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

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39   Overview Interviews were conducted with personnel from six state DOTs to obtain further informa- tion on the specification used by these state DOTs to ensure that smooth bridge decks are con- structed. The state DOTs that were selected for the interview were those in Florida, Mississippi, Nevada, New Jersey, Ohio, and Utah. Three of the selected state DOTs (Nevada DOT, Ohio DOT, and Utah DOT) use a smoothness specification that is based on the IRI, two of the selected state DOTs (Florida DOT and Mississippi DOT) use a smoothness specification that is based on profilograph measurements, and the other state DOT (New Jersey DOT) uses a specifica- tion that is based on a rolling straightedge simulation performed on the data collected with a walking profiler. The procedures to evaluate smoothness used by each state DOT are presented separately in this section. Case Example 1: Florida DOT Smoothness of concrete bridge decks that are less than 100 ft. long are evaluated using a straightedge 10 ft. long. The specified requirement is that when placed parallel to the travel direction, the distance between the bottom of the straightedge and the surface of the pavement should not exceed 3/16 in. The specification indicates the straightedge must be placed parallel to the centerline of the pavement, and in subsequent placements it must overlap 5 ft. of the previ- ous measurement. The approach slabs must also meet this specified criterion. Smoothness of bridge decks that are greater than 100 ft. long are evaluated using a computer- ized California-type profilograph, with the approach slabs also being tested. The contractor is required to perform this testing in the presence of a Florida DOT inspector. Measurement using an inertial profiler where a profilograph simulation can be performed on the collected data is not permitted. Measurements are performed along each wheelpath, and a PI for each wheelpath is computed using a blanking band 0.2 in. wide for each 300 ft. Thereafter, the PI for the left and the right wheelpaths are averaged to compute an average PI. The average PI must be less than 10 in./mi. to meet the specification. In addition, individual bumps or depressions exceeding a cutoff height of 0.3 in. based on a chord length of 25 ft. in each wheelpath must be corrected by grinding. The specification does not indicate a time period within which the smoothness testing must be performed after the concrete is poured. After the smoothness measurements are obtained, the bridge deck and the approach slabs are diamond ground longitudinally to a minimum depth of 0.25 in. The contractor is instructed to use the data obtained from the profilograph to select an optimum setting for the grinding machine. After diamond grinding has been performed, measurements are obtained again on the surface with a profilograph to ensure the specified overall PI criterion and the bump/depression C H A P T E R 4 Case Examples

40 Practices for Ensuring the Smoothness of Concrete Bridge Decks criterion have been met. The surface is also required to meet a transverse criterion if determined necessary by the engineer. The transverse criterion is that when a straightedge 10 ft. long is placed perpendicular to the travel direction on a lane, the distance from the bottom of the straightedge to the top of the pavement must be less than ¼ in. Thereafter, the bridge and the approach slabs are grooved in a direction perpendicular to the travel direction. Positive or negative pay adjust- ments for smoothness are not provided in the specification. AC overlay on a bridge is not common in Florida, but can happen from time to time. The Florida DOT construction specifications indicate that if an AC overlay is placed on a poured- in-place bridge deck, irregularities where the deviation from the bottom of the straightedge to the top of the pavement surface exceeds 0.25 in. when measured with a 10-ft. straightedge must be corrected. Case Example 2: Mississippi DOT Mississippi DOT uses a California profilograph to test the smoothness of concrete bridge decks. The smoothness testing is performed by a third party hired by the contractor in the pres- ence of a representative of the DOT. Computerized as well as non-computerized profilographs can be used for testing. However, inertial profilers are not allowed to collect data and perform a profilograph simulation on the collected data to obtain profilograph measurements. The bridge deck as well as the approach slabs are tested. Testing is performed on both wheel- paths of each lane. At the start of testing, the rearmost wheel of the profilograph is set as close as possible to the beginning of the entry approach slab, and testing is continued until the front wheel of the profilograph reaches the end of the exit approach slab of the bridge. Only the bridge deck is tested if the approach slabs are to be constructed under a future project. Profilograph testing is required on bridge decks and approach slabs on all state roads with four lanes or more and on state roads with three lanes or less where the current average daily traffic is 2000 vehicles or higher, or if designated on the plans. Bridge decks and approach slabs not requiring profilograph testing must meet a straightedge-based criterion based on a straightedge 10 ft. long. The criterion is that the deviation from the bottom of the straightedge to the top of the paved surface must be less than ⅛ in. in both the longitudinal and transverse directions. The PI is determined based on a zero-blanking band for each wheelpath of each lane, and then averaged to determine the average PI for the lane. The average PI for a lane cannot exceed 65 in./mi. In addition, in each wheelpath, individual bumps or depressions exceeding 0.3 in., based on a chord length of 25 ft., must be corrected. In addition to these requirements, the bridge deck and approach slabs must meet a straightedge criterion based on a 10-ft. straightedge. The straightedge criterion is that the deviation from the bottom of the straightedge to the top of the paved surface must be less than ⅛ in. in the longitudinal and traverse directions. Positive or negative pay adjustments for smoothness are not provided in the specification. Bridge decks and approach slabs not meeting the required criteria must be corrected by grind- ing according to the Mississippi DOT specifications. The contractor must submit a correction plan that describes areas to be ground to the DOT for approval before beginning work. After contractor has performed corrective work, the bridge deck and approach slabs must be tested again with the California profilograph to ensure that the specified criteria have been satisfied. If an AC overlay is placed on a bridge deck, there are no specifications to address the smooth- ness of the overlay. The current AC smoothness specification indicates smoothness measure- ments for construction acceptance should not be performed on approach slabs and bridge decks.

Case Examples 41   Mississippi DOT has been exploring introducing an IRI-based smoothness specification for bridge decks. They have been collecting data on new bridge decks after construction with an inertial profiler to compute the IRI levels that are currently being achieved on bridge decks. Case Example 3: Nevada DOT Nevada DOT uses an IRI-based smoothness specification for concrete bridge decks. This specification only has a localized roughness criterion and does not have an overall MIRI crite- rion. Nevada DOT adopted this IRI-based criterion in 2016. Before 2016, the Nevada DOT smoothness specification for bridge decks was based on a profilograph criterion. This criterion indicated that bumps/dips above 0.3 in. over a 25-ft. chord length should be corrected. This specification did not have an overall PI-based criterion. When the DOT adopted the IRI-based criterion, the profilograph bump criterion was replaced with a localized IRI criterion. The current smoothness specification for bridges requires that the pavement within 50 ft. of the leading edge of the bridge deck and within 50 ft. of the trailing edge of the bridge deck (including approach slabs) should be measured together with the bridge deck by an inertial pro- filer to determine IRI values. The contractor performs these measurements using contractor- owned equipment or hires a third party to perform these measurements. The contractor-owned or third-party equipment as well as the operator of the equipment must have been certified by the DOT in order to perform measurements. Two profiles are obtained on a traffic lane along the wheelpaths, while one profile is obtained on each shoulder. On the shoulder, profile measure- ments are performed approximately 3 ft. from the curb or rail face. When the combined width of the bridge deck and/or approach slab shoulder and adjacent traffic lane is 16 ft. or less, profile measurements are not needed for the shoulder. The maximum allowable IRI for localized rough- ness based on a 25-ft. moving average IRI is 175 in./mi. for each measured path. The smooth- ness specification also includes a straightedge criterion based on a straightedge 12 ft. long. The requirement is that when the straightedge is placed on the finished surface both perpendicular and parallel to the centerline of the bridge deck and approach slab, the distance between the bottom of the straightedge and the paved surface should not be more than 0.25 in. Quality assurance testing of the bridge deck is performed by the DOT at their discretion. Positive or negative pay adjustments for smoothness are not provided in the specification. The contractor is required to correct areas exceeding the specified localized roughness by grinding. The contractor must submit a corrective action plan to the DOT and have it approved before performing grinding. When the bridge deck and approach slabs are overlaid with AC, the smoothness specification specified for AC roads is applied to the overlaid bridge deck and approach slabs. AC surfaced pavements on Interstates in Nevada have an open-graded surface, and the smoothness specifi- cation for open-graded AC is applied to the bridge deck and approach slabs if the bridge is on an Interstate. Pay adjustments are provided for AC pavements on Interstates, and the contractor is required to achieve a MIRI between 45 and 55 in./mi. per 0.1-mi. section to receive full pay. Positive pay adjustments are provided if the MIRI is less than 45 in./mi. before correction, and negative pay adjustments are applied if the MIRI after corrections exceeds 55 in./mi. Any area of localized roughness exceeding 150 in./mi. or straightedge deviation exceeding 0.25 in. after correction is assessed liquidated damages of $2,500. This is in addition to the negative pay adjustments that are applied if the MIRI is over 55 in./mi.

42 Practices for Ensuring the Smoothness of Concrete Bridge Decks Pay adjustments are not provided for AC overlays on bridge decks located on non-Interstates. The DOT uses several different smoothness specifications for AC overlays placed on bridges that are on the non-Interstate system. The smoothness specification used depends on the existing MIRI of the road and speed limit. Case Example 4: New Jersey DOT New Jersey DOT started measuring the smoothness of newly placed concrete bridge decks using the SurPRO, which is a walking profiler, starting in about 2012. Before then, the smooth- ness was measured using a rolling straightedge. Materials Procedure MP Number 28-12, Bridge Deck Ride Quality Acceptance Testing Using Walking Profiler of the New Jersey Bureau of Materials, describes the procedures to be followed for data collection and analysis (New Jersey DOT 2012). The finished surface of the concrete bridge deck as well as approach slabs are mea- sured with the walking profiler, unless the approach slabs are excluded from the measurements based on the project documents. Measurements are performed on each wheelpath of each travel lane by DOT personnel. The measurements are typically performed after the concrete has been cured for 14 days after pouring. After the walking profiler data have been collected, a 10-ft. rolling straightedge simulation is performed on the collected data using the ProVAL software. The portion of the length mea- sured that exceeds a ⅛-in. tolerance based on the 10-ft. rolling straightedge simulation is then computed. Acceptance is based on the percentage of the total length of the lot having a surface variation exceeding ⅛ in. in 10 ft., which is defined as Lot Percent Defective Length. To compute the Lot Percent Defective Length, the lengths of individual surface defects exceeding the speci- fied tolerance are added for both wheelpaths and then divided by the sum of total length tested, and then multiplied by 100 to convert to a percentage. A lot is the cubic yard of deck concrete placed in the traffic lanes from joint assembly to joint assembly (typically the mechanical metal joints). The quantity of concrete in a lot is computed using the specified nominal deck thickness. The specified requirement is that less than 9% of the measured length of the lot should exceed ⅛-in. tolerance in 10 ft. If this value exceeds 9%, a reduction in payment per lot is applied. The reduction in payment per lot that is applied is shown in Table 20, and is based on the price of the concrete for the lot. If the Lot Percent Defective Length equals or exceeds 25% on any machine finished deck or 35% on a manually struck and finished deck, the engineer may order all the concrete in the lot to be removed, replaced, and retested for acceptance. If the engineer allows the concrete to remain in place, a 15% reduction to the payment for the lot is applied. A contractor can grind the surface to bring the surface to within specification and avoid the reduction in payment. For AC overlays that are placed on concrete bridge decks, an IRI-based smoothness specifica- tion is applied. The target IRI depends on the type of roadway (e.g., freeways or limited access roads, roads with a speed limit greater than 35 mph, or roads with a speed limit less than or equal to 35 mph) and the number of operations that are available to improve the smoothness (milling is considered to be one operation, and each lift of AC is another). Lot Percent Deflective Length (%) Price Reduction Per Lot (%) 0–8.9 None 9.0–13.9 1.0 14.0–24.9 7.0 25.0–34.9 (Manually finished deck) 12.0 Table 20. Price reduction per lot of deck slab concrete due to non-conformance with surface requirements.

Case Examples 43   Case Example 5: Ohio DOT Ohio DOT is the first DOT in the United States to implement a standard smoothness speci- fication on concrete bridge decks that was based on IRI. This specification was implemented in 2012. A study performed in 2001 by Ohio DOT found that bridges are 2.5 times rougher than pave- ments. At that time, Ohio DOT had a smoothness specification for concrete bridges that was based on a rolling straightedge 10-ft. long. The requirement in the smoothness specification was that there should be no deviations on the pavement surface exceeding ⅛ in. at the center of a 10-ft. rolling straightedge, based on the datum established by the wheels at the ends. In 2006, Ohio DOT introduced an experimental specification for bridges that was based on IRI. The main purpose of the experimental study was twofold, • To determine how smoothly bridges could be constructed prior to any correction, if the contractors were proactively trying to achieve smoothness based on IRI, and • To quantify the extent to which diamond grinding could improve smoothness. This specification defined a bridge encounter as 25 ft. of pavement before the entry approach slab, the entry approach slab, the bridge deck, the exit approach slab, and 25 ft. of pavement after that. The smoothness requirement in the specification was that the bridge encounter defined above for each lane must have a MIRI of less than 150 in./mi. This specification included a positive pay adjustment clause, which was paid if the contractor was able to achieve a MIRI of less than 150 in./mi. The positive pay adjustment varied, depending on the MIRI level that was achieved. The maximum positive pay adjustment was achieved when the MIRI was less than 80 in./mi., for which the positive pay adjustment was 20% of the price paid for the concrete in the deck. As this positive pay adjustment was applicable even after corrective action was per- formed on the bridge deck, a contractor could grind the bridge deck and approach slabs in the longitudinal direction after they were built to reduce the IRI and earn a positive pay adjustment. This specification did not include a clause related to localized roughness. Analysis of the results obtained after the experimental specification was implemented showed that grinding the entire bridge deck could reduce the MIRI by more than 50%. For example, in one project, grind- ing was able to reduce the MIRI to 77 in./mi. from 175 in./mi., while for another project, grind- ing reduced the MIRI to 82 in./mi. from 217 in./mi. Analysis of the results also showed that it was necessary to include a clause to address localized roughness in the smoothness specification. In 2012, Ohio DOT introduced a smoothness specification for bridge decks that was based on IRI, which was called Proposal Note 555. This specification could be used on all bridges irrespective of the type of bridge (e.g., integral, semi-integral, suspension, or cable stayed), the length of bridge, or the functional class of the highway on which the bridge was located. Similar to the experimental specification, a bridge encounter was defined as 25 ft. of pavement before the entry approach slab, the entry approach slab, the bridge deck, the exit approach slab, and 25 ft. of pavement after the exit approach slab. Positive or negative pay adjustments were not included in this specification. The specification required each lane of the bridge encounter to have a MIRI of 130 in./mi. or less. If this requirement was not met, the MIRI had to be corrected to a value of 100 in./mi. or less. This overall criterion was not applied if the length of the bridge encounter was less than 265 ft. A localized roughness criterion that was based on a 25-ft. moving average IRI was included in this specification. Each wheelpath in each lane was required to have a localized roughness IRI value that was less than 250 in./mi. However, this limit was increased to 350 in./mi. at any location where the 25-ft. base length included a steel armored joint. If the specified value was exceeded, such locations had to be corrected to have a value less than the specified value.

44 Practices for Ensuring the Smoothness of Concrete Bridge Decks Ohio DOT has 12 districts in Ohio, and bridge designs and specifications for bridges in each district are developed by the respective district offices. Each district had the option of using the smoothness specification for the bridge deck in a project. In 2021, Ohio DOT revised the smoothness specification. The main reason for revising the specification was twofold, • To encourage the contractor to achieve a higher smoothness level before any corrective action was performed and to reward the contractor for quality work, and • To have negative pay adjustments after corrective actions have taken place. The overall IRI criterion that was present in the previous specification was dropped in this specification. This specification provides for lump-sum pay adjustment based on a histogram analysis of localized roughness, which is performed using the ProVAL software. The ProVAL software can categorize the localized roughness within the measured length into predefined IRI bins based on length. Ohio DOT uses a value of 50 in./mi. for each bin; therefore, the bins are designated in ranges such as from 0 to less than 50 in./mi., from 50 to less than 100 in./mi., and from 100 to less than 150 in./mi. The collected profile data in each lane are analyzed using ProVAL, and a report that lists the length corresponding to each IRI bin of localized roughness is outputted by ProVAL for each wheelpath. Ohio DOT has separate tables that list the pay adjustments for localized roughness for loca- tions with and without steel armored expansion joints. For locations with and without steel armored expansion joints, positive pay adjustments are applied for locations that have a local- ized IRI value less than 200 in./mi. However, no positive pay adjustments will be made if any location has a localized roughness level of 250 in./mi. after correction, with this value being increased to 300 in./mi. for locations with armored joints. The positive pay adjustments vary depending on the IRI bin, with the pay adjustment increasing as the IRI value decreases. No pay adjustments are applied for the IRI bin between 200 and 250 in./mi. for locations without armored joints and 200 to 300 in./mi. for locations with armored joints. Negative pay adjust- ments are based on post-corrective data. Negative pay adjustments are applied for IRI bins that are between 250 and 600 in./mi. for locations without armored joints and for IRI between 300 and 600 in./mi. for locations with armored joints. The negative pay adjustment increases with the increasing value of the IRI bin. Corrective action is required for locations that are outside the limit of 600 in./mi. value for locations with and without armored joints. The smoothness specification indicates that the specification should be used on all projects with a new bridge deck and approach slabs, and at least 100 ft. of new pavement on either side of each approach slab. Each Ohio DOT district has the option of using this specification on projects with a lower length of approach pavement. The smoothness testing of the bridge is performed by the contractor using equipment certi- fied by Ohio DOT with the equipment operator also required to be certified by Ohio DOT. If the specified smoothness requirement could not be met, the contractor must submit a corrective action plan to Ohio DOT that describes how the required smoothness levels could be achieved. Once the corrective action plan is approved by Ohio DOT and implemented by the contractor, the contractor is required to collect profile data again on the bridge encounter to ensure that the smoothness requirements have been met. As described previously, the contractor can use a corrective action plan to reduce or eliminate the negative pay adjustment. Ohio DOT requires all bridges to be grooved longitudinally. Ohio DOT prefers the smooth- ness corrections to be performed before the bridge deck is grooved. However, in some projects where phased work is carried out by closing specific lanes, smoothness correction is not typi- cally performed before grooving. In such cases, the contractor will groove the bridge deck after performing work on that phase. Finally, after the entire project has been completed, the contractor

Case Examples 45   will collect the smoothness data on the bridge and perform any corrective action if required. Thereafter, the contractor is required to regroove areas that do not meet a specified criterion. Ohio DOT collects roughness data on its entire state network, which includes roads as well as bridges. Locations that have a localized MIRI of over 400 in./mi. (based on a 25-ft. moving average IRI) are shown on a web map. Ohio DOT districts can use these data to identify bridge approaches or bridges that have a high MIRI and take appropriate actions to reduce the roughness at such locations. At the request of Ohio DOT districts, the Ohio DOT office that oversees road profiling equipment can do project-level studies on bridge approach slabs and bridges to quantify the roughness level. They can also analyze the collected profile data to suggest corrective actions. Ohio DOT districts have the option of using the smoothness specification on concrete overlays. However, the decision of whether or not to use the specification on a concrete overlay will be based on the type of project. For example, if the project has a compressed time schedule, it is unlikely that the smoothness specification will be used. An AC overlay is rarely placed on bridge decks in Ohio. An AC overlay is only used if a con- crete overlay cannot be placed, or if it is known that the bridge deck will be replaced within 7 or 8 years. Ohio DOT districts have the option of using the smoothness specification that is used for asphalt roadways on the bridge in such a case. Case Example 6: Utah DOT Utah DOT uses an IRI-based specification for smoothness of concrete bridge decks. Utah DOT adopted this specification in 2018. Before that, Utah DOT had a specification for bridge decks that was based on the PI computed from profilograph data. The bridge deck, the approach slabs, and the pavement within 25 ft. of the entry approach slab and exit approach slab where the pavement is placed as part of the contract are included in the IRI-based specification. This specification is applied regardless of the length of the bridge deck. Profile data are collected along each wheelpath of a lane, and the IRI is computed for each wheelpath and then averaged to obtain the MIRI. The data are collected by the contractor using equipment that has been certified by the Utah DOT, and the equipment is operated by an opera- tor who is also certified by the Utah DOT. If the combined length of the approach slabs, the pavement 25 ft. on either side of the approach slab, and the bridge deck is less than 528 ft., the MIRI is based on the entire measured length. If the length of the approach slabs, the pavement 25 ft. on either side of the approach slab and the bridge deck is greater than 528 ft., the MIRI is based on intervals of 528 ft., with a partial seg- ment that is less than 528 ft. at the end. A MIRI of between 60 and 70 in./mi. must be achieved in order to receive full pay. Positive pay adjustments are applied if the MIRI is less than 60 in./mi., while negative pay adjustments are applied if the MIRI exceeds 70 in./mi. These pay adjustments for a section 528 ft. long are shown in Table 21. For segments shorter than 528 ft., incentives or disincentives are prorated based on the length of the segment from the values shown in Table 21. Corrective action is only required if the MIRI is over 90  in./mi. If the MIRI is over 90  in./mi., the surface must be corrected in order to reduce the MIRI to be less than 90 in./mi. The pay adjustments shown in Table 21 are the recommended values, and they can be changed for each project by the DOT. In addition to the MIRI requirement, localized roughness values based on a 25-ft. moving average IRI for each wheelpath that is over 15 ft. in length with an IRI of over 250 in./mi. must be corrected to a value that is 250 in./mi. or less. The contractor is required to collect preliminary data once the project is completed. There is no time limit after construction within which these measurements need to be obtained. Based on

46 Practices for Ensuring the Smoothness of Concrete Bridge Decks the collected data, the contractor must perform corrective action so that the specified MIRI cri- terion and the localized roughness threshold are met. Utah DOT encourages the contractors to provide the corrective action plan to the DOT for approval before performing corrective action. Acceptance testing of the bridge deck is performed by the contractor, after corrective action has been performed, in the presence of a Utah DOT engineer. Utah DOT may perform verifica- tion testing to check the data collected by the contractor. The contractor is not eligible to receive any incentive payments if any localized roughness remains in place after corrective action. The bridge deck also needs to meet a straightedge criterion in the transverse direction, where the distance from the bottom of a 10-ft. straightedge to the top of the pavement surface must be less than 3/16 in. Utah DOT has not performed many projects where AC overlays have been placed on concrete bridge decks. Typically, for AC overlay projects on bridge decks, smoothness specifications have not been applied. MIRI Range (in./mi.) Pay Adjustment ≤ 40.0 $1,000 40.1–50.0 $750 50.1–60.0 $500 60.1–70.0 $0 70.1–80.0 -$250 80.1–90.0 -$500 > 90 Corrective Action Table 21. Pay adjustments for bridge decks.