Wisconsin Department Of Transportation Research Articles

Evaluating the Delivery and Oversight of State-Funded Local Bridge Projects

State-funded local bridge projects face several challenges including but not limited to constrained budgets, increasing burden from state departments of transportation (DOT) staff, and the lack of expertise of some local personnel. By streamlining the delivery and oversight of state-funded projects through delegation, a collaborative and proactive approach can be achieved, ensuring the successful maintenance and development of local low-risk bridges, which are not on the National Highway System and have minimal to no environmental, right of way, utility, or railroad impacts. This paper offers a practical approach to evaluating programs focused on progressing project delivery by delegating specific tasks and responsibilities to local governments. Taken as a study case, Wisconsin Department of Transportation’s low-risk bridge pilot program was evaluated using both a quantitative methodology: data analysis using a data-driven statistical approach involving analysis of pilot and control group data, and an evaluation of the performance metrics developed by the state DOT; and a qualitative approach: a survey of local sponsors and stakeholders about the pilot project. The survey corroborated the findings derived from the data analysis: improved performance in project cost and schedule for pilot projects, highlighting consistency and reliability in the evaluation process. The integration of both methodologies resulted in valuable insights and experiences, providing valuable guidance to other states conducting similar program evaluations.

Conceptual cost estimation of highway bid unit prices using ordinary kriging

State-of-the-art encompasses the application of deterministic and geostatistical algorithms to quantify the effect of spatial variation of unit prices across different locations. No studies have evaluated the efficacy of the different combinations of variogram and kriging models when used to characterize the spatial variability of major highway bid unit prices, as well as how well they predict future unit prices at unsampled locations. In this paper, ordinary kriging was combined with three commonly used semivariograms (spherical, exponential, Gaussian) models one at a time to predict six years of the top five common highway bid items obtained from the Wisconsin Department of Transportation (WisDOT) and evaluated the prediction uncertainty for each bid item. The results show that the best-performing combination of ordinary kriging and semivariogram varied depending on the type of bid unit-price data. This study advances the state of practice by comparing the efficacy of various combinations of the variogram and ordinary kriging models in predicting highway bid unit prices and provides insight into the models’ behavior in describing bid unit price spatial heterogeneity. Transportation agencies can employ this methodology to model other highway bid items and project types that have not been experimented in this study.

Long-Term Performance of Flexible Pavements Constructed on Recycled Base Layers

There has been an increased interest in using reclaimed asphalt pavement (RAP) aggregates as a base course in Wisconsin for the offered economic and environmental benefits. Laboratory studies showed that RAP can have resilient modulus values higher than typical natural aggregates, and can also have higher durability, especially in freeze–thaw cycles. However, it is also recognized that RAP exhibits temperature sensitivity and larger permanent deformations than natural aggregates. How these characteristics manifest themselves in the northern U.S. climates can only be assessed by long-term observation of field performance. Wisconsin Department of Transportation (WisDOT) has been using RAP as a base course for over 30 years. The qualitative assessment of WisDOT roads constructed with RAP showed they are performing adequately. However, this impression has not yet been verified quantitatively. This paper presents a quantitative assessment and comparisons for field performance of pavement test sections constructed with RAP and natural crushed aggregate (CA) base course layers in Wisconsin. The performance was evaluated using pavement distress surveys of roadways containing RAP and CA, falling weight deflectometer (FWD), dynamic cone penetrometer (DCP) tests, and analysis of WisDOT’s available data. Based on the field evaluation, the performance of the hot mix asphalt (HMA) pavements with RAP was found adequate and comparable to those with CA base course layers. A recommendation was given that WisDOT shall continue the practice of using RAP in base course layers of HMA pavements, given proper quality checks for materials, and proper quality control/quality assurance measures being applied during construction.

Critical Criteria for Aluminum Culvert Durability in Wisconsin

Current Wisconsin Department of Transportation (WisDOT) policy severely limits the use of aluminum drainage structures (pipe and box culverts) based on the observation of corrosion from deicing salts that led to the failure of an aluminum culvert in Wisconsin in 1993. The research goals were to establish best practices for aluminum culvert use and formulate recommendations for updated aluminum culvert policy in Wisconsin. The research included a literature review of aluminum culvert material specification and durability, of expected environmental conditions in Wisconsin, of policies and specifications from U.S. federal agencies, WisDOT, and five other state departments of transportation, published research, and manufacturer literature; development and administration of an aluminum culvert stakeholder survey; field inspection and site environmental characterization of three aluminum culverts in Wisconsin; a review of aluminum culvert inventory and inspection data from WisDOT and FHWA; and identification of best practices for aluminum culvert use in Wisconsin with recommended updates to WisDOT policy. Based on natural environmental conditions in Wisconsin, aluminum culverts should provide 50 to 75 years or more of service life if installed in sites that meet generally accepted abrasion, pH, and resistivity limits. Infiltration of chloride-based deicing chemicals through soil fill and contact with aluminum leads to pitting corrosion that may lead to premature culvert failure. Best practices to prevent this mechanism include installing an impermeable isolation membrane within the backfill, testing and limiting the chloride content of the embedment backfill, and using free-draining backfill below the membrane and as embedment around the buried structure.

State DOT Implementation of Statistical Analysis and Percent Within Limits

Verification testing, conducted by many state agencies, should serve an integral role in a quality assurance program. Many agencies seek a balance of physical and financial resources, as resources are routinely a limiting factor. For the Wisconsin Department of Transportation (WisDOT), it is datasets collected by both the contractor (quality control, QC) and department (quality verification, QV) at differing frequencies compared in a statistically valid method that provide balance. Statistical analyses, specifically F- and t-testing, have been chosen by WisDOT to accompany a Percent Within Limits (PWL) specification for hot mix asphalt (HMA). The analyses evaluate QC and QV data variances, means, standard deviations, and so forth, and determine whether it is reasonable to assume the test results of each dataset come from the same population, that is, are representative of the same material. If comparable, the more frequent QC data are considered verified and subsequently used in PWL calculations to approximate the percentage of material within specification limits. Anything less than comparable is subject to further investigation, for example, a dispute resolution process, to determine which test results most reliably represent the physical properties of the material, and are thus justifiably used in latter calculations. Such an approach has allowed WisDOT to adjust pay in accordance with material quality and consistency, ultimately connecting pay to anticipated long-term performance. This modified system of monitoring HMA materials has motivated multiple changes to industry processes and planning, and resulted in more consistent pavements, which should reduce the potential for isolated premature distresses.

Wisconsin Department of Transportation Hot-Mix Asphalt Round Robin Laboratory Qualification Testing Program

The Wisconsin Department of Transportation (DOT), Madison, uses a quality management program (QMP) specification for acceptance and payment of hot-mix asphalt (HMA) pavement. The QMP allows for product acceptance on the basis of contractor quality control (QC) testing when verified by the Wisconsin DOT quality verification (QV) tests. The contractor is required to do daily QC testing of mix properties in a department-certified, qualified laboratory located at the plant site. The Wisconsin DOT maintains a QV program (QVP) and conducts QV tests to determine the quality of the final product. QV and QC test results are compared, and a mix is considered acceptably verified if the two results are within specified limits. When test results do not meet these limits, the Wisconsin DOT performs referee tests to determine mixture conformance, acceptability, and payment. In 2011, the Wisconsin DOT began to see significant increases in the number of requests for referee testing as a result of wide disparities between QC and QV laboratory test results. To investigate this disparity, the department initiated a round robin laboratory test program. Results from the investigation proved to be insightful. The program was expanded and is now a key component of the Wisconsin DOT annual laboratory qualification certification program. This paper describes the program, how it is administered, how tests results are analyzed, and how nonconforming laboratories are identified. Test results obtained from the program are presented and recommendations developed for program improvements. The program details should be useful to other state highway agencies that use contractor QC tests for acceptance.

Use of performance-based testing for high RAP mix design and production monitoring

In 2014 the Wisconsin Department of Transportation and industry developed a pilot programme for hot mix asphalt with higher recycled asphalt content that required use of performance tests during mix design and production. Following the balanced mix design concept mixture tests were selected to address rutting resistance after short-term ageing and durability after long-term ageing. The tests selected were the Hamburg Wheel Tracking test, the Semi-Circular Bend (SCB) test at intermediate temperature, and the Disc-Shaped Compact Tension test at low pavement temperatures. Asphalt binder extraction and grading from aged mix was also required. The focus of this paper is to summarise the mixture performance test and recovered binder data gathered during the pilot project on State Highway 77 in Ashland County, WI, suggest modifications to the SCB test procedure, and to present accelerated ageing protocols for continued use of performance testing in practice. SCB test results collected during the project at 25°C did not relate well to values published in the literature or show adequate sensitivity to changes in mix properties. The effects of test temperature and an alternative analysis method are presented. Based on the results, recommendations include use of a climate-based approach for test temperature selection and inclusion of post-peak analysis to better discriminate between mix composition and ageing conditions. Accelerated long-term-ageing protocols involving loose mix ageing at 135°C for 12 and 24 h are compared to American Association of State Highway and Transportation Officials (AASHTO) R30 compacted mix ageing using recovered binder and mixture fracture properties. Results found that 12 h loose mix ageing produced similar recovered binder grading to AASHTO R30, whereas the effect of ageing on mixture fracture tests was inconclusive. The relationship between laboratory and field ageing is investigated through comparison of field cores to laboratory-aged plant-produced mix from a project constructed in SE Minnesota in 2006. Lastly, the laboratory performance of the high recycled and conventional mix designs are compared on the basis of mixture cracking resistance and recovered asphalt binder properties after extended ageing. The high recycle mix exhibited equal or better performance relative to the conventional mix across all selected performance tests. This comparative analysis also provides an example of how the inclusion of performance testing can influence the material selection process and produce test results indicative of improved overall performance of the mix.

Using vehicle simulations to understand strategies for accommodating oversize, overweight vehicles at roundabouts

There is considerable evidence that roundabouts are the safest and most efficient form of traffic control for most intersections. The potential use of roundabouts with all their inherent benefits may be greatly diminished if they are not able to accommodate oversize/overweight (OSOW) vehicles, sometimes called “Superloads.” The problem, therefore, is how to accommodate OSOW vehicles without sacrificing the integrity, safety and other benefits of roundabouts.This study uses TORUS software to design six standard roundabouts using guidance from the latest Federal Highway Administration (FHWA) roundabout guide. Six OSOW check vehicles from the Wisconsin Department of Transportation’s library were used to modify the designs to accommodate these selected check vehicles at the roundabouts. These six OSOW check vehicles were used to conduct swept path analysis using AutoTURN software at the selected six standard roundabouts for right turn, through, and left turn simulations. The space requirements for these maneuvers were analyzed in detail. Various strategies for better accommodating these OSOW check vehicles were suggested and experimented with in this study using AutoTURN software simulations. The effectiveness of using a straight passage through the center island for OSOW vehicles was also addressed in this study and was found to be effective. All the strategies investigated in this study proved to be effective in accommodating OSOW vehicles when compared to conventional ways of using a roundabout. The needed total truck apron was calculated and used as a reference to determine an effective strategy for accommodating OSOW vehicles. This research can be used as guidance for transportation engineers, planners and decision makers to determine possible ways of designing a roundabout at an intersection where certain OSOW vehicles are expected.

Developing a Chained Fisher Construction Cost Index for a State Highway Agency

Construction cost indexes (CCI) are important to state highway agencies (SHA) to provide an indicator of construction cost escalation over time and to update old bid cost information to current year pricing. The Federal Highway Administration publishes a National Highway Construction Cost Index (NHCCI) based upon cost data from several states for SHA to use. The Wisconsin Department of Transportation (DOT) uses a CCI to measure the changes in purchasing power of their construction dollar from one year to the next. Currently, the Wisconsin DOT uses a fixed-weight index to compute the CCI for a fixed basket of seven construction items. However, the current Wisconsin DOT CCI is subject to considerable short-term variation and does not accurately reflect the project bid costs that the department is experiencing. This paper presents results of a study requested by the Wisconsin DOT to develop an approach for calculating a more representative, reliable, and objective CCI. The paper presents various approaches to calculating a CCI, highlighting their properties and characteristics. The paper also outlines the process used to select a representative basket of items to calculate the index and outlines the data preparation steps needed to improve data quality. The recommended methodology uses a chained, two-stage aggregation computation process. This paper compares the newly constructed Wisconsin DOT CCI to the old CCI as well as to the NHCCI. The impact from selecting different size baskets of items is also investigated; it is concluded that a basket containing a representative number of items is sufficient to calculate a reliable CCI.

Extreme Vehicle Loads on Bridges: Evaluating and Regulating Farm Equipment in Wisconsin

In May 2014, the Wisconsin legislature passed Act 377. Among other things, the act creates an increased weight allowance for vehicles classified as implements of husbandry (IoH), known to most simply as farm vehicles. These vehicles, which are both large and heavy, were designed for use in the field, but in today’s modern infrastructure, they must sometimes navigate roads and bridges as well. The increased weight allowance is a modification of the federal bridge formula (FBF). It allows IoH to operate at 15% above FBF limitations for both axle and gross weights. The act includes partial exemptions for certain implements and creates a permitting structure for implements that exceed the stated limits. The act attempts to strike a balance between the needs of the farming community in Wisconsin and the effects of heavy vehicles on the inventory bridges in the state. In this paper, the work done by the Wisconsin Department of Transportation’s Bureau of Structures to render a structural recommendation concerning operation of IoH on the Wisconsin bridge inventory is documented. Both analysis work to assess risk to the inventory as a whole and permitting processes and procedures to address IoH on a more local level are included. The intent is that other state departments of transportation and infrastructure owners benefit from Wisconsin’s experiences.

Field Validation of a Thermal Cracking Resistance Specification Framework for Modified Asphalt

Current Superpave® performance grade (PG) binder specifications, such as those used in Wisconsin and many other states, were developed primarily for unmodified binders and are valid only within the linear viscoelastic range of properties. Further, performance benefits from modification are not limited to continuum rheological properties because modified binders often demonstrate superior damage resistance not captured in the current PG system. This paper discusses the results of a recently completed research project sponsored by the Wisconsin Department of Transportation in Madison; the objective was to identify promising procedures through a comparison of test results with field performance and the development of appropriate modified binder specification criteria for thermal cracking resistance. A number of procedures have been introduced in recent years to address the need for damage characterization test procedures for proper assessment and selection of modified binders. In this study, the single-edge notched bending (SENB) procedure was found to correlate well with the observed field thermal cracking when tests were conducted at the project location low-temperature PG specification temperature. The device used was a modified bending beam rheometer (BBR), which could perform displacement-controlled loading with higher load cell capacity, and accommodated notched BBR beams. On the basis of the results of this study, a procedure was introduced for thermal cracking resistance potential of modified binders with the BBR-SENB test at an average annual minimum pavement temperature of +10°C. A preliminary failure limit and acceptance criterion were defined to qualify binder results in terms of the failure properties measured.

Probing Portland Cement Concrete Pavement for Thickness Determination in Wisconsin

The Wisconsin Department of Transportation (DOT) has used probing of fresh concrete to determine the thickness of portland cement concrete pavements since 1998. Two earlier studies that compared the results from probing and coring in Wisconsin DOT projects concluded that probing did provide an acceptable measure of pavement thickness, but it was recommended that an annual coring program be instituted to verify the probing results. This paper compares core depths with probe measurements for all the projects conducted by the Wisconsin DOT from 2006 to 2011 where both core and probe data were available. A total of 32 projects were analyzed, representing more than 6,600 probes and 1,200 cores. A statistical analysis was done to determine if the core and probe measurements gave the same results. A simulation model was developed to analyze the power of the t-test to predict whether the two measurements are the same and to develop sample sizes needed to ensure that the two measurements differ only by a preselected amount. Results indicate that there are small, yet somewhat negligible in practice, differences between the core and probe methods of measurement. Recommendations are given for sample sizes needed on the basis of the size of the acceptable difference between the two methods.

Data Density Requirements as Functions of Design Speed

When designed, horizontal and vertical highway alignment components are parametrically described geometric objects (e.g., smooth curves and straight lines). However, surface models resulting from highway design and for use in construction by automated machine guidance (AMG) are not geometrically smooth. Rather, they are triangulated irregular networks containing straight line segments that serve as edges of contiguous triangular facets. Designers and construction contractors must decide how frequently to discretize parametric design objects for adequate representation by such line segments in surface models. Higher data frequencies, or densities, result in more accurate representations of design. However, high data densities lead to large file sizes, greater storage and data management requirements, and greater data transfer times. This paper presents mathematical derivations that relate minimum required data densities to error tolerances for horizontal and vertical curves. Geometry, physics, and quantifiable human factors are used to couple expressions of tolerable error with parameters of curves and, more fundamentally, with design speeds. An example is provided in which the method was used to produce interim standards for electronic design–AMG for data-sharing pilot projects with the Wisconsin Department of Transportation. The mathematics should be straightforward for incorporation in design software to ensure that individual design objects, groups of objects, or entire corridors are represented to acceptable levels of accuracy, with minimum data requirements, in surface models used for construction by AMG. The scope of this research is limited to control of discrete errors in representations of smooth curves by straight line segments. Uncertainties resulting from measurements are not addressed.

Translating Transportation Data between Linear Referencing Systems of Dissimilar Resolution

The Wisconsin Department of Transportation uses two linear referencing systems (LRSs) for complete mapping of crashes statewide: the State Trunk Network (STN), which represents only state routes, and the Wisconsin Information System for Local Roads (WISLR), which includes all roads but gives specific detail for local routes. A functional link between the two systems was developed; this link allows data to be translated from the STN, a higher-resolution representation, to the WISLR, a lower-resolution representation. Although data are easily translated from high to low resolution, ambiguities arise when data are moved from low resolution to high resolution. The research presented in this paper identifies common problems associated with translation of data from low to high resolution and provides some rules and guidelines to accommodate these issues.

Using Propensity Scores to Reduce Case-control Selection Bias

To the Editor: When sampling frames differ for cases and controls in a population based study, there are several analytical options to increase study validity. One is to exclude cases not found in the sampling frame for controls. Another, when the case sampling frame is nearly complete, is to link cases to the sampling frame for controls in order to obtain the information needed to model coverage propensity scores.1 Propensity scores have been used to address selection bias due to non-response and treatment-selection,2, 3 but we have found no studies that used propensity scores to address selection bias due to inadequate sampling frame coverage. We describe such an application here. Our analyses use data from the Wisconsin Women’s Health Study. Cases were women with incident invasive breast cancer reported to Wisconsin’s mandatory cancer registry. Controls were identified using a master file of licensed drivers who consented to have their private information released by the Wisconsin Department of Transportation. An estimated 68% of Wisconsin women with valid driver’s licenses provided this consent in 2008.4 Case eligibility was limited to women with a Wisconsin driver’s license (verified by self-report). We calculated odds ratio (OR) estimates of breast cancer risk using 3 established methods to correct selection bias, and compared these with published estimates.5, 6 The 3 methods were (1) excluding cases not in the control sampling frame, (2) applying propensity scores as weights, and (3) using quintiles of propensity scores to stratify analyses. We calculated standard errors of OR estimates to compare their precision. Additional details, including study inclusion criteria, are described elsewhere.4 The 2,988 breast cancer cases were linked to the driver’s license file to determine whether cases matched a record from the master-file of drivers (sampling frame for controls).4, 7 Propensity scores for inclusion in the sampling frame were calculated using logistic regression of 24 potential confounding factors ascertained through interviews with participants. The Table shows results of applying the 3 correction methods to a re-analysis of antidepressant medications and breast cancer risk.6 Of the 3 methods, stratifying by quintile of propensity score produced odds ratio3 with the best precision. Weighting, stratification and exclusion produced odds ratio3 with a similar degree of bias correction. However, the odds ratio3 changed only slightly after applying any of the correction methods. Similar results were found in another re-analysis of breast cancer risk, that one in relation to reproductive factors.4 Historically, the standard procedure in epidemiologic case-control studies has been to exclude cases that could not have been approached to serve as controls.8 This procedure assumes that factors that predict inclusion in the control sampling frame are similar for cases and potential controls. The two propensity-score-based methods implemented here also require this assumption and in addition, require correct model specification for propensity score estimation. The advantage of the propensity score methods is that they preserve the study base by allowing all cases to be used. Selection bias caused by incomplete sampling-frame coverage is frequently overlooked. In this study we linked the case and control sampling frames to demonstrate the use of propensity scores to adjust for selection bias due to incomplete study-base coverage of the sampling frames.

Selection Bias in Population-Based Cancer Case–Control Studies Due to Incomplete Sampling Frame Coverage

Increasing numbers of individuals are choosing to opt out of population-based sampling frames due to privacy concerns. This is especially a problem in the selection of controls for case-control studies, as the cases often arise from relatively complete population-based registries, whereas control selection requires a sampling frame. If opt out is also related to risk factors, bias can arise. We linked breast cancer cases who reported having a valid driver's license from the 2004-2008 Wisconsin women's health study (N = 2,988) with a master list of licensed drivers from the Wisconsin Department of Transportation (WDOT). This master list excludes Wisconsin drivers that requested their information not be sold by the state. Multivariate-adjusted selection probability ratios (SPR) were calculated to estimate potential bias when using this driver's license sampling frame to select controls. A total of 962 cases (32%) had opted out of the WDOT sampling frame. Cases age <40 (SPR = 0.90), income either unreported (SPR = 0.89) or greater than $50,000 (SPR = 0.94), lower parity (SPR = 0.96 per one-child decrease), and hormone use (SPR = 0.93) were significantly less likely to be covered by the WDOT sampling frame (α = 0.05 level). Our results indicate the potential for selection bias due to differential opt out between various demographic and behavioral subgroups of controls. As selection bias may differ by exposure and study base, the assessment of potential bias needs to be ongoing. SPRs can be used to predict the direction of bias when cases and controls stem from different sampling frames in population-based case-control studies.

Evaluation of Performance of Automatic Vehicle Location and TowPlow for Winter Maintenance Operations in Wisconsin

Winter maintenance operations are a major expense for state departments of transportation located within the Snow Belt of North America. Winter maintenance-related expenses for 2005 through 2010 ranged from $46 million to $87 million per year for state highways in Wisconsin. During the past two winters, the Wisconsin Department of Transportation implemented TowPlow and automatic vehicle location (AVL) technologies to optimize winter maintenance operations. A TowPlow is a plow that is attached to a regular plow truck to increase the snow removal capacity. AVL is a combination of systems capable of monitoring the location of a vehicle, material application rates, and road conditions from a central location. In this paper, qualitative and quantitative evaluations are presented for these two technologies. Findings from both evaluations showed that the implementation of these technologies would result in potential cost savings resulting from lower salt usage (AVL) and more efficient operations (TowPlow). The use of a TowPlow to perform the same task as a regular plow truck resulted in 32% to 43% operational cost savings. Implementation challenges, maintenance issues, and reduction in salt usage by counties that implemented AVL were evaluated. Implementation of AVL resulted in about 6% savings in salt usage from increased plow operator compliance with guidelines. When only the savings in salt usage and none of the intangible benefits were considered, the benefit–cost ratio values ranged from 1.05 to 1.89 depending on the cost of salt and percentage of reduction in salt usage.

DRB Enhanced Partnering on the Marquette Interchange: Case Study

Completion of the Marquette Interchange Reconstruction project by the Wisconsin Department of Transportation (WisDOT) under budget, ahead of schedule, and with no construction claims at the end of construction was a significant achievement and details of how it was accomplished provide valuable lessons for other public works projects. A standing Dispute Review Board (DRB) ensured that disputes did not linger and affect working relationships, use of partnering ensured effective communication between WisDOT and the contractor, and combining the two by having the DRB chair as an active participant in the partnering effort were identified as being vital to the success of the Core project. This paper describes the contractual establishment of the DRB, the formation and operation of the panel throughout the duration of the project, details of partnering participation requirements and utilization, and then identifies how the two programs were linked by mutual agreement between WisDOT and the prime contractor and...

Wisconsin Method for Probing Portland Cement Concrete Pavement for Thickness

Since 1998 the Wisconsin Department of Transportation (DOT) has used contractors' probing measurements instead of coring to determine aportland cement concrete (PCC) pavement thickness. This study compares core depths with probe depths for 13 projects constructed in 2008 and 2009 across the state of Wisconsin. A statistical comparison of sample means, estimates of differences, and an analysis at 95% confidence interval were completed. The results of this study were compared with results of a 1998 study by Wisconsin DOT and a 2008 follow-up study by the Construction and Materials Support Center (CMSC) at the University of Wisconsin–Madison. Approximately 69% of the projects studied met the criterion of equal means. In comparison, 25% met the criterion in the 1998 Wisconsin DOT study and 50% in the 2008 CMSC follow-up study. In addition, this study determined the preferred number of cores needed to perform a t-test for future quality verification studies by Wisconsin DOT. The study showed that five to 10 cores are required, depending on the pavement area. When the t-test was done with the ideal number of cores, 100% of the projects studied met the criterion of equal means. The study also compared probing for projects built on granular base versus those on hot-mix asphalt (HMA) base. The results showed that projects built on HMA base had a higher degree of comparison. This study also compared productivity and accuracy of probing with coring and other nondestructive measurement techniques. The study demonstrates that probing is an accurate and efficient method of determining depths of PCC pavement and can replace coring.

Developing an Asset Management Tool to Collect and Track Commitments on Environmental Mitigation Features

Wisconsin has constructed many environmental mitigation projects in conjunction with transportation projects under the National Environmental Policy Act. These projects offset or replace certain environmental function(s) lost as a result of a transportation project. Examples include storm water management facilities, wetland replacements, stream restorations, reforestation, construction of sound walls, replacement of parklands, and wildlife crossing structures. For environmental mitigation projects to provide the long-term functionality intended when they were first constructed, they must be properly maintained and, when necessary, rehabilitated or reconstructed. These environmental mitigation features should be considered as assets, similar to other transportation facilities. The Wisconsin Department of Transportation (WisDOT) identified the need to track these selected features in the overall scheme of project development and ongoing maintenance. This paper explores the current state of environmental mitigation project activities, discusses the literature on existing environmental inventory and asset management programs, presents an inventory of selected environmental mitigation features for Wisconsin, and develops a tool to track commitments. The tool was designed to assist WisDOT in monitoring the long-term performance of mitigation features. The research approaches used to develop the tracking tool, the list of priority features, and the inventory included interviews with WisDOT and Wisconsin Department of Natural Resources staff, a review of WisDOT's environmental records—such as environmental impact studies and environmental assessment documents—and a literature survey covering best practices for environmental tracking and asset management systems being used by other state agencies.