Long-Term Bridge Performance (LTBP) Program Protocols, Version 1

Chapter 2. Organization and Designations of the LTBP Program Protocols

The LTBP Program protocols are organized into a hierarchy based on the chronology of a data collection effort for a single bridge: before a field visit, during a field visit, and after a field visit. This simple chronology was selected to make finding the required protocols intuitive for end users. The first three levels of the proposed hierarchy are shown in figure 1.

Figure 1. Illustration. LTBP Program Protocol Hierarchy.

The individual protocols that fall under each of the third-level groups are not shown for brevity. Following are brief descriptions of the primary and secondary levels and the kinds of protocols contained in the various groups.

This first version of the LTBP Protocols report includes some or all of the protocols intended for some of the groups shown in figure 1. Subsequent versions of the report will include protocols added, moved, or deleted to meet the needs of the LTBP Program.

PREVISIT PROTOCOLS (PRE)

The PRE protocols focus on preparations and actions that occur prior to collecting data at the bridge. This group includes protocols that provide guidance on bridge selection; obtaining existing bridge documentation from State departments of transportation and extracting the data; and preliminary planning and logistics for facilitating a safe and successful field data collection effort. The PRE protocols, such as those for traffic safety and personal safety equipment, are typical across multiple types of data collection. In other cases, information that varies between protocols, but is a common requirement, is collated in the previsit protocols. An example would be any personnel certification or experience requirements collected into a single protocol to facilitate updates in the future.

Sampling and Selection (SS)

The FHWA team is responsible for bridge selection and sampling, so these protocols are included as information resources for the persons responsible for data collection. This permits the team to understand the full process and ensures that, should the program expand and more bridges need to be selected, the knowledge is preserved, and the methods used for bridge selection can be repeated exactly.

Existing Documentation (ED)

The ED protocols address the information to be collected from bridge owners, dating back to the design and construction of the bridge, including data related to inspections, maintenance, and cost (when available). The ED protocol group also includes protocols detailing the execution of legacy data mining for specific performance issues—that is, identifying how the data can be used both before and after field testing to draw conclusions about a structure’s performance and the factors that have influenced it. Field data collection will not occur for all bridges selected for participation in the LTBP Program, and data collection efforts will stop after legacy data mining is completed.

Equipment (EQ)

The EQ protocols cover equipment related to structural testing. Generally speaking, the EQ protocols include sensors and data acquisition systems, which are described in an overview protocol. There are specific protocols related to each type of structural testing, including truck testing, long-term monitoring, and vibration testing. The primary sensor types are described based on the measurement they are designed to collect, as opposed to specific sensor brands or types. The information in the EQ protocols is general in nature, and the information is not specific to brand or manufacturer.

Preliminary Planning and Logistics (PL)

The protocols in this group cover all aspects of preparation for a field data collection effort, from personnel safety to the processes for maintenance and protection of traffic and site-specific requirements. The PL protocols address equipment-related issues such as sensor calibration and maintenance requirements. For each data collection type, a general test planning protocol is included that covers test-specific requirements, general field requirements, and heuristic-based advice needed to achieve successful field data collection. Protocols providing guidance on developing and using representative models are also included.

FIELD VISIT PROTOCOLS (FLD)

The FLD protocols focus on the collection of research-quality data in a consistent manner to facilitate comparative analysis across structures and with time. While the protocols in this report address collecting both data and metadata for visual inspection, material testing, NDE testing, logistics and safety, and data storage, future versions of the LTBP Program’s protocols report will cover live load testing, short- and long-term monitoring, weigh-in-motion techniques, instrumentation, and importing the data into the LTBP Bridge Portal.

Onsite Pretest Activities (OP)

This group of protocols provides guidance on segmenting, identifying, and labeling the various elements of a bridge so that the recorded findings of the field assessment and testing activities may be tied to specific elements and locations on the bridge. A convention for creating unique alphanumeric element identifiers for the various parts of the bridge is prescribed. In order to allow for the precise size and location of findings, a 2- by 2-ft grid with a defined origin is defined on the deck surface and local origins are described for the common elements of the bridge, such as girders, pier caps, and abutments.

Field Data Collection (DC)

The DC protocols make up the main portion of the protocols and cover data collection at the bridge. Methods of data collection included in this report are visual inspection, material sampling, and manual NDE testing. These protocols provide clear, step-by-step instructions for data collection, and comprehensive references for all standards cited in the protocols. The DC protocol group also includes protocols for documenting weather and traffic information during actual data collection, image capture (both still photography and videos), and names of the evaluators.

Data Storage (DS)

The DS protocols address the proper storage of raw data immediately after collection to ensure no repeat field efforts are required and that no data are lost. The critical timeframe covered by these data storage protocols spans between data collection and uploading to the LTBP Bridge Portal. The DS protocols also make provisions for loss of data by storing a second copy of the data at a remote location.

POSTVISIT PROTOCOLS (PST)

Protocols in the PST group focus on actions taken after the data are collected at the bridge and how the collected data are used to draw conclusions. These protocols include immediate data reduction, data validation, data interpretation, fusion and visualization of disparate of data, reporting data, and archiving integrated data into the LTBP Bridge Portal. PST protocols will be published in a later version of this report.

Data Reduction and Processing (DR)

Raw data, particularly quantitative data from structural testing or NDE, generally require error screening, postprocessing, and data reduction. Analogous protocols for material sampling and visual inspection are included as well. Consistency between data reduction and processing methods is critical to ensure comparisons of information from different modalities of data collection are reliable.

Data Interpretation (DI)

Data can be interpreted in many ways, including directly, comparatively, and through a model. The DI protocols identify the data interpretation methods and provide the steps to be taken to evaluate and interpret the data and metadata. The DI protocols also identify the relationships between data interpretation methods.

Archiving and Reporting (AR)

The AR group of protocols focuses on consistency in reporting results as well as formatting data and metadata for inclusion in the Bridge Portal. Future protocols will address archiving the data and metadata.

PROTOCOL NAMING CONVENTION

The following LTBP Program protocol naming convention was adopted to allow easy identification and future expansion:

XXX-YY-ZZ[Z]-###

where:

XXX = Stage of data collection (PRE, FLD, or PST).

YY = Subcategory under the stage describing the research activity or focus (e.g., ED = Existing Documentation).

ZZ[Z] = Identifier to distinguish further between data collection methods; note some protocols may have a third letter identifier.

### = Number assigned sequentially from 001 to 999.