49.1 Introduction
Before the 1960s, little emphasis was given to inspection and maintenance of bridges in the United States. After the 1967 tragic collapse of the Silver Bridge at Point Pleasant in West Virginia, national interest in the inspection and maintenance rose considerably. The U.S. Congress passed the Federal Highway Act of 1968 which resulted in the establishment of the National Bridge Inspection Standard (NBIS). The NBIS sets the national policy regarding bridge inspection procedure, inspection frequency, inspector qualifications, reporting format, and rating procedures. In addition to the establishment of NBIS, three manuals — FHWA Bridge Inspectorrsquo;s Training Manual 70 , AASHO Manual for Maintenance Inspection of Bridges , and FHWA Recording and Coding Guide for the Structure Inventory and Appraisal of the Nationrsquo;s Bridges — have been developed and updated since the 1970s. These manuals along with the NBIS provide definitive guidelines for bridge inspection. Over the past three decades, the bridge inspection program evolved into one of the most-sophisticated bridge management systems. This chapter will focus only on the basic,fundamental requirements for maintenance inspection and rating.
49.2 Maintenance Documentation
Each bridge document needs to have items such as structure information, structural data and history, description on and below the structure, traffic information, load rating, condition and appraisal
ratings, and inspection findings. The inspection findings should have the signature of the inspection team leader.
All states in the United States are encouraged, but not mandated, to use the codes and instructions
given in the Recording and Coding Guide while documenting the bridge inventory. In order to maintain the nationrsquo;s bridge inventory, FHWA requests all state agencies to submit data on the Structure Inventory and Appraisal (SIamp;A) Sheet. The SIamp;A sheet is a tabulation of pertinent information about an individual bridge. The information on SIamp;A sheet is a valuable aid to establish maintenance and replacement priorities and to determine the maintenance cost of the nationrsquo;s bridges.
49.3 Fundamentals of Bridge Inspection
49.3.1 Qualifications and Responsibilities of Bridge Inspectors
The primary purpose of bridge inspection is to maintain the public safety, confidence, and investment in bridges. Ensuring public safety and investment decision requires a comprehensive bridge inspection. To this end, a bridge inspector should be knowledgeable in material and structural behavior, bridge design, and typical construction practices. In addition, inspectors should be physically strong because the inspection sometimes requires climbing on rough, steep, and slippery terrain, working at heights, or working for days.
Some of the major responsibilities of a bridge inspector are as follows:
bull; Identifying minor problems that can be corrected before they develop into major repairs;
bull; Identifying bridge components that require repairs in order to avoid total replacement;
bull; Identifying unsafe conditions;
bull; Preparing accurate inspection records, documents, and recommendation of corrective
actions; and
bull; Providing bridge inspection program support.
In the United States, NBIS requires a field leader for highway bridge inspection teams. The field team leader should be either a professional engineer or a state certified bridge inspector, or a Level III bridge inspector certified through the National Institute for Certification of Engineering Technologies. It is the responsibility of the inspection team leader to decide the capability of individual team members and delegate their responsibilities accordingly. In addition, the team leader is responsible for the safety of the inspection team and establishing the frequency of bridge inspections.
49.3.2 Frequency of Inspection
NBIS requires that each bridge that is opened to public be inspected at regular intervals not exceeding2 years. The underwater components that cannot be visually evaluated during periods of low flow or examined by feel for their physical conditions should be inspected at an interval not exceeding 5 years.
The frequency, scope, and depth of the inspection of bridges generally depend on several parameters such as age, traffic characteristics, state of maintenance, fatigue-prone details, weight limit posting level, and known deficiencies. Bridge owners may establish the specific frequency of inspection based on the above factors.
49.3.3 Tools for Inspection
In order to perform an accurate and comprehensive inspection, proper tools must be available. As
a minimum, an inspector needs to have a 2-m (6-ft) pocket tape, a 30-m (100-ft) tape, a chipping hammer, scrapers, flat-bladed screwdriver, pocketknife, wire brush, field marking crayon, flashlight, plumb bob, binoculars, thermometer, tool belt with tool pouch, and a carrying bag. Other useful tools are a shovel, vernier or jaw-type calipers, lighted magnifying glass, inspection mirrors, dye penetrant, 1-m (4-ft) carpenterrsquo;s level, optical crack gauge, paint film gauge, and first-aid kits. Additional special inspection tools are survey, nondestructive testing, and underwater inspection equipment.
Inspection of a bridge prompts several unique challenges to bridge inspectors. One of the challenges to inspectors is the accessibility of bridge components. Most smaller bridges can be accessed from below without great effort, but larger bridges need the assistance of accessing equipment and vehicles. Common access equipment are ladders, rigging, boats or barges, floats, and scaffolds. Common access vehicles are manlifts, snoopers, aerial buckets, and tr
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49.1 Introduction
Before the 1960s, little emphasis was given to inspection and maintenance of bridges in the United States. After the 1967 tragic collapse of the Silver Bridge at Point Pleasant in West Virginia, national interest in the inspection and maintenance rose considerably. The U.S. Congress passed the Federal Highway Act of 1968 which resulted in the establishment of the National Bridge Inspection Standard (NBIS). The NBIS sets the national policy regarding bridge inspection procedure, inspection frequency, inspector qualifications, reporting format, and rating procedures. In addition to the establishment of NBIS, three manuals — FHWA Bridge Inspectorrsquo;s Training Manual 70 , AASHO Manual for Maintenance Inspection of Bridges , and FHWA Recording and Coding Guide for the Structure Inventory and Appraisal of the Nationrsquo;s Bridges — have been developed and updated since the 1970s. These manuals along with the NBIS provide definitive guidelines for bridge inspection. Over the past three decades, the bridge inspection program evolved into one of the most-sophisticated bridge management systems. This chapter will focus only on the basic,fundamental requirements for maintenance inspection and rating.
49.2 Maintenance Documentation
Each bridge document needs to have items such as structure information, structural data and history, description on and below the structure, traffic information, load rating, condition and appraisal
ratings, and inspection findings. The inspection findings should have the signature of the inspection team leader.
All states in the United States are encouraged, but not mandated, to use the codes and instructions
given in the Recording and Coding Guide while documenting the bridge inventory. In order to maintain the nationrsquo;s bridge inventory, FHWA requests all state agencies to submit data on the Structure Inventory and Appraisal (SIamp;A) Sheet. The SIamp;A sheet is a tabulation of pertinent information about an individual bridge. The information on SIamp;A sheet is a valuable aid to establish maintenance and replacement priorities and to determine the maintenance cost of the nationrsquo;s bridges.
49.3 Fundamentals of Bridge Inspection
49.3.1 Qualifications and Responsibilities of Bridge Inspectors
The primary purpose of bridge inspection is to maintain the public safety, confidence, and investment in bridges. Ensuring public safety and investment decision requires a comprehensive bridge inspection. To this end, a bridge inspector should be knowledgeable in material and structural behavior, bridge design, and typical construction practices. In addition, inspectors should be physically strong because the inspection sometimes requires climbing on rough, steep, and slippery terrain, working at heights, or working for days.
Some of the major responsibilities of a bridge inspector are as follows:
bull; Identifying minor problems that can be corrected before they develop into major repairs;
bull; Identifying bridge components that require repairs in order to avoid total replacement;
bull; Identifying unsafe conditions;
bull; Preparing accurate inspection records, documents, and recommendation of corrective
actions; and
bull; Providing bridge inspection program support.
In the United States, NBIS requires a field leader for highway bridge inspection teams. The field team leader should be either a professional engineer or a state certified bridge inspector, or a Level III bridge inspector certified through the National Institute for Certification of Engineering Technologies. It is the responsibility of the inspection team leader to decide the capability of individual team members and delegate their responsibilities accordingly. In addition, the team leader is responsible for the safety of the inspection team and establishing the frequency of bridge inspections.
49.3.2 Frequency of Inspection
NBIS requires that each bridge that is opened to public be inspected at regular intervals not exceeding2 years. The underwater components that cannot be visually evaluated during periods of low flow or examined by feel for their physical conditions should be inspected at an interval not exceeding 5 years.
The frequency, scope, and depth of the inspection of bridges generally depend on several parameters such as age, traffic characteristics, state of maintenance, fatigue-prone details, weight limit posting level, and known deficiencies. Bridge owners may establish the specific frequency of inspection based on the above factors.
49.3.3 Tools for Inspection
In order to perform an accurate and comprehensive inspection, proper tools must be available. As
a minimum, an inspector needs to have a 2-m (6-ft) pocket tape, a 30-m (100-ft) tape, a chipping hammer, scrapers, flat-bladed screwdriver, pocketknife, wire brush, field marking crayon, flashlight, plumb bob, binoculars, thermometer, tool belt with tool pouch, and a carrying bag. Other useful tools are a shovel, vernier or jaw-type calipers, lighted magnifying glass, inspection mirrors, dye penetrant, 1-m (4-ft) carpenterrsquo;s level, optical crack gauge, paint film gauge, and first-aid kits. Additional special inspection tools are survey, nondestructive testing, and underwater inspection equipment.
Inspection of a bridge prompts several unique challenges to bridge inspectors. One of the challenges to inspectors is the accessibility of bridge components. Most smaller bridges can be accessed from below without great effort, but larger bridges need the assistance of accessing equipment and vehicles. Common access equipment are ladders, rigging, boats or barges, floats, and scaffolds. Common access vehicles are manlifts, snoopers, aerial buckets, and tr
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