Maryland State Highway Administration Research Articles

A Conflation Methodology for Two GIS Roadway Networks and Its Application in Performance Measurements

In the current environment, in which private sector organizations play an ever increasing role in providing traffic data and tend to report data based on proprietary maps, it is inevitable that public sector agencies will want to adapt the spatial data and to use it in their legacy systems. Thus, for the same transportation infrastructures, a variety of GIS roadway datasets based on different highway reference location systems and segmentations are developed. This paper presents a method and a workflow to conflate such networks. The matching process usually involves projecting one network onto another. The first step in this process is to match the typically proprietary private sector network with the public sector legacy network. Different public and private entities may use different location referencing systems for analysis and reporting of data. So, in most cases, it is necessary to transform the spatial data from one location referencing system to another. Geographic information systems (GIS) offer a powerful tool for this purpose. GIS uses standard referencing systems to locate the features in a transportation network. This study proposes a methodology that takes advantage of GIS capabilities in the projection of transportation networks. A workflow is introduced based on the proposed methodology. A tool is created to perform the projection in the ESRI ArcGIS environment. Sanity checks and some reporting options are presented. Results are reported on projecting a subset of the Highway Performance Measurement System (HPMS) used by Maryland State Highway Administration onto the Traffic Message Channel (TMC) network in Maryland.

Monitoring study of the near-road PM2.5 concentrations in Maryland

The Maryland State Highway Administration (SHA) monitoring program monitored the impact of vehicular emissions on the concentrations of the fine particles smaller than 2.5 microns (PM2.5). PM2.5 concentrations were monitored in close proximity to a highway in order to determine whether traffic conditions on the roadway impact concentrations at this location. The monitoring program attempted to connect monitored concentrations with the roadway traffic exhaust or with the other sources of PM2.5. PM2.5 concentrations were collected near the Capital Beltway (I-495/I-95) in Largo, Maryland. The monitoring program was launched on May 13, 2009 and continued through the end of 2012. Two co-located monitors, one for continuous PM2.5 measurements and the other for speciation measurements, were used in this program. Meteorological and traffic information was also continuously collected at or near the monitoring site. Additionally, data from the two other monitoring locations, one at the Howard University-Beltsville, MD and one at McMillan Reservoir, DC, was used for comparison with the data collected at the SHA monitoring location. The samples collected by the speciation monitor were analyzed at the RTI and DRI Laboratories to determine the composition and the sources of the collected PM2.5 samples. Based on the apportionment analysis, the contribution of roadway sources is about 12 to 17 percent of PM2.5 at the near-road site.Implications: PM2.5 monitoring at 150 m (approximately 500 feet) from a major highway in Maryland near Washington, DC, demonstrated that roadway traffic contributes to the total PM2.5 concentration near the roadway, but the contribution at such distance is small, in the order of 12–17% of the total.

Innovations in Utility Conflict Management

Utility issues remain one of the top reasons for delays in development and delivery of transportation projects. Delays in utility relocations and varying site conditions (utility conflicts) are consistently ranked among the most frequent causes for delays in highway construction. This paper described the results of a pilot implementation of the utility conflict matrix (UCM) tools that were developed as part of SHRP 2 Project R15B in 2012. The implementation project was SHRP 2 R15C, Pilot Application of Products for the Identification of Utility Conflicts and Solutions, which took place from September 2012 to March 2014. The objective was to work with a state department of transportation on the implementation of the stand-alone UCM and the 1-day UCM training course, as well as an introduction to the utility conflict data model and database. The pilot implementation took place at the Maryland State Highway Administration. This paper describes the UCM tools, details of the pilot implementation, feedback received from stakeholders involved in the project, and lessons learned from the experience of project participants. The paper also provides examples of cost and time savings that resulted from the use of the UCM approach.

Data- and Performance-Based Congestion Management Approach for Maryland Highways

Across the country, state departments of transportation face challenges because of limited budgets and increased infrastructure needs. These agencies often are required to make and defend difficult decisions on project prioritization. With the increased availability of data, more quantitative measures can be used to assist in defining the most pressing project needs to improve mobility. This paper summarizes the findings of the 2012 Maryland State Highway Mobility Report, which evaluates the roadway transportation system operations and is a tool for assessing the annual progress of the state's roadway network. With a focus on policies, programs, and projects that systematically address both the recurring and nonrecurring nature of congestion, the Maryland State Highway Administration (SHA) has adopted a performance-based approach to provide users with a high-quality, reliable highway system. Four key focus areas were identified: mobility and reliability, incident management and traveler information systems, multimodalism and smart growth, and freight. Performance measures included input measures, such as vehicle miles traveled, travel time index, and planning time index; output measures, such as number of incidents cleared; and various analyses, such as the annual user cost savings attributable to congestion management. In addition, major controlled access corridors were evaluated from the standpoints of congestion, reliability, and bottlenecks with a combination of vehicle probe speed data and traffic volume data. Consistent performance monitoring allowed SHA to compare and prioritize projects much more effectively.

Development of Planning-Stage Models for Analyzing Continuous Flow Intersections

Despite the increasing use of continuous-flow intersections (CFIs) to contend with the congestion caused by heavy through and left-turn traffic flows, a reliable and convenient tool for the traffic community to identify potential deficiencies of a CFI’s design is not yet available. This is due to the unique geometric feature of CFI, which comprises one primary intersection and several crossover intersections. The interdependent relationship between traffic delays and queues at a CFI with five closely spaced intersections cannot be fully captured with the existing analysis models, which were developed primarily for conventional intersections. In response to such a need, this study presents a comprehensive analysis for the overall CFI delay, identifies the potential queue spillback locations, and develops a set of planning-stage models for the CFI design geometry. To facilitate the application of these proposed models, this paper also includes a case study of a CFI at the intersection of MD 4 and MD 235 constructed by the Maryland State Highway Administration.

Evaluation of Superpave HMA Mixture Properties at the Plant versus behind the Paver: Statistical Comparison of QC and QA Data

State highway agencies concerned with lower asphalt levels and potential durability problems in hot-mix asphalt (HMA) mixtures designed with superior performing asphalt pavements (Superpave) have lead efforts to explore strategies for improving Superpave mix design. This study addressed the differences in HMA properties that have been observed over the years between samples taken at the plant versus behind the paver for Superpave designed mixtures in Maryland. A large set of Maryland State Highway Administration (MSHA) quality assurance (QA) and quality control (QC) data were analyzed statistically in the context of current specifications. Statistical analysis found that the means and standard deviations of the QC and QA data represent different populations. Because the material leaving the asphalt plant is the same material that is compacted behind the paver, some relationship between the plant and field properties is expected. However, attempts to define transfer functions between QA and QC measurements to use both data sets in HMA acceptance testing encountered low levels of statistical significance.

Robust Plans and Contingent Plans

Problem: The practice of scenario planning is often too focused on developing a single preferred scenario and fails to adequately consider multiple uncertain futures. The U.S. Department of Housing and Urban Development recently awarded grants for scenario planning at regional and metropolitan scales that further promote this practice. However, a lack of systematic analysis of uncertainty limits the role of scenario planning. Purpose: The purpose of this article is to demonstrate how to incorporate uncertainty into large-scale scenario analysis and then use that framework to identify contingent and robust plans. Methods: We adapt the concepts of controllable internal options and uncontrollable external forces and consider their interactions in order to develop future scenarios and identify contingent and robust decisions. We then apply this technique using advanced econometric, land use, and transportation models developed for the Baltimore–Washington metropolitan region and its vicinity. Finally, based on the results of a hypothetical, yet plausible, exercise, we show how contingent and robust decisions can help local and regional governments develop contingent and robust plans. Results and conclusions: Scenarios developed as a combination of internal options and external forces allow us to identify a wider range of future impacts than in traditional metropolitan scenario planning. Robust plans support choices that offer benefits across scenarios. Contingent plans can be tailored to specific futures. Takeaway for practice: By providing a way to think systematically about uncertainty, scenario analysis promises to improve the efficacy of large-scale planning. Research support: This article was not directly supported by any outside agency, but support for the modeling system was provided by the following organizations: Maryland State Highway Administration, Maryland Department of Transportation, Maryland Department of Planning, U.S. Environmental Protection Agency, and Lincoln Institute of Land Policy.

Development and Validation of Pavement Performance Models for the State of Maryland

The Maryland State Highway Administration (SHA) is in the process of restructuring and improving its existing program for pavement system preservation. As part of this effort, SHA revised the process for its pavement management system (PMS) and developed a new software tool to handle the data analysis requirements. The authors present the analysis that led to the development of the pavement performance models of the PMS simulation that forecast pavement condition and prescribe maintenance and rehabilitation treatments. SHA had used hundreds of performance models to accommodate every state region, traffic level, and pavement type, treatment, and condition. To reduce the number of existing performance models, a statistical analysis was performed with the international roughness index (IRI) to identify groups with similar characteristics by pavement and treatment type. Once distinct groups were defined, the authors used a novel histogram-based analysis method to develop performance models based on IRI. This type of analysis was necessary to estimate realistic pavement deterioration rates without regard to pavement age. Independent pavement sections with good correlation were used to validate the performance models developed with the histogram-based analysis. In addition, the network-level prediction of pavement performance yielded satisfactory results with the developed performance models.

Beyond on-site mitigation: An integrated, multi-scale approach to environmental mitigation and stewardship for transportation projects

Federal, state, and local governments construct thousands of kilometers of roads each year in the U.S.A., as well as undertaking widening, rerouting or repair projects. Under the National Environmental Policy Act (NEPA), environmental impacts from such construction must be offset by mitigation measures (e.g., stream or wetland restoration). Unfortunately, restoration projects often are opportunistic, do not consider a broad landscape context, and have a low benefit–cost ratio. In 2007, the Maryland State Highway Administration asked The Conservation Fund, the Maryland Department of Natural Resources, and the U.S. Fish and Wildlife Service to help identify and evaluate natural resource stewardship opportunities in four Maryland watersheds that could potentially be affected by construction of a highway bypass. Stewardship activities, including conservation, restoration, or management of natural resources, would go above and beyond required mitigation. After soliciting feedback from stakeholders and reviewing pertinent literature, we modeled and validated a conservation network of high-quality wildlife and plant habitat (core areas), large contiguous natural areas (hubs), and linkages to facilitate wildlife movement and gene flow (corridors). We then ranked elements of this network at multiple scales, and identified high priority areas for conservation and restoration. Finally, we developed and tested protocols for field assessment and benefit–cost optimization. We hope that this approach can be adapted and improved by highway agencies and other entities for environmental planning and protection, and have a report available upon request with full details.

Confidence Level and Efficient Sampling Size of Roughness Measurements for Pavement Management in Maryland

The international roughness index (IRI) is the primary index of the Maryland pavement management system and is the data source for performance trend analysis, budget allocation, and project selection. The Maryland State Highway Administration (MDSHA) makes a significant investment to collect, process, analyze, and store IRI data every year over the entire network of the roads. Such reliance on IRI data and investment instigated the investigation of the confidence level embedded in the data and of devising possible sampling scenarios. To evaluate the confidence level, repeatability errors of the measurements were assessed. IRI data were repeatedly collected over a designated test loop under normal operating conditions to mimic network-level data collection. Sampling scenarios were devised using the Monte Carlo method for network IRI data collected in 2008. The network was stratified on the basis of functional classifications. Sampling errors in estimating the percentage of the roads in each of five IRI categories established by MDSHA were evaluated. The results indicated that the repeatability error of the measurements was less than 7%. The sampling results indicated that the state may survey a third of the network each year and expect estimation errors of less than 0.5% for all IRI categories. As such, MDSHA would not incur a considerable sacrifice in the confidence of network condition evaluation.

Evaluation of Maryland Abutment Scour Equation through Selected Threshold Velocity Methods

The U.S. Geological Survey, in cooperation with the Maryland State Highway Administration, used field measurements of scour to evaluate the sensitivity of the Maryland abutment scour equation to the critical (or threshold) velocity variable. Four selected methods for estimating threshold velocity were applied to the Maryland abutment scour equation, and the predicted scour to the field measurements were compared. Results indicated that performance of the Maryland abutment scour equation was sensitive to the threshold velocity with some threshold velocity methods producing better estimates of predicted scour than did others. In addition, results indicated that regional stream characteristics can affect the performance of the Maryland abutment scour equation with moderategradient streams performing differently from low-gradient streams. On the basis of the findings of the investigation, guidance for selecting threshold velocity methods for application to the Maryland abutment scour equation are provided, and limitations are noted.

Application of Advanced Traffic Information Systems

With increased congestion in most urban networks, providing reliable trip times to commuters has emerged as a critical challenge for all existing advanced traffic information systems. This paper presents the development and evaluation of a hybrid travel-time prediction model in a demonstration system sponsored by the Maryland State Highway Administration. The automated real-time travel-time prediction system is located on a 25-mi stretch of I-70 eastbound from MD-27 to I-695, which includes seven interchanges and 10 traffic detectors. To contend with the resource constraints of more than 1 mi in detector spacing, the proposed prediction model consists of two components: a multitopology neural network model with a clustering function as the main model and an enhanced k nearest neighbor model as the supplemental model. The evaluation results based on estimated travel times and field data collected by a third party indicate that the proposed hybrid model can provide reliable predictions of travel times in real-time operations in uncongested, congested, and transition traffic conditions.

Visual Analytics for Transportation Incident Data Sets

Transportation systems are being monitored at an unprecedented scope, which is resulting in tremendously detailed traffic and incident databases. Although the transportation community emphasizes developing standards for storing these incident data, little effort has been made to design appropriate visual analytics tools to explore the data, extract meaningful knowledge, and represent results. Analyzing these large multivariate geospatial data sets is a nontrivial task. A novel, web-based, visual analytics tool called Fervor is proposed as an application that affords sophisticated, yet user-friendly, analysis of transportation incident data sets. Interactive maps, histograms, two-dimensional plots, and parallel coordinates plots are four featured visualizations that are integrated to allow users to interact simultaneously with and see relationships among multiple visualizations. Using a rich set of filters, users can create custom conditions to filter data and focus on a smaller data set. However, because of the multivariate nature of the data, finding interesting relationships can be a time-consuming task. Therefore, a rank-by-feature framework has been adopted and further expanded to quantify the strength of relationships among the different fields describing the data. In this paper, transportation incident data collected by the Maryland State Highway Administration's CHART program are used; however, the tool can be easily modified to accept other transportation data sets.

Field Performance of the Fiber-Reinforced Polymer Deck of a Truss Bridge

The MD 24 Bridge over Deer Creek in Harford County, Md., was one of the projects chosen by the Federal Highway Administration’s Innovative Bridge Research and Construction Program for bridge deck replacement by fiber-reinforced polymer (FRP) composites. A thorough discussion is presented on Maryland State Highway Administration’s first bridge rehabilitation project utilizing a FRP deck. The discussion includes design details, installation procedure, construction methods and in situ load testing with a wireless monitoring system. The research team installed a monitoring system to record the effects of live loads on the bridge system, including truss members, steel stringers, and plate action of the FRP deck. Finite-element models were also used in this phase. Dynamic effects of the FRP system, composite action between steel stringers and the FRP deck as well as the effective width and distribution factors of stringers were obtained and compared with the AASHTO specifications. Recommendations are also offer...

Dynamic Late Merge Control at Highway Work Zones

The purpose of this study is to present the evaluation result of a dynamic late merge (DLM) system for highway work zone operations, experimented by the Maryland State Highway Administration and International Road Dynamics Inc. The evaluation focuses mainly on the operational efficiency such as the input–output analysis, work zone throughput, volume distribution, and resulting queue length. Evaluation results reveal that a properly deployed DLM system can indeed outperform the conventional merge control with respect to the total work zone throughputs. Such a system, however, may result in excessive traffic conflicts if not properly integrated with existing static warning signs for work zone operations. Some suggestions and guidelines developed from field observations and analysis results for potential improvement of the DLM performance are also presented in this paper.

Dynamic Late Merge Control at Highway Work Zones: Evaluations, Observations, and Suggestions

The purpose of this study is to present the evaluation result of a dynamic late merge (DLM) system for highway work zone operations, experimented by the Maryland State Highway Administration and International Road Dynamics Inc. The evaluation focuses mainly on the operational efficiency such as the input-output analysis, work zone throughput, volume distribution, and resulting queue length. Evaluation results reveal that a properly deployed DLM system can indeed outperform the conventional merge control with respect to the total work zone throughputs. Such a system, however, may result in excessive traffic conflicts if not properly integrated with existing static warning signs for work zone operations. Some suggestions and guidelines developed from field observations and analysis results for potential improvement of the DLM performance are also presented in this paper.

Adventures in Building Another Washington Monument: Rebid Outcomes of Woodrow Wilson Bridge Project

In December 2001, the Maryland State Highway Administration (SKA) opened a single bid for the substructure and superstructure contract to replace the Woodrow Wilson Memorial Bridge, the crossing of the Potomac River for I-95 and I-495 (Capital Beltway) traffic. This contract was part of the larger Woodrow Wilson Bridge project, a $2.5 billion project to build the new Potomac River crossing and to reconstruct the four interchanges in its vicinity. The contract’s estimate was a record for SHA at $487 million. The single bid was for a budget-wrecking $860 million and was rejected. The design team regrouped and focused its efforts on innovative means for bringing the project back on budget. Maryland SHA convened an independent review committee (IRC). Composed of industry experts, the IRC advised the design team on making the contract less expensive and more attractive to contractors to increase competition and reduce costs. Ultimately, the work was readvertised as three separate contracts. The outcome of redesigning and readvertising was to reduce the total bid amount for the work by $362 million. Several lessons were learned in handling megaprojects: reach out to the construction industry early and often to rouse and maintain interest in the project; make terms of the contracts as contractor friendly as reasonable; and, when sizing the contract, ensure that it is manageable and that it balances competition and contract interface risk.

Model to Analyze the Effectiveness of Highway Rest Area Performance

The number of highway travelers in the United States has significantly increased in the past decade. In light of this increase, proper maintenance of highway rest areas is very critical. This research examined the development of a rest area evaluation model that was created for the Maryland State Highway Administration (SHA) in response to its strategic plan for gauging rest area performance and allocating maintenance funds appropriately. To measure rest area performance, a customer-evaluation card was prepared for dissemination at Maryland's 14 rest areas. The card contained 14 questions, 13 of which had 5 grading options: A through D and N/A. In the 14th question, the rest area visitors were asked to provide written comments. SHA established as a strategic planning goal that a minimum of 80% of responses show a customer-satisfaction rating of B or above on each of the first 13 questions. The evaluated cards were routinely gathered and manually entered into a Microsoft Access database, which was then imported to a Microsoft Excel spreadsheet program for further evaluation. A number of array formulas were developed in Excel to automate the analyses. The model has been in place since 2000, and the data set has grown from over 1,000 initially in 2000 to over 6,000 as of July 2003. The model has been performing satisfactorily; however, manual entry of the data has been slow and error prone. Installation of touch screen information kiosks and increased sophistication in analyses were suggested as some future enhancement measures.

Implementation of Automated Network-Level Crack Detection Processes in Maryland

The Maryland State Highway Administration (MDSHA) has collected cracking data on its roadways for use in its pavement management system since 1984. Through much of this history the pavement cracking survey was performed yearly by teams of inspectors riding in vans. With the reengineering of the administration over the years, this process began to present serious resource and logistical problems. During the past 3 years, the MDSHA pavement management group has developed and implemented a state-of-the-art automated network-level crack detection process that is showing promising results. This process is based upon the use of the automated road analyzer (ARAN) data collection vehicle, Wisecrax crack detection software, and an intensive quality-control (QC) and quality-assurance (QA) procedure. The data collection and data processing tasks are all performed in house with MDSHA resources. An overview of the processes developed and implemented by MDSHA to conduct these surveys is provided. Also discussed are challenges and lessons learned during the implementation process. Presentation of this information will allow others to gain insight into the strengths and weaknesses of adopting such a system and promote information sharing among pavement data collection organizations. Overall, it is concluded that automated network-level crack detection is a workable and efficient tool. However, a strict QC-QA regime must be instituted in order to achieve consistent and repeatable results.

Implementation of New Ride Quality Specification in Maryland: Incentive-Based Profile Specification

The Maryland State Highway Administration (MDSHA) has developed a new, performance-based construction specification for ride quality. The new specification was developed as a strategy to meet an objective in the MDSHA business plan that requires the percentage of smoother pavements to increase statewide over the next 5 years. The new specification allows the use of inertial profiler testing devices as well as California-style rolling-wheel profilographs and includes incentive- and disincentive-based pay adjustments for asphalt paving. The specification includes an innovative approach to establishing acceptable ride quality values that considers many of the factors that affect the ability to construct a smooth riding surface. In addition, the specification includes clear identification of pay adjustments that are calculated using a software application developed by MDSHA. The new specification is to be included in all projects advertised after July 1, 2001, and implementation involves efforts to train construction project personnel in the use of the specification. Future implementation efforts phase out the use of the California-style profilograph by 2004. The efforts completed to date to develop the new specification are described, and highlights of the new specification are provided.