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1  The ride quality of the highway system, which includes pavements and bridges, is impor- tant to the traveling public. State Departments of Transportation (DOTs) are required to perform biennial inspection of highway bridges and submit data annually to the Fed- eral Highway Administration (FHWA) to be included into the National Bridge Inventory (NBI). The condition of the bridge deck is rated in this evaluation, but the ride quality of the bridge deck is not a factor that is considered during the rating. State DOTs are required to submit the roughness data of selected highway segments to the FHWA Highway Perfor- mance Monitoring System (HPMS). Roughness data on bridges can also be submitted to the HPMS if desired by the state DOT, but the HPMS does not separately report the roughness of bridges. Therefore, there is no national database that records the roughness of bridges in the United States, although this information is available for pavements. Studies performed in Illinois, Ohio, and Virginia have shown that the bridges provide a lower ride quality when compared to pavements. A study performed on the Interstate system in Ohio showed that bridges are two and a half times rougher than pavements. The objectives of this synthesis were to document the procedures used by state DOTs to evaluate the smoothness of concrete bridge decks when constructed, procedures used to keep track of the roughness of concrete bridge decks over time, and procedures used to maintain the smoothness of concrete bridge decks over their life. A survey was sent to the DOTs in the 50 states and the District of Columbia to gather information related to the study objectives. Thirty-nine state DOTs responded to the survey, which represents a response rate of 76%. A variety of methods are used by state DOTs to evaluate the smoothness of newly con- structed concrete bridge decks. The methods used by the DOTs include the following: ⢠Smoothness not evaluated (two state DOTs, 5% of respondents). ⢠Using only a straightedge (17 state DOTs, 43% of respondents). ⢠Based on a rolling straightedge (six state DOTs, 15% of respondents). ⢠Based on a straightedge or a rolling straightedge (one state DOT, 2% of respondents). ⢠Based on International Roughness Index (IRI) (six state DOTs, 15% of respondents). ⢠Based on profilograph measurements (eight state DOTs, 20% of respondents). Some DOTs that have IRI-based or profilograph-based criteria also have a straightedge- based criterion. Ten state DOTs (26% of respondents) indicated they store the IRI of bridges in their pavement management system (PMS) or the bridge management system. None of the state DOTs that store the IRI data for bridges monitor the progression of roughness of their bridges. One state DOT that stores the IRI data for bridges indicated the decision tree for managing bridges triggers a treatment based on the roughness level of the bridge. S U M M A R Y Practices for Ensuring the Smoothness of Concrete Bridge Decks
2 Practices for Ensuring the Smoothness of Concrete Bridge Decks Four DOTs (10% of respondents) indicated they have a schedule for performing main- tenance activities on bridges that affect ride quality, with 32 DOTs (82% of respondents) indicating they do not have a schedule, and three DOTs (8% of respondents) indicating it is unknown if there is a schedule. Four DOTs (10% of respondents) indicated dedicated funding is provided annually to address smoothness-related issues on bridges, with 24 DOTs (62% of respondents) indicat- ing no such funding is provided, and 11 DOTs (28% of respondents) indicated it is unknown if dedicated funding is provided. The survey indicated the following maintenance or rehabilitation activities are performed on bridge decks to maintain smoothness: ⢠Repairing expansion joints (27% of respondents). ⢠Repairing distress in approach slabs (23% of respondents). ⢠Placing an asphalt overlay (18% of respondents). ⢠Placing a polymer overlay (17% of respondents). ⢠Placing a concrete overlay (15% of respondents). Several respondents indicated the maintenance and rehabilitation activities on the bridge deck are not specifically performed to maintain smoothness, but are performed for bridge preservation. As a part of this study, interviews were conducted with six state DOTs (those in Florida, Mississippi, Nevada, New Jersey, Ohio, and Utah) to obtain detailed information about the smoothness specifications used by these state DOTs for newly constructed concrete bridges. Three of these DOTs (Nevada DOT, Ohio DOT, and Utah DOT) use IRI-based specifications, two of the DOTs (Florida DOT and Mississippi DOT) use specifications based on profilograph measurements, and the other DOT (New Jersey DOT) uses a rolling straightedge-based specification using a walking profiler as the equipment to collect data. The information obtained from the interviews is documented under case examples in this synthesis. The following topics were identified as areas where there are gaps in knowledge, which research could be conducted to fill: ⢠Roughness of in-service concrete bridge decks: There is a lack of information about the roughness level of in-service concrete bridges in the United States, as there is no database that has this information. ⢠Localized roughness level at pavement-bridge interface: There is a lack of information about the level of localized roughness that is present at the pavement-bridge interface on in-service highways. ⢠Smoothness level that can be achieved on newly constructed concrete bridge decks: There is a lack of information about the smoothness level that can be achieved for newly con- structed concrete bridge decks.
