Digest1002

Research Digest FORWARD ALL REQUESTS TO: The University of Texas at Austin Center for Transportation Research LIBRARY 3208 Red River • Suite 115 • Austin • Texas • 78705-2650 Phones: (512) 232-3126 and (512) 232-3138 • Fax: (512) 232-3088 Email: ctrlib@uts.cc.utexas.edu

In this Issue: TxDOT Reports

Table of Contents Item 1. Effects of Wet Mat Curing Time and Earlier Loading on Long-Term Durability of Bridge Decks: Fracture, Flexural Strength and Shrinkage (TechMRT 2116-4B) ................................................................ 1 Item 2. Proposed Modifications to the LRFD Design of U-Beam Bearings (TechMRT 5834-P1) ............. 1 Item 3. Utility Installation Review System - 2008 Follow-up Report (TTI 2110-03-4) ............................. 2 Item 4. Effect of Voids in Grouted, Post-Tensioned Concrete Bridge Construction: Volume 1 Electrochemical Testing and Reliability Assessment (TTI 4588-1 Vol. 1) .................................................. 3 Item 5. Effect of Voids in Grouted, Post-Tensioned Concrete Bridge Construction: Volume 2 Inspection, Repair, Materials, and Risks (TTI 4588-1 Vol. 2) ..................................................................... 4 Item 6. Effect of Voids in Grouted, Post-Tensioned Concrete Bridge Construction: Inspection and Repair Manual for External Tendons in Segmental, Post-Tensioned Bridges (TTI 4588-2) ................................... 5 Item 7. Corrosion Performance Tests for Reinforcing Steel in Concrete: Technical Report (TTI 4825-1). 5 Item 8. Corrosion Performance Tests for Reinforcing Steel in Concrete: Test Procedures (TTI 4825-P1). 6 Item 9. Field Manual for the Operation of Advanced Warning of End of Green System (AWEGS) (TTI 5113-01-P1)……….…………………………………………………………………………………...6 Item 10. Mechanistic-Empirical Asphalt Overlay Thickness Design and Analysis System (TTI 5123-3) 7 Item 11. Operating Guidelines for TxDot Ramp Control Signals (TTI 5294-P1) ....................................... 8 Item 12. Evaluating and Improving Incident Management Using Historical Incident Data: Case Studies at Texas Transportation Management Centers (TTI 5485-1) ........................................................................... 8 Item 13. Assessment of a Traffic Monitoring System for a Major Traffic Generator to Improve Regional Planning: Technical Report (TTI 5531-2) .................................................................................................... 9 Item 14. Delivery of Workshops on Mobility Monitoring in Small to Medium-Sized Communities (TTI 5571-01-1) ........................................................................................................................................... 9 Item 15. Performance Evaluation of Cable Median Barrier Systems in Texas (TTI 5609-1) ................... 10 Item 16. Potential Development of an Intercity Passenger Transit System in Texas-Report on Tasks 1-5 (TTI 5930-1) ................................................................................................................................................ 10 Item 17. Considerations for Rigid vs. Flexible Pavement Design when Allowed as Alternate Bids: Technical Report (TTI 6085-1) .................................................................................................................. 11 Research and Technology Implementation Office February 2010

Research Digest Item 1 Effects of Wet Mat Curing Time and Earlier Loading on Long-Term Durability of Bridge Decks: Fracture, Flexural Strength and Shrinkage TEXAS TECH UNIVERSITY (TECHMRT) TechMRT 2116-4B • 2009 There is increasing pressure from owners, contractors, and the public to open bridge decks sooner to full traffic loads. As a result, a set of criteria or guidelines is needed to determine when concrete bridge decks can safely be opened.

Full-text PDF of this report is available for free download from http://www.depts.ttu.edu/techmrtweb/Reports/Complete%20Reports/2116-R4B_final.pdf

Item 2 Proposed Modifications to the LRFD Design of U-Beam Bearings TEXAS TECH UNIVERSITY (TECHMRT) TechMRT 5834-P1 • 2009 Chapter 3: Superstructure Design Section 6 - Prestressed Concrete U Beams (Types U40 and U54) Full-text PDF of this report is available for free download from http://www.depts.ttu.edu/techmrtweb/Reports/Products/0-5834-P1.pdf

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Research Digest Item 3 Utility Installation Review System - 2008 Follow-up Report TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 2110-03-4 • 2009 In December 2007, the Texas Department of Transportation (TxDOT) received delivery of a web-based system that automates the submission, review, approval, construction, and archival of utility installation request at TxDOT. The system, called Utility Installation Review (UIR), enables users to submit and process installation requests online, including supporting documentation such as design and construction drawings. The system also includes an online geographic information system (GIS)-based interface that enables users to locate and query proposed installation requests using an interactive map. The system includes tabular and GIS-based reporting options.

This report summarizes the work completed in 2008. The original intent for this year was to conduct research implementation activities in three main areas: (a) maintain UIR software and conduct knowledge transfer based on user feedback and needs, (b) assist TxDOT with the statewide UIR training program, and (c) provide technical support to district and utility company users. As of December 2007, five TxDOT districts were online: Bryan, Fort Worth, Houston, Pharr, and San Antonio. At the beginning of 2008, TxDOT decided to postpone the statewide implementation of UIR until appropriate funding using an interagency agreement could be identified to support that effort. As a result, the researchers' focus in 2008 was to maintain the UIR software, conduct knowledge transfer, and provide technical support to district and utility company users in the five districts where UIR was active. This report summarizes these activities.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/5-2110-03-4.pdf

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Research Digest Item 4 Effect of Voids in Grouted, Post-Tensioned Concrete Bridge Construction: Volume 1 - Electrochemical Testing and Reliability Assessment TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 4588-1 Vol.1 • 2009 Post-tensioned (PT) bridges are major structures that carry significant traffic. PT bridges are economical for spanning long distances. In Texas, there are several signature PT bridges. In the late 1990s and early 2000s, several state highway agencies identified challenges with the PT structures, mainly corrosion of the PT strands.

The Texas Department of Transportation (TxDOT) performed some comprehensive inspections of its PT bridges. A consultant’s report recommended that all ducts be re-grouted. However, the environment in Texas is very different than the environments in which the corrosion of the PT strands were observed. The objective of this research was to evaluate the corrosion activity of strands for PT structures and to correlate this corrosion activity with general environmental and void conditions. To achieve this objective, time-variant probabilistic models were developed to predict the tension capacity of PT strands subjected to different environmental and void conditions. Using these probabilistic models, time-variant structural reliability models were developed. The probability of failure of a simplified PT structure subjected to HS20 and HL93 loading conditions was assessed.

Both flexural failure and serviceability were assessed. Results indicate that the presence of water and chlorides can lead to significant corrosion rates and failure is dependent on this corrosion activity and the number of strands exposed to these conditions. Volume 1 of this report presents these results. To assist TxDOT with developing a plan to mitigate this corrosion, studies were performed to assess repair grout materials, inspection methods, and repair methods. In addition, a general methodology is presented on optimizing repairs. These topics are presented in Volume 2 of this report. An Inspection and Repair Manual was also developed from this research and is presented in a separate report. Results indicate that TxDOT should prevent water and chlorides from infiltrating the tendons; this can be achieved in part by repairing drain lines and ducts and protecting anchor heads, as these conditions can lead to early failure of PT bridges. Recommendations on inspections, repairs, and materials are provided; however, further research on the potential formation of galvanic coupling of strands embedded in both existing and new repair grouts needs to be assessed.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-4588-1-Vol1.pdf

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Research Digest Item 5 Effect of Voids in Grouted, Post-Tensioned Concrete Bridge Construction: Volume 2 - Inspection, Repair, Materials, and Risks TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 4588-1 Vol.2 • 2009 Post-tensioned (PT) bridges are major structures that carry significant traffic. These bridges are designed and constructed because they are economical for spanning long distances. In Texas, there are several signature PT bridges. In the late 1990s and early 2000s, several state highway agencies identified challenges with the PT structures: mainly corrosion of the PT strands. The Texas Department of Transportation (TxDOT) performed some comprehensive inspections of their PT bridges. A consultant’s report recommended that all ducts be regrouted. However, the environment in Texas is very different than the environments in which the corrosion of the PT strands were observed. The objective of this research was to evaluate the corrosion activity of strands for PT structures and to correlate this corrosion activity with general environmental and void conditions. To achieve this objective, timevariant probabilistic models were developed to predict the tension capacity of PT strands subjected to different environmental and void conditions. Using these probabilistic models, time-variant structural reliability models were developed. The probability of failure of a simplified PT structure subjected to HS20 and HL93 loading conditions was assessed. Both flexural failure and serviceability were assessed. Results indicate that the presence of water and chlorides can lead to significant corrosion rates and failure is dependent on this corrosion activity and the number of strands exposed to these conditions. These results are presented in Volume 1 of this report. To assist TxDOT with developing a plan to mitigate this corrosion, studies were performed to assess repair grout materials, inspection methods, and repair methods. In addition, a general methodology is presented on optimizing repairs. These topics are presented in Volume 2 of this report. An Inspection and Repair Manual was also developed from this research and is presented in a separate report.

Results indicate that TxDOT should prevent water and chlorides from infiltrating the tendons — this can be achieved in part by repairing drain lines, ducts, and protecting anchor heads as these conditions can lead to early failure of PT bridges. Recommendations on inspections, repairs, and materials are provided, however, further research on the potential formation of galvanic coupling of strands embedded in both existing and new repair grouts need to be assessed.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-4588-1-Vol2.pdf

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Research Digest Item 6 Effect of Voids in Grouted, Post-Tensioned Concrete Bridge Construction: Inspection and Repair Manual for External Tendons in Segmental, Post-Tensioned Bridges TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 4588-2 • 2009 Segmental, post-tensioned (PT) bridges are major structures that carry significant traffic. These bridges are designed and constructed because they are economical for spanning long distances. In Texas, there are several signature PT bridges. In the late 1990s and early 2000s, several state highway agencies identified challenges with the PT structures, mainly corrosion of the PT strands. The Texas Department of Transportation (TxDOT) performed some comprehensive inspections of their PT bridges. A consultant’s report recommended that all ducts be re-grouted. However, the environment in Texas is very different than the environments in which the corrosion of the PT strands was observed in the other bridges. Report 0-4588-1 summarized the research findings from a comprehensive study on the corrosion characteristics, reliability, materials, and repair for PT bridges. This document, an inspection and repair manual, was developed from information from this research program. This document provides an efficient approach to inspect and repair PT bridges. However, it should be noted that in this manual, repair does not include filling the voids in the tendons with grout. A recent failure of a tendon in a bridge in Virginia was suspected of being caused by repair grouting of the tendon, possibly due to the formation of a galvanic couple between the new repair grout and the original grout. Although a procedure for pressure-vacuum grouting of tendons is provided in Appendix A of this manual, this method should not be used until the potential issue associated with galvanic corrosion of the strands after repair is resolved.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-4588-2.pdf

Item 7 Corrosion Performance Tests for Reinforcing Steel in Concrete: Technical Report TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 4825-1 • 2009 The existing test method used to assess the corrosion performance of reinforcing steel embedded in concrete, mainly ASTM G 109, is labor intensive, time consuming, slow to provide comparative results, and can be expensive. However, with corrosion of reinforcement a major challenge to the durability of infrastructure systems, improvements in the corrosion performance of materials could add significant value. With limited resources, new procedures and test methods are needed to assess corrosion performance of potentially valueadding materials. This research evaluated four accelerated test procedures (rapid macrocell (a.k.a. minimacrocell), ACT test, CCIA test, and a modified ASTM G109 test) and compared these tests with the standard ASTM G 109 tests. The reasonableness of the test results, test simplicity, test cost, and test duration were all assessed. Results indicate that the rapid macrocell, ACT, and CCIA tests can reduce the time required to perform the tests by approximately 90 percent compared to standard ASTM G 109 test. Not considering the one-time equipment cost, the rapid macrocell, ACT, and CCIA decrease the cost by approximately 75, 58, and 67 percent compared to the standard ASTM G 109 test, respectively. The rapid macrocell test was determined to be relatively simple while the CCIA and ACT tests were considered to be more complex to perform. Based on the research findings, it is proposed that TxDOT use the rapid macrocell test to evaluate the corrosion performance of most materials. To evaluate the performance of dielectric coatings on reinforcement, it is recommended that the MG 109 test be used to evaluate these system types. For specific testing needs, other tests may be appropriate.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-4825-1.pdf _____________________________________________________________________________________________ Research and Technology Implementation Office February 2010 Page 5

Research Digest Item 8 Corrosion Performance Tests for Reinforcing Steel in Concrete: Test Procedures TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 4825-P1 • 2009 The existing test method to assess the corrosion performance of reinforcing steel embedded in concrete, mainly ASTM G109, is labor intensive, time consuming, slow to provide comparative results, and often expensive.

However, corrosion of reinforcement is a major challenge to the performance and long-term durability of infrastructure systems. Improvements in the corrosion performance of materials could add significant value to the infrastructure. New procedures and test methods are needed to assess the corrosion performance of potentially value-adding materials. This study evaluated four accelerated test procedures: the mini-macrocell (MM) test, the concrete chloride ion assessment (CCIA) test (also referred to as the concrete corrosion inhibitor association test), the accelerated chloride threshold (ACT) test, and the modified G109 test. Results from the accelerated tests were compared with results from the standard ASTM G109 results. The rapid MM test proved to be relatively simple, and researchers recommend that it be used to assess the relative performance of several material systems. The CCIA and ACT tests are recommended only when the critical chloride threshold of a reinforced system is needed. These tests are more complex and expensive to perform than the MM test. This product provides the procedures for performing these tests. The modified G109 test can continue to be used, but test durations are still relatively long.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-4825-P1.pdf

Item 9 Field Manual for the Operation of Advanced Warning of End of Green System (AWEGS) TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 5113-01-P1 • 2009 The objective of this implementation project was to implement four AWEGS across Texas at intersections appropriate for the installation of AWEGS. After a survey across Texas, four sites were chosen in the Atlanta District, Pharr District, Odessa District, and San Antonio District. The AWEGS design plans were prepared for these four sites and submitted to the districts. These design plans were prepared for an intersection with highspeed approaches having the required dilemma zone detection design. The Atlanta District implementation was typical of the earlier implementation and used the TS-2 TS-1 conversion panel. However, the remaining implementations were configured for using enhanced BIUs. AWEGS software was also modified to account for rail preemption as the site in the Odessa District was being preempted by between 15 to 25 trains per day. Finally the implementation in the San Antonio District was redesigned to use radar detection for both dilemma zone and advance detection. AWEGS at the Atlanta, Pharr, San Antonio, and Odessa Districts have been implemented, and an evaluation of the system showed that AWEGS was performing satisfactorily at all sites.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/5-5113-01-P1.pdf

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Research Digest Item 10 Mechanistic-Empirical Asphalt Overlay Thickness Design and Analysis System TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 5123-3 • 2009 The placement of an asphalt overlay is the most common method used by the Texas Department of Transportation (TxDOT) to rehabilitate existing asphalt and concrete pavements. The type of overlay and its required thickness are important decisions that TxDOT engineers make on a daily basis. To perform well, an asphalt overlay must have a balance of both good rut and crack resistance. Furthermore, overlay performance is highly influenced by many factors, such as existing pavement conditions, traffic loading, and environmental conditions. It has also recently become common practice to use two different materials in an overlay, the first being a crack resistant level up course and the second being a wearing surface. The properties of both overlay types have a big impact on performance.

The main objective of the Research Project 0-5123 was to develop a comprehensive mechanistic-empirical (ME) asphalt overlay design system to assist TxDOT engineers to make these design decisions. The design system developed incorporates models for both rutting and reflection cracking of the proposed overlay. The Paris' lawbased reflection cracking model was evaluated and recommended for use in this study. This model requires the use of both stress intensity factors (SIF) and fracture properties (A and n) for predicting crack propagation caused by both traffic loading and thermal effects. For practical implementation of the SIF concept, a total of 34 SIF regression equations were developed based on more than 1.6 million finite element computations. The required fracture properties can be easily determined using the Overlay Tester. The proposed reflective cracking model was calibrated using performance data from three HMA overlay field case studies and then verified using the California's Heavy Vehicle Simulator test results. To predict asphalt overlay rutting, the wellknown VESYS layer rutting model was used and later calibrated using the field rutting data from the National Center for Asphalt Technology (NCAT) test track 2006. The material properties required for this model are obtained from repeated load tests. The reasonableness and accuracy of the calibrated rutting was further verified by the field rutting data from NCAT test track 2000.

Finally, the calibrated reflective cracking and rutting models were integrated into an asphalt overlay thickness design and analysis program. To assist in implementation, default values of material properties have been provided for all the overlay types currently used in Texas. The program provides the designer with a tool to evaluate on a project-level basis the impact of load transfer efficiency (LTE) on predicted life and to determine what level of LTE must be repaired in order to achieve adequate performance. In summary this study has developed a comprehensive overlay thickness design and analysis system based on solid engineering principles.

The software package developed in this study has been provided to TxDOT. Based on the evaluations made in this study its predictions appear rational and reasonable. This system is ready for state-wide pilot implementation.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-5123-3.pdf

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Research Digest Item 11 Operating Guidelines for TxDot Ramp Control Signals TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 5294-P1 • 2009 The Texas Department of Transportation (TxDOT) currently maintains a Traffic Signals Manual. Originally published in 1999, this manual provides a guide and reference for handling requests for traffic signals on the designated State Highway System, including installations financed by federal funds and installed on the numbered State Highway System. It describes the steps necessary for installing a traffic signal, from project inception through construction and final disposition of records. It contains five chapters: Introduction, Requests for Traffic Signal, Traffic Studies, Operational considerations, and Traffic Signal Projects. It also contains two appendices: one that contains the forms necessary to warrant and install a traffic signal on TxDOT roadways and another for determining the need for traffic control at school crossings.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-5294-P1.pdf

Item 12 Evaluating and Improving Incident Management Using Historical Incident Data: Case Studies at Texas Transportation Management Centers TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 5485-1 • 2009 The companion guidebook (0-5485-P2) developed as part of this study provides the procedures and methodologies for effective use of historical incident data at Texas Transportation Management Centers (TMCs). This research report documents the results from the case studies conducted using the procedures outlined in the guidebook. Researchers examined the data collected from three Texas TMCs, which are Houston’s TranStar, Austin’s Combined Transportation and Emergency Communications Center (CTECC), and Fort Worth’s TransVISION. Researchers conducted six categories of analyses in this study – (a) analysis of incident characteristics, (b) hot spot analysis, (c) incident impact estimation, (d) analysis of incident management performance measures, (e) incident duration prediction, and (f) incident-induced congestion clearance time prediction.

Researchers found that historical incident data can be effectively used to support incident management and performance evaluation processes both reactively and proactively. Some procedures need to be automated to be used efficiently in day-to-day operations. As such, various prototype tools, such as the incident duration and incident-induced congestion clearance prediction tools, were developed during this study to facilitate and automate the proposed methodologies. These prototype tools provided a platform for TxDOT to deploy the research results in the future.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-5485-1.pdf

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Research Digest Item 13 Assessment of a Traffic Monitoring System for a Major Traffic Generator to Improve Regional Planning: Technical Report TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 5531-2 • 2009 The opening of a major traffic generator in the San Antonio area provided an opportunity to develop and implement an extensive traffic monitoring system to analyze local, area, and regional traffic impacts from the generator. Researchers reviewed the technical literature and the experiences of other areas with major traffic generators. Twenty-nine new traffic data collection sites were installed as part of the monitoring system, including two sites with new radar-based technology. This provided the Texas Department of Transportation with the opportunity to test new traffic data collection equipment . Researchers combined historical traffic data from the study area, travel time runs, commuter surveys, and data from new sites to measure impacts. The major generator created small impacts at or in the vicinity of its location in the study area. Changes recorded in the data from roadways farther out from the major generator were found not related to activities from the generator. The process of developing and implementing a monitoring system is transferable to other cities and regions and depends on available resources and agency interest.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-5531-2.pdf

Item 14 Delivery of Workshops on Mobility Monitoring in Small to Medium-Sized Communities TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 5571-01-1 • 2009 This report summarizes the delivery and outcome of a series of workshops conducted in 13 cities across the state on performing mobility monitoring in small to medium-sized communities. The workshops served as implementation for research project 0-5571, "Congestion Monitoring Measures and Procedures for Small to Medium-Sized Communities." This report summarizies the workshop locations and attendance, workshop agenda and materials, and workshop evaluations and participant feedback.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/5-5571-01-1.pdf

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Research Digest Item 15 Performance Evaluation of Cable Median Barrier Systems in Texas TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 5609-1 • 2009 Since 2003, the Texas Department of Transportation (TxDOT) has embarked on an aggressive campaign to install median barriers to prevent cross-median crashes on freeway facilities statewide. In the few years prior to 2003, virtually all fatalities on interstate facilities (96 percent) were the result of cross-median crashes. TxDOT used special safety funding to accelerate projects and decided to primarily implement high-tension cable/wire rope median barrier systems in lieu of concrete so that more roadway miles could be protected.

This report documents the performance evaluation of various cable barrier systems in Texas. The research evaluated TxDOT’s experience with cable barrier systems by analyzing installation cost, recurring maintenance costs and experiences, crash history before and after implementation, and field performance. Some of the key findings include: From a capital cost and life-cycle cost perspective, cable barrier is an attractive option compared to concrete median barrier. There has been a lack of coordination between TxDOT and emergency responders during the project planning and maintenance phases of cable barrier system projects. Maintenance costs and personnel requirements for cable barrier systems can be substantial and constrained maintenance budgets and personnel availability for frequent repair needs are issues. Cable barriers are performing extremely well and have had very few cases of penetration unless there were nonstandard impact conditions. Researchers believe that the cable barriers are functioning according to their intended design and are restraining vehicles that impact them in fashions similar to NCHRP 350 crash-testing guidelines. The installation of cable barriers has produced significant benefits with a reduction of 18 fatalities and 26 incapacitating injuries in the first full year. This reduction equates to an almost $46 million economic benefit based on current crash cost values used in evaluation of projects for safety funding. Due to problems experienced in Texas and other states, soil conditions should be considered as part of the project development process for cable barrier system installations.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-5609-1.pdf

Item 16 Potential Development of an Intercity Passenger Transit System in Texas-Report on Tasks 1-5 TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 5930-1 • 2009 This report summarizes the results of Tasks 1 through 5 of TxDOT Research Project 0-5930: Potential Development of an Intercity Passenger Transit System in Texas. Rather than focus on any regional commuter or light rail systems within or radiating from individual urban areas, this project aims to determine which longer intercity and interregional corridors are most likely to need additional intercity travel capacity in the coming decades. Using these tools, the state of Texas could determine in which corridors to most appropriately invest its resources to connect different regions of the state to create an interregional, statewide transit system.

The concept plan produced in Task 5 will be further explored in the remaining months of the project to determine potential costs and benefits of implementing the concept plan or individual components.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-5930-1.pdf _____________________________________________________________________________________________ Research and Technology Implementation Office February 2010 Page 10

Research Digest Item 17 Considerations for Rigid vs. Flexible Pavement Design when Allowed as Alternate Bids: Technical Report TEXAS A&M UNIVERSITY. TEXAS TRANSPORTATION INSTITUTE (TTI) TTI 6085-1 • 2009 This report documents the research conducted for the Texas Department of Transportation (TxDOT) concerning the use of pavement alternates. The scope of the project includes reviewing the state-of-the-practice in methods used for pavement type selection, interviewing TxDOT key personnel with experience in pavement design methods, developing guidelines with a protocol for considering rigid versus flexible pavement designs when allowed alternate bids, and developing the Alternate Pavement Design Analysis Tool (APDAT) for pavement type analysis.

Full-text PDF of this report is available for free download from http://tti.tamu.edu/documents/0-6085-1.pdf

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