpack is needed to store and carry your tools to the bridge site.

86. Boots or Waders
A set of waders or boots are required for walking in the water to inspect the underside of bridges.
Boots with felt soles work well walking in areas with slippery rocks.

87. Prospector’s Pick
A prospector’s pick works well for sounding logs and beams with the hammer side and checking for decay with the pick side.

88. Probes
Narrow screw drivers and awls work best for checking for decay in wood members.
Locking knives may be used, but are strongly discouraged. Knives that do not lock should not be used.

89. Lights A good light for use under bridges is highly recommended.
Both for safety and to perform a good bridge inspection.
Shining the light under a bridge before entering is a good safety practice, while it helps the inspector see animals and other obstacles that may cause problems.

90. Optional Tools
A pair of binoculars is good for looking at the underside of a bridge when you can not get right up on the member you need to look at.
A telescoping pole can be used to look for scour holes and help to steady the inspector while walking in the stream.

91. Optional Tools
A mirror can be used for inspecting hard to reach locations or around corners.
A plumb bob will help to check if things are perpendicular to the ground.
A wrench can be used for checking bolt tightness.

92. Essential Items Don’t forget the essentials!!!
Duck tape for fixing everything and toilet paper for when nature calls.

93. Record Keeping Basic record keeping tools are: Clipboard
Inspection Forms
Write-in-rain notebook
Pencils
Camera
Maps
Basic record keeping tools are a clipboard, inspection forms, write-in-rain notebook, pencils, camera and maps.

94. Maps Getting lost is not fun.
Maps are a necessity for working for the Forest Service.
Getting lost is not fun.
Maps are a necessity for working for the Forest Service. Getting lost is not fun.
Taking the time to mark the location of the trail bridge on map make them easier to find in the field.
Taking the time to mark the location of the trail bridges on the map makes them easier to find in the field

95. Bridge Inspection Forms & Tools
Make sure you have enough pencils, write-in-the-rain paper, forms and a clipboard to write on before going into the field.

96. Camera
Take a camera along and take lots of pictures and document any deficiencies or problems.

97. Optional Recording Tools
Other optional tools maybe a straight edge, triangles, compass and scale for drawing up sketches of the bridge.
Who knows, a calculator may even be handy to have.

98. Surveying Equipment
Surveying equipment will be used for taking measurements of the bridge. The basics are a 6-foot rule, 25-foot tape, 100-foot cloth tape, a level and a GPS unit.

99. GPS or Compass
A GPS unit will help you from getting lost and to get the coordinates of the site.
Some people still like to use a compass in the woods.

100. Levels
Levels or a pocket level & ruler are not required, but maybe useful for checking slope of the bridge and settlement of the structure.

101. Measuring Devices
Tapes and rulers should be used to take measurements of the bridge and problems. At minimum, the inspector should carry a 6-foot rule and a 100-foot cloth tape.

102. Safety Equipment Basic Safety Equipment consists of: Hard Hat
Safety Glasses
Orange Vest
Gloves
Cell Phone
Hiking Boots
Basic Safety Equipment consist of:
Hard Hat
Safety Glasses
Orange Surveyors Vest
Gloves
Cell Phone
Hiking Boots

103. Hard Hat
Hard Hats are required to protect your head from running into sharp or protruding objects under the bridge.
Hard Hats protect your head from sharp or protruding objects under the bridge.

104. Safety Glasses & Gloves
Glasses protects eyes from flying debris when sounding timbers and sharp objects when walking under bridge
Safety glasses or goggles and gloves should be used while inspecting bridges.
Glasses protect from flying debris when sounding timbers and sharp objects when walking under bridge.
Gloves protect hands from blisters, slivers and cuts. They also protect against biting insects and poisonous plants.
Gloves protect hands from blisters, slivers and cuts. They also protect against biting insects and poisonous plants.

105. Boots
Boots should provide ankle support to prevent sprains and twisted ankles
The treads should provide good traction
Boots are required with good ankle support to prevent sprains and twisted ankles.
The treads should provide good traction.
Boots should fit properly to avoid causing blisters and be broken in.

106. Safety Vests
Safety vests are needed to provide visibility from traffic using the trail.
Either a orange surveyor vest or highway safety vest maybe used.
Orange surveyor vests work best for carrying inspection equipment.
The highway safety vests may be a better choice for high capacity ATV trails.
Safety vests are needed to provide visibility from traffic using the trail

107. Communications
A proper communication device should be carried at all times in case of emergency
A proper communication device should be carried at all times in case of emergency.
Either Forest Service Radios, cell and satellite phones should be used depending on phone or radio reception.
The inspector should follow the Administrative Tracking Policy for check-out/check-in procedures before going out into the field.
Examples are Forest Service Radios, cell and satellite phones

108. First Aid Kit
A first aid kit should be carried into the field for emergency use.
A first aid kit should be carried into the field for emergency use.

109. Optional Safety Equipment
Optional safety equipment can include:
Snake Chaps
Bear Spray
Insect Repellent
Sun Screen
Rain Gear
Coveralls
Optional safety equipment can include snake chaps, bear spray, insect repellent, sun screen, rain gear and coveralls.

110. Snake Chaps (optional)
Snake chaps should be worn in areas where poisonous snakes are known to live.
Snake chaps should be worn in areas where poisonous snakes are known to live.
Do not provoke or handle snakes.
Do not provoke or handle snakes.

111. Insect Repellent & Sunscreen (optional)
Insect repellent should be used when mosquitoes, flies and other biting bugs are present.
In addition, long sleeve shirts and pants should be worn. Gloves and head nets may also be a good idea.
Insect repellent should be used when mosquitoes, flies and other biting bugs are present. In addition, long sleeve shirts and pants should be worn. Gloves and head nets may also be a good idea.
The same holds true for sun screen. Prevent sunburn by wearing long sleeves and hard hat. Use sun screen if needed.
The same holds true for sun screen. Prevent sunburn by wearing long sleeves and hard hat. Use sun screen if needed.

112. Rain Gear (optional)
A light weight packable rain coat is a great way to go.
You need to wear clothing suited to the weather.
A light weight packable rain coat is a great way to go.
You need to wear clothing suited to the weather.
A layering approach works best for working in unpredictable weather conditions.
A layering approach works best for working in unpredictable weather conditions.

113. Acknowledgments
Thanks to R6 & R10 bridge engineers for their past training presentations and information to help develop this training.
Thanks to Michael Knutson and John Kattell for reviewing the training.

114. References FHWA Bridge Inspection Reference Manual
FHWA Field Manual for Timber Bridge Inspection, Draft
FPL Timber Bridges Design, Construction, Inspection and Maintenance
FSM 7736
FSH b, Chapter 8
R1 Major Trail Bridge Inspection Form & Minor Trail Bridge Condition Assessment Form
R2 Trail Bridge Inspection Guidelines
R4 Trail Bridge Inspection Guidelines
R6 Trail Bridge Inspection
R10 Training PowerPoints