Gary Whited

Quantitative Methods for Design-Build Team Selection

Use of design-build (DB) contracting by transportation agencies has been steadily increasing as a project delivery system for large complex highway projects. However, moving to DB from traditional design-bid-build procurement can be a challenge. One significant barrier is gaining acceptance of a best value selection process in which technical aspects of a proposal are considered separately and then combined with price to determine the winning proposal. These technical aspects mostly consist of qualitative criteria, thus making room for human errors or biases. Any perceived presence of bias or influence in the selection process can lead to public mistrust and protests by bidders. It is important that a rigorous quantitative mathematical analysis of the evaluation process be conducted to determine whether bias exists and to eliminate it. The paper discusses two potential sources of bias – the evaluators and the weighting model – in the DB selection process and presents mathematical models to detect and remove biases should they exist. A score normalization model deals with biases from the evaluators; then a graphical weight space volume model and a Monte Carlo statistical sampling model are developed to remove biases from the weighting model. The models are then tested and demonstrated using results from the DB bridge replacement project for the collapsed Mississippi River bridge of Interstate 35W in Minneapolis, Minnesota.

Request for Information: Benchmarks and Metrics for Major Highway Projects

AbstractA request for information (RFI) is a formal written procedure initiated by the contractor seeking additional information or clarification for issues related to design, construction, and other contract documents. Large numbers of RFIs along with slow responses to RFIs are frequently cited as a metric for poor project performance. Implementation of an RFI process is an integral part of successful project management for construction projects that improves communication between the construction, design, and project management teams. The use of RFIs is common in vertical construction, but is just gaining use and acceptance in the delivery of transportation infrastructure projects. The purpose of this paper is to benchmark the RFI process and develop benchmarks and metrics to aid project teams in assessing the performance of a transportation infrastructure project and to provide best practices for improving the overall RFI process. Data on RFIs were collected from major highway construction projects in ...

Evaluation of Probing Versus Coring for Determination of Portland Cement Concrete Pavement Thickness

The Wisconsin Department of Transportation (DOT) has used contractor probing measurement of fresh portland cement concrete pavement to determine pavement thickness since 1998. Before that, the Wisconsin DOT used coring to measure thickness and determine payment for pavement. The probing method is nondestructive and has financial advantages for the Wisconsin DOT because it eliminates the costs of coring and reduces the expenses of contract administration. Probing also provides the contractor with immediate feedback on the depth of the pavement being constructed. A study was conducted to verify the reliability of probing measurement for determining pavement thickness and verifying contractors’ compliance with design requirements. To determine whether probing was still a viable method for use by the Wisconsin DOT in construction contract administration, core depths were compared with field-measured probe depths for 12 projects constructed between 2006 and 2008 across the state of Wisconsin. Sample means were compared, statistically calculated estimates of differences were examined, and a statistical analysis at the 95% confidence interval was carried out. According to these analyses, probing does provide an acceptable measure of pavement thickness. All contractor probe measurements and more than 80% of the Wisconsin DOT core samples showed that constructed pavement thickness exceeded the design thickness.

Planning the Implementation of Three-Dimensional Technologies for Design and Construction: Wisconsin Department of Transportation

The Wisconsin Department of Transportation (DOT) has developed a specification for highway subgrade construction by automated machine guidance (AMG). Wisconsin DOT is also deploying new design software, capable of providing three-dimensional (3-D) models required for AMG. During 2008, Wisconsin DOT, with assistance from the Construction and Materials Support Center at the University of Wisconsin–Madison, undertook a study of benefits and impediments to wider use of 3-D information in design and construction. The primary finding of a stakeholder workshop was that 3-D design and AMG are among a larger group of technologies and processes that have interrelated dependencies, synergistic benefits, and shared implementation issues. Thus, the studys objective was expanded to development of a high-level implementation plan for 3-D technologies and methods, in general, for highway design and construction in Wisconsin. The plan presents a vision, a management strategy, and six initiatives, including descriptions of backgrounds, issues, stakeholders, recommendations, goals, timelines, levels of effort, priorities, benefits, relationships with other initiatives, and responsible parties. The initiatives address an ongoing height modernization and continuously operating reference station program; standards, procedures, and training for 3-D data collection; 3-D model content and format standards; additional specifications for AMG; field technology and inspection; and infrastructure life-cycle uses of 3-D data. The plan differentiates between priorities (importance) and precedence (dependencies) among initiatives and goals within them. This information should be beneficial to other state highway agencies considering implementation of 3-D technologies.

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.

Probing Portland Cement Concrete Pavement for Thickness Determination in Wisconsin: Statistical Review

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.