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Current Projects

 

Handling Lead and Asbestos Issues in Bridge Construction and Maintenance

TxDOT FY 2007

Research Supervisor: Audra Morse

The goal of this research was to survey the state of the regulatory environment and common practices in other state DOTs to learn how other states deal with the issue of lead-based paint and asbestos-containing materials in bridge maintenance and repair for the state’s 50,000 existing bridges. The survey included 40 questions to all 50 state DOTs, with 39 responding.  The survey responses were evaluated to formulate primary recommendations intended to decrease TxDOT liability in the short term.  Among the primary recommendations were to train TxDOT personnel on appropriate OSHA regulations, limit TxDOT worker exposure to hazardous materials, and establish oversight of contractor controls and safety protocols.  The study also led to several secondary recommendations designed to limit TxDOT liability in the long term, such as conducting a study of all bridges to determine the exact location, quantity, and nature of both LBP and ACM, conduct a study of ambient air monitors to measure airborne lead concentrations, and determine the economics of encasing ACM and LBP wastes in concrete.

 

Public Transportation Maintenance Knowledge and Resource Sharing Project

TxDOT FY 2007

Research Supervisor: Mario Beruvides

Poor maintenance practices and a lack of mechanical expertise result in an aging and undependable fleet for transit systems.  The lack of local maintenance expertise is especially severe in rural parts of Texas.  In response to this problem, this project examined several approaches to regional public transportation maintenance efforts in the Texas rural transportation system.  “Hub” areas, or centralized locations with traffic from several surrounding communities, were examined and found to be the ideal first choice for a regional maintenance center (RMC). Initial guidelines for Standard Operating Procedures were categorized and facility-sharing approaches were investigated  Among other findings of this study, it was determined that RMCs with a training center for mechanics and drivers could be the solution to more effective vehicle maintenance and performance in rural transit systems. 

 

Operation and Management of the Traffic Management Center

City of Lubbock, FY 2007-2010

Research Supervisor: Hongchao Liu

A Traffic Management Center is the nerve center of most freeway management systems. It collects and processes highway system data and provides useful information to the traveling public as well as other agencies. TMC systems play a significant role in managing daily traffic in metropolitcan areas. In partnership with TechMRT's TransTech program, the City of Lubbock is installing ts first TMC. This project helps the City Traffic Operation's office monitor the operation of the highway systems and coordinate their responses to traffic situations and incidents.

Live Load Testing of Sandwich Panel System Bridges

TxDOT IAC

Research Supervisor: Charles Newhouse

This new project focuses on live load testing to be performed to validate design assumptions and to provide a baseline for long-term performance of the experimental bridge. The testing will take place in Wise County.

Corridor Traffic Analysis for South Loop 289

TxDOT, 2007-2008

Research Supervisor: Hongchao Liu

The Loop 289 Corridor within the project limits is a rapidly developing area with heavy commercial development adjacent to the facility. South and West Loop 289 carry more traffic than any other freeway in the Lubbock region. Operational problems along the corridor include peak-hour main-lane congestion, weaving problems between access points, frontage road congestion and increased accident frequency. Phase 1 of this project focuses on modeling the mainlanes, ramps and frontage road and conducting a comprehensive examination and evaluation of lane configurations, addition of auxiliary lanes and ramp configurations. TechMRT will develop a number of alternatives that can be evaluated for further consideration. Phase 2 of the project consists of a more detailed modeling of the Loop 289 frontage roads and the intersections at Loop 289 and Quaker Avenue, and Loop 289 and FM 1730. The final product of this research will be an analysis of the optimal configurations that could be implemented along the corridor, as well as strategies to incorporate elements for intelligent transportation highway systems (ITS) as deemed appropriate.

 

Guidance for Design in Areas of Extreme Bed-Load Mobility

TxDOT, 2004-2008

Research Supervisor: Ken Rainwater

A recurring problem for TxDOT involves low-water crossings and other low-height structures that cross streams within the Edwards Plateau (Hill Country) region of central Texas. These crossings are often subject to large or even catastrophic flood flows. The flows typically exhibit high velocities, and a large concomitant flux of gravel and cobble-size bed load. This bed load often covers or buries low-water crossings, damages structures, and contributes to partial or complete failure of structures. Often roadways after floods become impassable or hazardous to public travel and restrict the activities of emergency services until TxDOT maintenance crews are able to clear crossings and make necessary repairs or even structural replacement. This multi-institution six-year research project is intended to document the geographic extent of this problem, physical causes (natural and otherwise), and suggest mitigation efforts or design changes that TxDOT engineers can implement for cost-effective, risk-mitigating stream crossings in the affected area.

 

Comprehensive Planning and Design Guidelines for Bus Rapid Transit Design on Texas Highway Corridors

TxDOT, FY 2006-2008

Research Supervisor: Hongchao Liu

This research is being performed in collaboration with the Unversity of Texas at Austin and University of Texas at El Paso. Many corridors in the Texas State highway system face increasing congestion while having severe right-of-way limitations. The best form of congestion relief may not be additional highway lanes and/or grade separations. The best solution may be introduction of a higher-capacity transit system. Bus Rap Transit (BRT) is increasingly regarded as a cost-effective solution for improving mobility and alleviating congestion in urban transportation networks. This research is aimed at providing TxDOT with comprehensive guidelines for planning and designing BRT that will allow development for a BRT scenario in the traditional alternatives analysis.

 

Evaluating Existing Culverts for Load Capacity Allowing for Soil Structure Interaction

TxDOT FY 2008-2009

Research Supervisor: William Lawson

When rights-of-way crossing existing culverts have to be raised and/or widened, the culverts must be reanalyzed. Using current analysis methods (direct stiffness) and AASHTO loading protocols often results in these culverts being judged deficient, with a requirement for replacement or retrofit. The puzzling thing is that even very old box culverts very rarely fail in service, and when they do show distress it's not in the same form as the current analysis methods would predict. This indicates that the direct-stiffiness method is too conservative, and not representative of soil-structure interaction. It is not accurate enough in representing either the way the soil loads the structure, or the percentage of load that the soil itself absorbs. This research will find the best way to approach this situation through use of finite element analysis to model the soil-structure system, calibrate the analytical model by using heavy vehicles to apply lane loads to existing culverts, and measure strain and deflection in the walls and slabs, perform parametric analyses to calculate actual culvert structural loads over a range of culvert structures and geometries, fill heights and characteristics, and develop rational load ratings for culverts by applying the reserve capacity determined through the parametric finite element studies to the demand calculated by direct stiffness.

 

Develop Statewide Regression Equations for Improved Flood Peak Estimation

TxDOT FY 2007-2009

Research Supervisor: Ken Rainwater

The estimation of peak-streamflow frequency for ungaged streams is an important component of infrastructure design conducted by TxDOT. Peak-streamflow frequency represents the collective peak streamflow for recurrence intervals of 2, 5, 10, 25, 50, 100, 250, and 500 years. A popular technique for estimation of peak-streamflow frequency is based on the regional regression method. The regression equations are developed through the statistical relations between watershed characteristics and site-specific T-year peak streamflow values derived from U.S. Geological Survey streamflow-gaging stations. Watershed characteristics for the ungaged location are used with the T-year regional regression equation to estimate the T-year peak streamflow. A project is proposed to further refine the regional regression equations using state-of-the-practice techniques with the purpose of enhancing cost-effective, risk-mitigated design for hydraulic structures by TxDOT. The resulting equations will complement existing techniques in use by TxDOT engineers.

 

Design Procedures for MSE/Soil Nail Hybrid Retaining Wall Systems

TxDOT FY 2005-2008

Research Supervisor: Priyantha Jayawickrama

The use of hybrid (MSE/soil nail) retaining wall construction can, in certain situations, result in greater economy and efficiency of construction. The configuration consists of an excavation to emplace the soil nails, with the MSE wall placed on top and backfilled. Currently, the design approach that has been taken is to design both the MSE and soil nail wall to the full projected wall height. This is clearly not an economical approach, nor does it address the specific force-transfer mechanism inherent in the hybrid wall. This research will produce a set of design guidelines for hybrid walls, with examples. Construction guidelines will be formulated.

 

Hydraulic Performance Evaluation of Horizontel Inlet Type H

TxDOT FY 2007-2009

Research Supervisor: Ken Rainwater

Type H Inlets are frequently used by TxDOT as median drains for divided highways. Two varieties of Type H inlets are used - the Horizontel Inlet (Type H) with grate top and the the Horizontel Inlet (Type H) with lid, both illustrated in TxDOT construction details IL-H-G and IL-H-L. Despite frequent use, engineers do not have adequate design information to mathematically describe the hydraulic performance of these structures. Typically, it has been assumed that IL-H-G and IL-H-L function essentially the same as roadway grates or curb inlets. This project will evaluate the hydraulic performance of the Horizontel Inlets (Type H) through physical testing, and to synthesize the results of that testing into a series of algorithms for design use.

 

Develop a New Testing and Evaluation Protocol to Assess Flexbase Performance using Srength of Soil Binder

TxDOT FY 2007-2008

Research Supervisor: Priyantha Jayawickrama

This research study will examine the applicability and potential implementation of the Merrick Flexometer test procedure for characterizing flexible base, treated base and treated subgrade materials. This new test method has been developed by the Snyder Area Office of TxDOT's Abilene District for evaluating base and subgrade materials based on the flexural strength of the binder portion (.i.e. portion passing No. 40 sieve) of that material. The new test method offers a number of advantages that include the small quantity of material needed for testing, and the quick turn around time - a total of five days for sampling, testing and reporting. This research will perform a thorough and systematic evaluation of the new flexometer test method with the eventual goal of developing a reliable and repeatable test protocol that could be used as a quality control tool for flexible base, treated base and treated subgrade materials. Other aspects investigated include the limits of applicability of the flexometer test, repeatibility and test method validation through cross-correlation of flexometer test results with data obtained from other, more established test methods.

 

Development of Field Performance Evaluation Tools and Program for Pavement Marking Materials

TxDOT FY 2007-2010

Research Supervisor: Texas Transportation Institute

Hongchao Liu is collaborating with the Texas Transportation Institute and Texas A&M at College Station for this project that will develop field performance-based evaluation procedures for pavement marking materials (PMMs). Field decks are expected to be designed incorporating regular long lines together with transverse stripes for accelerated testing. Field decks will be installed at selected locations in the state considering area climate, roadway surface type, and traffic condition.Carefully selected PMM products will be installed and monitored for their field performance over time. Field test results will be used to correlate with initial specifications to develop new performance-based specifications. At the end of the project, a field performance database that can record and query all relevant data, track individual jobs and products, graphically display performance changes over time, and predict future performance of PMMs will be developed for TxDOT use.

 

Subdivision of Watersheds for Modeling

TxDOT FY 2007-2008

Research Supervisor: Ken Rainwater

After delineation of a watershed, a decision about the internal treatment of the watershed is required. The question is, "Should the watershed by subdivided into sub-watersheds?" The idea is that a watershed should be subdivided if, and only if, justification exists for the additional complexity in the modeling that follows the delineation/subdivision. Good reasons for subdividing a watershed do exist, such as differences in sub-watershed basin characteristics (length of main channel, etc.) the presence of regulating structures (reservoirs or dams), or the professional judgement of the analyst that subdivision is required for proper representation of model parameters. The intent of this research is to address the lack of watershed subdivision guidance through the execution of a series of research tasks. In addition, a review of the state-of-the-practice of distributed hydrologic modeling is to be conducted. The objectives are to develop a set of defensible guidelines for watershed subdivision and provide guidance for application of distributed hydrologic models to enhance the design process within TxDOT.

 

Transport Spill Containment for Texas Highways

TxDOT 2007-2009

Research Supervisor: Audra Morse

Substantial amounts of hazardous materials are transported over Texas highways. Given the number of transport vehicles transversing the highways, a finite risk of a vehicular accident and subsequent release of hazardous materials exists. One of the tasks of first-responders to an accident involving a transport vehicle is to determine if hazardous materials are present, and if so, to request personnel with specific training to take measures to prevent migration of spilled materials into sensitive receiving waters. Although quantities are substantially smaller, a similar issue of spill containment arises with loss of vehicular fluids in an accident. This research will develop guidelines for the selection and design of appropriate spill containment structures that could be included with new construction, or as a retrofit for existing locations.

 

Study of Elastomeric Bearings for Superelevated U-Beam Bridges

TxDOT FY 2008-2009

Research Supervisor: Charles Newhouse

Elastomeric bearings are currently used by TxDOT to transfer load from the state's standard Texas U-beam section to the substructure. Designers usually refer to a set of TxDOT standard sheets to detail the bearings. The standard details for the bearings seem to work well when the U-beams are placed with little or no superelevation. However, when the beams are placed on a significant superelevation, the transverse thrust due to the deal weight of the beams can cause a transverse shear deformation at the time the beams are placed. This research is designed to address two basic issues: first, are the transverse shear deformations, either alone or in combination with the normally expected thermally induced shear deformations, significant enough to be considered in design, and secondly, if the transverse shear deformations are significant, how should they be considered in design?