Highway and Rail Transit Tunnel Inspection Manual
Chapter 5: Inspection Documentation
A. Field Data
1. Tunnel Structure
The inspection should be thoroughly and accurately documented. For the tunnel structure, the documentation of severe defects should include a sketch showing the location and size of the defect and a verbal description of the defect. All severe defects should be photographed; however, a representative photo of minor or moderate defects will be sufficient. All defects should be described but sketches need only to be made for severe defects.
The sketches of the defect can be made on forms developed during the mobilization phase or on computer screens, as appropriate. These forms should show the necessary plan and elevation views of the structural element to which they pertain. Blank forms should also be provided for additional sketches where deemed necessary by the inspectors. All defects should be located on sketches or the computer screen by dimensioning their location in reference to the beginning or end of the element. Each defect should be dimensioned showing its length, width, and depth (if applicable).
For consistency in documenting the inspection findings, each inspector should use the following system both to describe the defect and to classify them as minor, moderate or severe:
|Description of Defect||Classification|
|Crack - CR||1 - Minor|
|Scaling - SC||2 - Moderate|
|Spall - SP||3 - Severe|
|Staining - ST|
|Exposed Reinforcement - E|
|Corrosion - C|
|Honeycomb - H|
|Patch Failure - PF|
|Hollow Area - HA|
|Debris - D|
|Buckle - B|
|Efflorescence - EF|
|Leakage - LK|
|Check - CK|
|Rot - RT|
|Fire Damage - FD|
|Paint Deterioration - PD|
For example, a moderate spall should be labeled as SP2, a severe crack as CR3, etc. This designation should be placed on the sketch and connected to the defect by means of a leader to clearly identify the defect. Samples of completed field sketches for tunnel segments, developed using both a tablet PC data collector and a pre-printed form, are shown in Figures 5.1 and 5.2, respectively. In addition, Figure 5.03 shows an example of a defect location form for an auxiliary space that was completed using a pre-printed form. Upon completion of each section or miscellaneous appurtenance being inspected, a summary rating sheet as shown in Chapter 3, Section D, Part 3, should be completed as a record of the inspection.
Before placing any other information on a form, always complete the spaces at the top of the form identifying the structural element. This will eliminate any confusion when numerous structural elements are completed. A 35 mm or digital camera should be used to take photographs during the inspection. Each inspector will keep a log of all photographs taken. This log should identify the element being inspected, a description of the photograph, the counter number, and the roll number (if appropriate). Examples of photo log sheets and sketch sheets are shown in Chapter 3, Section D, Part 3.
2. Track Structure
TSS Part 213, Subpart F, Section 213.241 - Inspection Records requires that rail transit owners are to keep records of each inspection performed. This section identifies when the records are to be completed and the method of record retention - either paper or electronically. Undoubtedly, rail transit owners already have developed in-house forms for these inspections so none will be presented herein. It is suggested that these procedures be followed by all rail transit owners, even if it requires changes to their current documentation procedures.
3. Specialized Testing Reports
To inspect certain mechanical, electrical, and other associated track systems requires the use of specialized testing agencies and equipment. All such reports derived from these special testings shall become a part of the documentation of the particular inspection period.
Figure 5.01 - Tunnel Inspection Form (Tablet PC Data Collector)
Figure 5.02 - Tunnel Inspection Form (Pre-Printed Form)
Figure 5.03 - Portal Inspection Form (Pre-Printed Form)
B. Repair Priority Definitions
When summarizing inspection data and making recommendations for future repairs it is necessary to define categories that prioritize the repairs that are to be performed. These recommendations can be included in an inspection report format and/or entered into a structural database for scheduling repairs/rehabilitation and for historical purposes. The following repair classifications are suggested:
As discussed in Chapter 4, Section A, Part 3, a defect requires this designation if it requires "immediate" action including possible closure of the structure or areas affected for safety reasons or from system operation until interim remedial measures can be implemented.
Refers to conditions for which further investigations, design, and implementation of interim or long-term repairs should be undertaken on a priority basis, i.e., taking precedence over all other scheduled work. These repairs will improve the durability and aesthetics of the structure or element and will reduce future maintenance costs. Elements that do not comply with code requirements are also in these classifications. Such repairs should be scheduled for completion within two years.
Refers to conditions requiring further investigation or remedial work that can be undertaken as part of a scheduled maintenance program, other scheduled project, or routine facility maintenance depending on the action required. All items identified in the preventive maintenance program should also be incorporated in this category. Such items should be scheduled for completion after two years.
Upon completion of all elements of the inspection, the tunnel owner should require a formal report be developed that summarizes the findings from each element that was inspected. This report will be used to educate the tunnel owner of deficiencies within the tunnel and enable him/her to schedule repairs and allocate sufficient funding.
The report should be supplemented with a computerized database that includes the rating information on structural elements. This database will permit the tunnel owner to query and develop reports as necessary for any inspected element in the tunnel. Below is a suggested outline for the report along with a description of the contents to be included in each section.
- Letter of Transmittal - Formal identification of report and introduction to the recipient.
- Table of Contents - Self-explanatory.
- List of Tables - Used to identify the title and location of any tables that were used to summarize the inspection findings.
- List of Figures and Drawings - Used to identify the title and location of any figures or drawings that were used to describe the inspection.
- List of Photographs - Used to identify the title and location of any photographs that were taken to document the inspection findings.
- Executive Summary - Provide a concise summary of the inspection, findings, and recommended repairs.
- General Description - Provide a general description of the tunnel or tunnels that were inspected. This information could include the location of the tunnel(s), age, general geometry, and any other pertinent descriptive information.
- Inspection Procedures - The procedures used to perform the inspection of the various tunnel elements below should be explained and illustrated if necessary. Recognition should also be given to any special testing agencies that were used to complete the inspection.
- Track, Third Rail, Catenary, Signals, and Communications.
- Inspection Findings - A detailed description of the results of the inspection should be included for the various tunnel elements below.
- Civil/Structural - For civil/structural elements, the report should contain descriptions of the various deficiencies found, their locations and their severity. Any special testing, such as concrete strength, freeze-thaw analysis, or petrographic analysis should be included with the findings.
- Mechanical - For the mechanical inspections, the general condition and operation of all equipment should be described and deficiencies noted. Specialized testing required to effectively determine the operational condition of the equipment, such as vibration testing and oil analyses, shall be included for historical purposes.
- Electrical - For the electrical inspections, the general condition and operation of all equipment should be described and deficiencies noted. Specialized testing required to effectively determine the operational condition of the equipment, such as power distribution and emergency power, shall be included for historical purposes. In addition, measurement of light levels versus that recommended should be provided to the owner. Where testing agencies performed remedial work along with the testing, such as tightening loose wires, etc., it should be included.
- Track, Third Rail, Catenary, Signals, and Communications - For the inspection of track, traction power, signals, and communications, the inspectors shall discuss the overall findings and provide copies of specialized testing results.
- Recommendations - This section will include actual recommendations for repair/ rehabilitation of the tunnel components that were found to be deficient or that did not meet current code requirements. The owner may desire that an estimate of cost be made by the inspectors to correct the defective elements. If substantial rehabilitation is required, the owner may request a life-cycle cost comparison be made comparing repair options in the short-term versus long-term rehabilitation. The repair/rehabilitation should be broken down for each of the main tunnel systems into the different categories listed below, which were defined in the previous section.
- Appendices - The appendices should be used to display detailed and extensive inspection summaries that were too lengthy to include in the body of the report, such as structural panel ratings and lighting illuminance levels. Also, reports provided by special testing agencies should be included in their entirety. Other items that should be included in the appendices are special permits or qualifications that were needed to perform the inspections. An example of this would be confined space entry permits, qualifications, and procedures needed for entering certain areas of a tunnel, such as the air plenums above or below the tunnel space.
This summary report along with the testing results will provide an historical document recording the condition of the tunnel and its inherent systems for the period indicated. This document can be compared to documents from future inspections for tunnel owners to evaluate the overall long-term condition of various tunnel elements.