Practices for Ensuring the Smoothness of Concrete Bridge Decks (2022)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

47   The ride quality of the highway system, which includes pavements and bridges, is important to the traveling public. 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 literature review was performed to review information related to bridge roughness. There- after, a survey was sent to DOTs in the 50 states and the District of Columbia to gather infor- mation related to the study objectives. Thirty-nine state DOTs responded to the survey, which represents a response rate of 76%. Thereafter, interviews were conducted with six state DOTs to obtain detailed information about the smoothness specification used in each state to ensure the smoothness of newly constructed concrete bridge decks. Main Findings Literature Review State DOTs are required to perform biennial inspection of highway bridges and submit data annually to the FHWA in a suitable format to be entered into the NBI database. One item that must be rated is the condition of the bridge deck. However, the ride quality of the bridge deck is not considered when rating the bridge deck and is not a data element that is required to be submitted to the FHWA. State DOTs are required to submit the roughness data of selected high- way segments to the HPMS. Roughness data on bridges can also be submitted to the HPMS if desired by the state DOT. However, 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 Ohio, Illinois, and Virginia have shown that the bridges provide a lower ride quality when compared to pave- ments. A study performed on the Interstate system in Ohio showed that bridges are two and a half times rougher than pavements. State of the Practice A variety of methods are used by state DOTs to evaluate the smoothness of newly constructed concrete bridge decks. The methods used by the DOTs include the following: • Based on 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 IRI (six state DOTs, 15% of respondents). • Based on profilograph measurements (eight state DOTs, 20% of respondents). C H A P T E R 5 Summary of Findings

48 Practices for Ensuring the Smoothness of Concrete Bridge Decks Two state DOTs (5% of respondents) indicated they do not have smoothness requirements for concrete bridge decks. One of these DOTs indicated that the reason they do not have such a requirement is because concrete bridges in the state are overlaid with AC. For the DOTs that use a straightedge to evaluate the smoothness, the most common method is to use a 10 ft. straightedge that is placed in the travel direction and to require the deviation from the bottom of the straightedge to the top of the pavement to be less than ⅛ in. For the six state DOTs that have a specification for smoothness based on a rolling straight- edge, a variety of methods are used to obtain the rolling straightedge measurements. Four DOTs use actual rolling straightedges, one DOT collects data using an inertial profiler and performs a rolling straightedge simulation on the collected data, and the other DOT collects data using a walking profiler and performs a rolling straightedge simulation on the collected data. The actual rolling straightedge or the rolling straightedge that is used for the simulation is 10 ft. long in all cases, while the maximum permissible deviation at the center wheel was ⅛ in., except for one DOT that uses a value of ¼ in. Six state DOTs use an IRI-based specification to evaluate smoothness. Four of these DOTs have criteria that are based on MIRI and localized roughness: two DOTs have localized rough- ness criterion based on IRI; one DOT uses a straightedge to detect surface irregularities; and one DOT uses a profilograph to detect surface irregularities. Two of the DOTs do not have a MIRI- based criterion for smoothness and only have a localized IRI-based criterion. Eight state DOTs have a smoothness specification based on profilograph measurements. Four of these DOTs require an actual profilograph that is 25-ft. long to be used for measurements, while one DOT uses a modified profilograph that is 12 ft. long. Two state DOTs use a profilograph simu- lation performed on data collected with an inertial profiler to obtain the profilograph measure- ments, while one state DOT allows the use of an actual profilograph or a profilograph simulation on the data collected by an inertial profiler to obtain the profilograph measurements. Of these eight state DOTs, seven DOTs have a PI-based criterion as well as a bump criterion to evaluate smooth- ness, while one DOT only has a PI-based criterion. For computing the PI, three of the state DOTs use a zero-blanking band, while the others use either a 0.1- or a 0.2-in. blanking band. The limits for bumps used by the state DOTs were variable with values ranging from 0.15 to 0.5 in. Ten state DOTs (26% of respondents) indicated they store the IRI of bridges in the PMS or the BMS. None of the state DOTs that store the IRI data for bridges monitor the progression of roughness of their bridges. Of the state DOTs that store the IRI data, one state DOT indicated the decision tree for managing bridges triggers a treatment based on the roughness level of a bridge deck. Four DOTs (10% of respondents) indicated they have a schedule for performing maintenance 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) indicating no such fund- ing is provided, and 11 DOTs (28% of respondents) indicating 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 responses). • Repairing distress in approach slabs (23% of responses).

Summary of Findings 49   • Placing an AC overlay (18% of responses). • Placing a polymer overlay (17% of responses). • Placing a concrete overlay (15% of responses). Some of the respondents indicated the maintenance and rehabilitation activities are not spe- cifically performed to maintain smoothness, but rather are performed for bridge preservation. Case Examples 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 an IRI-based specification, two of the DOTs (Florida DOT and Mississippi DOT) use a specification based on profilograph measurements, and the other DOT (New Jersey DOT) uses a rolling straightedge-based specification, where a rolling straightedge simulation is performed on the data collected with a walking profiler. Although the Nevada, Ohio, and Utah DOTs all use an IRI-based smoothness specification, there were differences in the way the IRI was used in these specifications. Utah DOT uses a specification based on an allowable MIRI value and a localized roughness criterion based on IRI, while Nevada DOT’s specification only uses a localized roughness criterion based on IRI. Ohio DOT’s specification is also based on localized IRI but uses a histogram method to classify localized roughness into bins, and uses the localized IRI distribution to determine payment (i.e., full payment, positive pay adjustment, and negative pay adjustment). Gaps in Knowledge and Suggestions for Future Research The following are gaps in knowledge in the area of concrete bridge smoothness where future research is suggested: • Roughness of in-service concrete bridge decks: There is a lack of information about the rough- ness level of in-service concrete bridge decks in the U.S., as there is no database that has this information. A study is needed to obtain information about the roughness level of in-service concrete bridge decks in the United States. It may be possible to obtain some information on this subject by analyzing the IRI data submitted to the HPMS that is coded as a bridge deck. • Localized roughness level at the pavement-bridge interface: The pavement-bridge interface is an area where a high roughness level may be present. The roughness level at this location increases over time because of differential settlement between the abutment that supports the bridge and the embankment that supports the pavement. There is a lack of information about the level of localized roughness that is present at the pavement-bridge interface on in-service highways. A study is needed to gather information about the level of localized roughness that is present at the pavement-bridge interface on in-service highways. This information will be useful to gain an understanding of the ride quality discomfort experienced by road users because of localized roughness at the pavement-bridge interface. • 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 a newly con- structed concrete bridge deck. Some of the state DOTs that have adopted IRI-based smooth- ness specifications may have this information. A study is needed to gather information on this topic.