Guide for Conducting Forensic Investigations of Highway Pavements (2013)

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13 This chapter follows the suggested agency forensic investi- gation protocol and staffing discussed in Appendix A. It cov- ers preparing and evaluating investigation requests, deciding to proceed or not to proceed with an investigation based on the request, initiating a forensic investigation, undertaking a background study, identifying issues of interest and prepar- ing objectives to address them, collecting relevant informa- tion, determining whether a forensic evaluation is justified, preparing a preliminary investigation report, and recording the decision to proceed or not to proceed with a forensic investigation. 3.1 Preparing a Forensic Investigation Request A forensic investigation begins with a formal request (example Form #1 in Appendix C) from an agency employee or from an organization undertaking research or other work on behalf of the agency (e.g., a university research center or an appointed consultant) to the forensic investigation coordinator (discussed in Appendix A). The requestor: 1. Completes the formal request that includes contact details, location of the issues to be investigated, the rea- sons for the investigation (why the investigation needs to be carried out and how the results will be used), a summary of work already undertaken that prompted the request for the investigation, details about the proj- ect that the issue is part of, and a justification for urgency. Preliminary details about the project may include, but are not limited to: – Pavement structure and surface type. – Date opened to traffic. – Suspected source of problem. – Length of the project or proportion of job affected. 2. Submits the request to the agency forensic investigation coordinator. 3.2 Evaluating a Forensic Investigation Request On receipt of the request, the forensic investigation coordinator: 1. Acknowledges receipt of the request form. 2. Opens a project file and starts a budgeting/cost-tracking spreadsheet and/or assigns a charge number for team members to book time to during the investigation. 3. Issues an investigation number. This number should include the year plus a consecutive number as a mini- mum (e.g., 2011/01), but can include other agency specific data that will facilitate later retrieval (e.g., district, route number and post-mile, pavement type, investigation type code, etc.). 4. Evaluates the request and determines whether the request should be supported. This may require discussion with the requestor to fully understand the request intent and issues to be investigated. Reasons to consider a request inappropriate include: – The problem is identical to one that has already been investigated or is currently being investigated. – The problem is clearly linked to a known construction deficiency (e.g., compaction requirements were not met and were not corrected at time of construction). – The issues can be clearly linked to normal pavement behavior/deterioration. – The issues can be linked directly to a known event (e.g., severe rutting linked to the issuance of an abnormal load permit). 5. Records whether the investigation should be supported or not on the request form and signs the form. C h a p t e r 3 Investigation Request and Preliminary Investigation

3.3 Record of Decision to Proceed or Not to Proceed with Investigation The record of decision is completed by signing the request form. The investigation coordinator notifies the investigation requestor of the decision. If the decision does not support proceeding with the investigation, the project file is closed. 3.4 Initiating a Forensic Investigation The investigation coordinator initiates a forensic investi- gation after the decision to proceed has been recorded. The investigation coordinator should then identify the investiga- tion director (discussed in Appendix A) and request permis- sion (and if necessary, funding) to proceed with a preliminary investigation. 3.5 Undertaking the Preliminary Investigation A preliminary investigation is undertaken to formulate the objectives, determine whether a forensic investigation is necessary to meet these objectives, and, if it is, the level of required investigation. The preliminary investigation is typi- cally undertaken by the forensic investigation coordinator and, if appropriate, the individual requesting the investiga- tion, and includes the following tasks: 1. Identify the issues that need to be considered/addressed. 2. Prepare objectives to address the identified issues. 3. Collect and review relevant information. 4. Determine whether a forensic investigation is justified. 5. Prepare a record of decision. 6. Identify an appropriate level of investigation. 7. Prepare a preliminary investigation report. 3.5.1 Identifying Relevant Issues and Objectives The first task in a forensic investigation is to understand the issues underlying the request for the investigation and then setting the objectives to address these issues. Examples of typical issues and related objectives include: • Issue: Premature pavement failure. – Example objectives: 77 Determine the causes of premature failure at site location. 77 Identify if the failure is likely to occur in other areas where it has not yet been observed. 77 Determine how the failure will be repaired. 77 Determine whether design and/or specifications should be changed to avoid recurrence. • Issue: Pavement performed much better than expected. – Example objectives: 77 Determine the reasons for exceptional performance at site location. 77 Determine whether design and/or specifications should be changed. • Issue: One pavement section performed differently than another. – Example objectives: 77 Determine the reasons for different pavement per- formance at site location. 77 Determine actions needed to obtain uniform perfor- mance. • Issue: Repair of the pavement failure under warranty. – Example objectives: 77 Determine the causes of pavement distress. 77 Determine how the distress should be repaired. 77 Determine compliance with warranty provisions. • Issue: Poor surface characteristics of the pavement. – Example objectives: 77 Determine whether the pavement functionality is influenced by material, construction, and/or maintenance-related factors. 77 Determine what corrective action needs to be taken, if any. 77 Determine whether specifications need to be changed. • Issue: Performance of experimental pavement sections. – Example objectives: 77 Compare the distresses between the control and experimental sections. 77 Determine whether or not the technology/method experimented with warrants implementation. 77 Determine whether or not design procedures and specifications need to be changed. 77 Collect data for developing/calibrating/refining per- formance models. The forensic investigation coordinator documents the issues to be addressed and the study objectives on an appro- priate form (example Form #2 in Appendix C.) 3.5.2 Collecting Relevant Information Relevant information needs to be collected to determine whether or not a forensic investigation is justified, and, if it is, to determine the level of investigation required and prepare a budget and plan for successful completion. This information typically includes the following: 14

15 tive of the traffic that led to/caused the issues being inves- tigated (e.g., a short period of overloaded trucks moving equipment to an industrial development). • Results of non-destructive or destructive testing already undertaken (e.g., GPR, FWD, profile, cores, etc.). All state highway agencies (SHAs) are required to collect longitu- dinal profile data on their network as part of the required Highway Performance Monitoring System (HPMS) report- ing of federal aid projects, and to submit the computed roughness in terms of the IRI. Most SHAs include longi- tudinal profile in their pavement management systems and have network-level IRI data readily available. • Other relevant information (e.g., information on accidents/ incidents, permits issued, etc.). • Information on underground services (e.g., gas lines, cables, pipelines, etc.) to determine whether they contributed to the issues being investigated, and whether they will influence the forensic investigation in any way. • An interview with the individuals requesting the investiga- tion to clarify reasons for the request and the issues to be investigated. • Interviews with agency and industry personnel (e.g., inspec- tors and contractors) familiar with the project/experiment to obtain their views regarding the issue under investigation. • Project information (e.g., location, extent) to identify the location and extent of the road section requiring investigation. • Structural design and as-built/constructed information to check if the issues being investigated can be explained by any apparent deviations from normal procedures. This includes a review of Quality Control/Quality Assurance (QC/QA) information for construction variables such as thickness and material type. • Materials design and as-built/constructed material prop- erties information to determine whether the issues being investigated can be explained by deviations from expected procedures (e.g., review of daily progress and QC/QA reports for information on equipment changes, weather impacts, construction variables such as compaction, open- ing times, opening temperatures, mix design formulae, admixtures, and strength, etc.). • Pavement management system data to examine past per- formance of the section, determine whether the issues is new, and/or determine whether past performance is a fac- tor in the issues being investigated. Note that while network-level data is useful for screening purposes, it often lacks the resolution required for detailed forensic investigations. • Maintenance records to obtain surface treatment and drainage maintenance histories. • Climate records to identify climatic events that may have contributed to the issues being investigated. The Road Weather Information System (RWIS) is a useful source for this. • Soil and geology maps to identify any subgrade soils or geologic anomalies. • Traffic data to identify changes in traffic patterns that may have contributed to the issues being investigated, includ- ing data on overload permits issued. Traffic data may be available from the agency weigh-in-motion database, or may be collected specifically for the investigation. Seasonal traffic variation (e.g., related to agriculture or to the use of studded tires/chains in winter) will need to be taken into consideration. Note that if traffic data is collected specifi- cally for a forensic investigation, it may not be representa- Warning Information on underground utilities may not be covered in design and as-built documentation. • Past forensic investigations to determine if similar issues have been investigated previously. • Existing soil information, which may be of value when iden- tifying any failure mechanisms from well below the surface of a pavement. National soils databases, provided by entities such as the National Resources Conservation Service, can provide relevant insight into existing conditions. • An internet search using selected keywords to determine whether similar experiences have been documented else- where. These searches can be particularly useful in identi- fying unexpected or unusual issues related to the observed performance. By scanning the collected data, the forensic investigation coordinator can determine whether any factors can be iden- tified that satisfactorily explain the issues being investigated. The forensic investigation coordinator also summarizes the findings on the Preliminary Investigation form (example Form #2 in Appendix C). 3.5.3 Determining Whether or Not a Forensic Evaluation is Justified The information collected in the previous task is used to determine whether a forensic investigation is justified by

16 • Agreement between the agency and the contractor in a warranty claim. • Ability to collect the data required for performance model- ing through routine methods. A forensic investigation is probably justified unless the issues can be readily explained. The forensic investigation coordi- nator should make a recommendation on whether or not to proceed with a forensic investigation. Where appropriate, the recommendation should include the benefits of undertaking the investigation or the consequences of not undertaking the investigation. The forensic investigation coordinator documents the rec- ommendation on an appropriate form (example Form #3 in Appendix C). 3.6 Preparing a Preliminary Investigation Report and Record of Decision The investigation coordinator prepares a preliminary inves- tigation report for record purposes consisting of a cover sheet (example Form #4 in Appendix C), the investigation request (example Form #1 in Appendix C), the preliminary investiga- tion summary (example Form #2 in Appendix C), and the sug- gested record of decision (example Form #3 in Appendix C). The forensic investigation coordinator then: 1. Obtains approval from the investigation director for the decision to proceed/not to proceed with a more detailed forensic investigation. 2. Records the decision and reasons for it in the project file (example Form #3 in Appendix C). 3. Notifies the requestor of the decision. considering the typical reasons for undertaking an investiga- tion, such as: • Poor performance, premature distress, and/or premature failure that can be linked to: – Inappropriate design (i.e., under design); – Deviations from accepted construction practice that do not directly affect standard QC/QA test results (e.g., stabilizer spreading and mixing procedures or pre-pulverization techniques on full-depth recycling projects that result in a different to expected grading); – Quality control/quality assurance issues (e.g., materials and construction deviations from specifications); – Significantly higher than expected traffic; – Overloading; – A specific event (e.g., rutting associated with an over- load permit, rutting or cracking related to extreme tem- peratures, deformation associated with flooding, etc.); – Changes in drainage (blocked, installed) or other hydrau- lic conditions (change in irrigation practice nearby, change in shoulder condition); and/or – Maintenance actions that may have affected materials or structure (e.g., joint sealing or repair, slab jacking, sprayed asphalt treatments that may soften or darken the asphalt near the surface, sanding, etc.). • Exceptionally good performance attributed to: – Inappropriate design (i.e., over-design); – Quality control/quality assurance issues (e.g., exceptional materials and construction quality in comparison to those specified); and/or – Significantly lower than expected traffic. • Consensus among agency practitioners on the causes of observed pavement performance.