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There have been considerable research efforts conducted, in recent years, at local and national levels to investigate the effect of material characteristics as well as design techniques on the performance of chip seals. In addition, with the advancement of technology, new materials and additives have been introduced into the construction market with the goal of enhancing the performance of chip seals. Despite these advances, and the long history of chip seal use on its roadway network, the Virginia Department of Transportation (VDOT) has not undertaken a thorough review of its chip seal practices in more than 25 years. The objective of this research study will be to evaluate VDOT’s single layer (single layer and modified single layer) chip seal practices from a materials characterization and design perspective.

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Mass concrete elements are usually heavily reinforced and subject to large thermal change as the concrete cures.  The definition of mass concrete is generally based on the minimum dimension of the element but is more complicated because of the many factors involved.  High heat retention in mass concrete causes differential and high temperatures that can result in detrimental cracks.  In some applications of mass concrete, high strengths or early strengths are needed, requiring increases in cementitious material contents beyond the usual low amount of cementitious materials needed in mass concrete to keep the temperature from rising too high during cement hydration.  Typically, concretes with regular consistency measured by slump test are used in mass concrete elements.  However, congestion of the reinforcement in the element combined typically with geometric and placement constraints require concretes with high flow rates, as in self-consolidating concrete (SCC).  Such concretes generally have high cementitious material contents for flowability and stability.  There is a conflict in the amount of cementitious materials between mass concrete which requires low cementitious contents to control temperature rise and the use of high cementitious contents for early or high strengths and high workability.  The cementitious material contents include supplementary cementitious materials, fly ash and slag cement, for durability and to reduce portland cement contents for temperature control. The objective of this study is to investigate and optimize mass concrete mixtures with regards to temperature control and high workability.  Also, the definition of mass concrete will be refined in ways that are helpful to VDOT in taking precautions to avoid problems that can arise during placement and curing.

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The Virginia Department of Transportation (VDOT) is operating a variable speed limit (VSL) system on I-95 northbound between mileposts 115 and 130, south of Fredericksburg.  The goal of the VSL system is to improve both safety and operations on this congested section of highway by encouraging speed harmonization, more uniform speed selection, dampening the effects of shockwaves, and providing advance warning of congestion. This project will continue the evaluation of the safety and operational impacts of the VSL system to determine benefits during the first year of operations.  Performance measures will include changes in crashes, travel time reliability, delay, throughput, and speed compliance.  The overall benefit-cost ratio of the system will be examined as well.

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The Virginia Department of Transportation (VDOT) currently requires the use of the Indirect Tensile Cracking Test (IDT-CT) as specified in ASTM D8225-19 in its Balanced Mix Design (BMD) specification to assess the cracking susceptibility of dense-graded asphalt surface mixtures (SM) with “A” (PG64S-22) and “D”(PG64H-22) designations (i.e., 0 to 3 million equivalent single axle load [ESAL] range for A mixtures and 3 to 10 million ESAL range for D mixtures). A current performance criterion requiring a minimum cracking tolerance (CT) index of 70 was recommended to alleviate the cracking susceptibility of the asphalt mixtures based on extensive mixture testing. This CT index was determined based on testing of compacted specimens from reheated plant-produced asphalt mixtures. Although the current cracking testing protocol and its threshold value (i.e., CT index of 70) in VDOT’s BMD specification is indicative of the cracking performance of asphalt mixtures, it does not account for how the performance of asphalt mixtures throughout the service life is affected by oxidative aging (i.e., as it experiences long-term aging). Thus, laboratory evaluation of the long-term oxidative aging characteristics of asphalt mixtures is essential to ensure that the asphalt mixtures within the pavement structures continue to perform adequately throughout their service life. The objective of this research is twofold: (I) to develop practical long-term aging protocols for asphalt SMs with A and D designations that can be used in mix design verification and production of asphalt mixtures for quality control and acceptance purposes; and (II) to develop preliminary performance criteria for CT index for the to-be-developed long-term aging protocols. 

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VDOT seeks to explore how to enhance its capability to anticipate threats to system level service and customer mobility, namely flood impacts on transportation assets.

Through an environmental scan, VDOT will be able to understand such existing operational and emergency management systems being used by other DOTs and MPOs to provide resilience in their transportation network. Alongside the scan, this effort will document VDOT's flood threat monitoring, assessment, and response needs from an operational perspective.

Objectives:

• Provide VDOT with an understanding of current state of the practice for forecasting flood impacts at transportation assets, with peer DOT organizations.
• Systematically solicit and compile requirements for a flood warning capability from a representative cross-section of VDOT District and HQ operations, maintenance, and emergency management staff.
• Using state of the practice information gathered and VDOT requirements develop a summary recommendation.

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Routine inspections as per National Bridge Inspection Standards regulations provide rough estimates of bridge deck conditions at least every 24 months. Being primarily visual, this information does not provide in-depth information needed for maintenance decisions. So, when severe deterioration is suspected, more extensive inspection approaches are pursued. However, very little guidance exists for when to trigger further inspection and what methods to employ. In addition, rapid growth in technology has made available several affordable non-destructive evaluation techniques with reduced traffic impacts. Similarly, no guidance exists on when to apply them and what value they can provide. This study seeks to develop a methodology to improve routine inspections for consistency, evaluate available technologies to better inform inspection strategies, and develop a preliminary data-driven framework for decision-making regarding bridge inspection levels.

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This is the third phase of research designed to implement pavement friction management (PFMP) with the goal of minimizing crash-related fatalities and serious injuries.  This final-phase project will provide the transitional support necessary for a statewide deployment of the developed safety analysis and treatment recommendation framework as documented in the Phase 1 and 2 reports. Phase 3 will work with the data collected in Phase 2 in each District and involve: further demonstrating the technology; uploading the data collected to the pavement management system (PMS); training the district personnel on the use of the data; and developing written guidelines for implementing project-level and network-level CFM. 

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Truck travel time reliability (TTTR) is one of the most important performance measures for assessing freight movement on the interstates. The Virginia Department of Transportation (VDOT) and the Office of Intermodal Planning and Investment (OIPI) have been reporting TTTR as required by the FHWA and using TTTR in various project planning and performance measurement processes. They are interested in data-driven approaches to identify the locations and causes of unreliable truck travel times and to predict TTTR metrics. This study will address the research needs by developing a systematic method to identify the location, time period, and causes of unreliable truck travel times, and develop models to predict TTTR.   

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Since the early 1980’s, the Virginia Department of Transportation (VDOT) has been developing, evaluating, modifying, and incorporating bridge abutments that eliminate deck joints. More than 35 years later, VDOT’s Structure and Bridge Division has asked the Virginia Transportation Research Council to assess the performance of the various jointless abutments by visiting a representative sample of bridges constructed with these abutment and approach types. The goal of this project will be to assess the effect of various geometrical parameters on the long-term performance of various jointless abutments. This study may serve as the first in a potentially multi-phase effort that, ultimately, could expand the number of new bridges that can be constructed using more economical jointless abutments and approaches that also lead to lower life-cycle costs and fewer disruptions to the traveling public.

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Cracking of concrete bridge decks is detrimental to the service life of bridge infrastructure. Multiple factors affect bridge deck cracking including material properties, construction techniques, structural design, and environmental conditions. To enhance construction productivity, contractors in the state of Virginia have requested VDOT to allow for continuous placement of bridge decks, instead of the recommended segmental/checkerboard placement technique in which positive moment sections are casted first. While a preliminary literature review suggests that continuous placement of bridge decks increases the likelihood of cracking due to greater tensile stress development, VDOT engineers are uncertain whether this practice could significantly exacerbate bridge deck cracking, leading to a reduced service life of the bridge structure. As a response, the purpose of this study is to: (1) perform an in-depth literature review on the subject; (2) conduct a survey among state DOTs and VDOT districts to gather their collective knowledge and experience on the impact of bridge deck placement techniques on deck cracking performance; and (3) recommend placement methods to minimize cracking.

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Detour routes are often set up by agencies to address both planned (e.g., major roadway maintenance) and unplanned (e.g., traffic incidents, adverse weather, and natural disaster) events.  A successful detour operation depends on carefully designed detour routes, timely activation of detour, and clear communication to drivers. Sometimes, the detour operations require additional time and labor resources to set up temporary detour signs along the detour route, which could delay the activation of detour operation. To improve traffic incident response, the Staunton District of Virginia Department of Transportation planned to test the use of MUTCD-approved permanent emergency routing signs on the I-81 corridor. This study aims to estimate the potential benefit of using permanently-installed emergency routing signs in detour operations, and to explore the impact of these signs on traffic diversion during detour operations under a full closure of I-81 as well as voluntary detours during partial lane closure incidents. The results are expected to provide insights for VDOT to improve incident response and detour operation practices.

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This study will focus on the lightweight soundwall panels, and the structural components associated with them that are often mounted on bridges but can also be found adjacent to a roadway.  While it is common for these panels to be metallic, other materials have also been used by VDOT.  Therefore, it is expected that some of the lightweight soundwall panels may be more durable than others.  

Since VDOT is the owner of these soundwall panels,    VDOT must also maintain them when they degrade and need to be repaired.  Therefore, the relative durability of the different soundwall panels is important to VDOT because more durable soundwall panels will decrease maintenance costs for the Department.  To better understand the relative durability of lightweight soundwalls in Virginia, a research effort to study this question was proposed.    

The research study discussed herein proposes to perform field evaluations to assess the general condition of lightweight soundwall panel systems.  This study will capture condition data for various types of soundwall systems located throughout Virginia to determine if there are any features that contribute to greater durability.  Data  will be gathered on the materials used, the condition of the soundwall panels, and any visual damage to the structural components.  This information will be shared, and recommendation will be made in the VTRC final report.    

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