Chapter 8: Bridge Records

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Section 1: Definition of Terms

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Bridge Record Terms

A partial list of definitions related to bridge inspection is given in the AASHTO Manual for Bridge Evaluation.1 The same AASHTO definitions and specific additional terms are also used in various other chapters of this manual. The following discussion of Bridge Records includes some of the additional specific terms.

Bridge
A structure, including supports, erected over a depression or an obstruction, such as water, a highway, or a railway; having a roadway or track for carrying traffic or other moving loads; and having an opening measured along the center of the roadway of more than 20 feet between faces of abutments, spring lines of arches, or extreme ends of the openings for multiple box culverts or multiple pipes that are 60 inches or more in diameter and that have a clear distance between openings of less than half of the smallest pipe diameter.
Bridge Folder
Until recently the file for each bridge maintained by the District Bridge Inspection Office was a hard copy record of all inventory and inspection documentation for a bridge. With data now being submitted directly to PonTex, all data is recorded and held in electronic format and the bridge folder is now an archive of historical bridge information.
National Bridge Inventory Number
The unique 15-digit number assigned to any structure meeting the definition of a bridge. The number includes the 2-digit District Number, 3-digit County Number, a 1 digit fixed zero, the 4-digit Control Number, the 2-digit Section Number, and the 3-digit Permanent Structure Number. The Transportation Planning and Programming Division (TPP) assigns the county road and city street index numbers, which begin with a letter instead of number. This off-system index number uses the same 6 digits assigned to Control and Section for on-system highways. The Permanent Structure Number for off-system bridges is assigned by the district.
Bridge Inventory File
The electronic data in TxDOT's bridge inventory, inspection, and appraisal ratings for each bridge on a public roadway in Texas. The data formerly were entered from a completed coding form. Data now is entered through PonTex either using the TxDOT network or the internet. The instructions for the Coding Guide describe the step-by-step data entry requirements.
Bridge Record
The over-all collection of data including the Bridge Folder with completed forms, printout of coded electronic data, sketches, cross sections, photos, etc. It also includes the Bridge Inventory File stored on electronic media. The Bridge Record also includes the bridge plans, if available, copies of which may be in the Bridge Folder or in TxDOT's accessible file systems. Some of the bridge plans may also be available on electronic media in the form of computer-aided drafting (CAD) drawings. Historically this information was stored in hard copy format, but now the Bridge Record is being stored in the PonTex bridge inventory and management system.
Control-Section-Job (CSJ) Numbers
These are numbers assigned to all on-system public highways in Texas. The Control Number is assigned to a stretch of highway that often breaks at a county line or a major highway intersection, river or stream, but can also break at any convenient location. The Section Number is a number within a specific Control and is usually assigned sequentially from the beginning of the Control. An average length for most Sections is about 4 to 5 miles but can be less than a mile or 15 to 20 miles. The Job Number is the sequential number for any type of construction project (bridge, paving, etc) that may have ever occurred on that Section of highway. Job numbers within a Section can be well over 100. All off-system highways are assigned similar sequential numbers by the district within each county. Refer to Items 8.4 and 8.5 of the "Instructions for Coding Guide" for more information.
Culverts
Multiple-barrel box culverts or multiple-pipe culverts are sometimes classed as bridges and a complete Bridge Record is made. The 1994 AASHTO Manual2 defines a bridge as any structure carrying traffic (highway or railroad) having an opening measured along the centerline of the roadway of more than 20 feet between the limits of the extreme openings of abutments, arches, or multiple boxes. This definition has created the anomaly in some cases where, for instance, three 6-ft multiple box culverts installed at more than about a 15-degree skew to the roadway must have a Bridge Record. If the same three box culverts are installed perpendicular to the roadway, they have no Bridge Record. The AASHTO definition continues for multiple-pipe culverts by stating that they may be classed as bridges provided the distance between individual pipes (the fill) is less than half the adjacent pipe diameter. In addition to this provision, TxDOT also requires pipe culverts to be at least 60" in diameter to be considered as a multiple-pipe bridge class installation.
Elemental Data
Identifies the various parts of the bridge (Elements), the material type and measures or estimates the condition of that element through specific predefined condition states. Additional information is available in "Elements" Field Inspection and Coding Manual.
Collecting data in this manner helps to better quantify the condition of a bridge or a system of bridges. By characterizing part of a bridge by the type of member and its material the following types of analysis can more easily be performed: 1) prediction of deterioration, 2) prediction of costs for repair, rehabilitation or replacement, 3) identification of alternative programs based on level of service or other criteria, 4) optimization of expenditure based on user and agency costs, 5) budget forecasts, and 6) development of programs for improvements.
Engineer
The qualified, Texas-licensed, Professional Engineer having responsibility for ensuring the accuracy of the information contained in the Bridge Record. A pre-qualified consulting firm engaged by TxDOT to perform routine bridge inspections is also considered in the following discussions to be covered by the term Engineer. Inspections done by TxDOT staff must also have a qualified, Texas-licensed, Professional Engineer responsible for the Bridge Records. The same basic procedures are used by TxDOT personnel as are required for consulting firms.
Forms
Specific forms such as the Bridge Inspection Record, or the Bridge Inventory Record, or the Follow-up Action Worksheet forms may be developed as needed for specific types of data or classes of structures.
NBI Sheet
A printed copy with abbreviated names of the numerical data in the electronic Bridge Inspection File. NBI stands for National Bridge Inventory, which must include all the information required by the FHWA. Texas captures additional information exceeding that required by the NBI. However, in Texas the sheet is still commonly called the "NBI Sheet." The FHWA data requirements are described in a report titled Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation's Bridges 3.”
Permanent Structure Number (PSN)
A unique three-digit number assigned to any structure meeting the definition of a bridge. It is part of the 15-digit National Bridge Inventory Number. PSNs are assigned by Control-Section Segments in ascending order as the bridges are built and are not necessarily in sequence along the Control-Section Segment. An on-system bridge replaced by a new bridge at the same location will have a new number assigned. A widened or reconstructed bridge will retain the same number. Districts assign similar unique numbers to off-system bridges. An off-system bridge replaced by a new bridge will retain the same PSN. A bridge with a longitudinal open joint in the middle will have two PSNs, even if the superstructures share a common substructure element4.
Bridge Division.
Route Over or Under
A bridge at intersecting highways is defined as an underpass or overpass based on the inventory hierarchy of the two routes. This description is used where required on all forms, plans, etc. The hierarchy of Texas highways is: Interstate, US, SH, State Loops or Spurs, FM/RM, County Roads (CR), and Business Routes (BR). The lower route number takes precedence if the highways are of equal hierarchy. Examples are:
  • IH 30 over IH 35 - IH 30 Overpass at IH 35
  • IH 35 over IH 30 - IH 30 Underpass at IH 35
  • FM 1234 over US 290 - US 290 Underpass at FM 1234
  • CR 18 under US 183 - US 183 Overpass at County Road 18
  • IH 20 Business under RM 456 - RM 456 Overpass at IH 20 Business
Signing and Sealing
The Engineer must affix a seal containing the Engineer's license number, sign, and date many of the documents prepared for a bridge inspection. The Signing and Sealing requirements are in conformance with the Texas Engineering Practice Act and TxDOT policy.56 Date the seal on the day it was affixed to the document.
Work Authorization
Authorization issued by TxDOT to a consultant (Engineer) to perform inspections of bridge structures in various counties and districts in Texas. The Work Authorization is normally issued for a specific period of time with a commencement and ending date specified. Consultants under contract to TxDOT must pre-qualify by demonstrating that they are competent to inspect Texas bridges.

1. AASHTO Manual for Bridge Evaluation, Second Edition, 2011.

2. Manual for Condition Evaluation of Bridges, AASHTO, 1994

3. Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation’s Bridges, FHWA, 1995.

4. “Permanent Structure Numbers,” Administrative Circular 20-74, TxDOT, February 1974.

5. Occupations Code, Section 1001.401. Texas Administrative Code, Title 22, Section 131.166.

6. Procedures for Sealing Engineering Documents, Stand-alone Manual Notice 97-2, TxDOT, March 1997

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