Tag Archives: Research

Tools for Planning and Monitoring Research Projects

Schematic for project planning

Schematic for project planning

The UDOT Research Division recently updated their Project Management Checklist. The checklist is a tool for use in planning and monitoring progress of new research projects at UDOT. It is available on the Research Division website under Project Tool Box, along with a new Project Management Worksheet which helps to define the project prior to contracting with a university or consultant.

A previous version of the checklist had been in use for several months and was based on project management training given to UDOT regional and central project managers by Ernie Nielsen of BYU. In early 2014 the Research Division staff received additional training from Ernie Nielsen in using the project planning principles within the checklist, including an exercise using an actual new research project. Based on that exercise the checklist was refined and the worksheet was created in July 2014.

Project management worksheet excerpt

Project management worksheet excerpt

The updated checklist is a simplified version of the previous one and is well suited for the typical size of research projects funded at UDOT. The new worksheet helps key individuals inside and outside UDOT, representing groups most affected by and most able to contribute to the research, to define the project objective and deliverables. These tools help research project managers involve the right people in planning and conducting the research, preparing the way for effective implementation of research results at UDOT.

Research projects at UDOT typically have much smaller budgets, have fewer activities or tasks, and are more focused on incremental process improvements than regular UDOT projects. UDOT research projects are usually completed within one or two years, and the majority of these come from the annual Research Workshop where submitted problem statements are prioritized. Both types of projects can benefit from the same project management principles, including effective planning and scheduling of tasks and resources. Scheduling tools used on UDOT research projects vary from basic MS Project files to spreadsheets to track tasks and milestones.

We look forward to working with our research project champions, technical advisory committees, and researchers while benefiting together from using these new tools.

This guest post was written by Davis Stevens, P.E., UDOT Research Project Manager and was originally published in the Fall 2014 Research Newsletter.

Comparison of Wintertime Asphalt and Concrete Pavement Surface Temperatures in Utah

Because winter maintenance is so costly, UDOT personnel asked researchers at Brigham Young University (BYU) to determine whether asphalt or concrete pavements require more winter maintenance. Differing thermal properties suggest that, for the same environmental conditions, asphalt and concrete pavements will have different temperature profiles. Climatological data from 22 environmental sensor stations (ESSs) near asphalt roads and nine ESSs near concrete roads were used to determine which pavement type has higher surface temperatures in winter.

Twelve continuous months of climatological data were acquired from the road weather information system operated by UDOT, and erroneous data were removed from the data set. In order to focus on the cold-weather pavement surface temperatures, a winter season was defined as the period from November through April, and the data were divided into time periods that were based on sunrise and sunset times to match the solar cycle.

To predict pavement surface temperature, a multiple linear regression was performed with input parameters of pavement type, time period, and air temperature. As shown in Table 1, the statistical analysis predicting pavement surface temperatures showed that, for near-freezing conditions, asphalt is better in the afternoon, and concrete is better for other times of the day. However, neither pavement type is better, on average, across the locations studied in this research. That is, asphalt and concrete are equally likely to collect snow or ice on their surfaces, and both pavements are expected to require equal amounts of winter maintenance, on average.

To supplement these analyses, which provided useful information about average pavement temperatures across the statewide pavement network, additional analyses of asphalt and concrete pavement surface temperatures were performed for a particular location in a mountainous region of northern Utah more typical of canyon areas. Asphalt and concrete pavement surface temperatures were directly compared at a location on U.S. Route 40 near Heber where asphalt and concrete meet end to end at the base of a mountain pass. As shown in Figure 1, an ESS was installed to facilitate monitoring of asphalt and concrete pavement surface temperatures, as well as selected climatic variables, at the site.

Data collected during the three winter seasons from 2009 to 2012 were analyzed in this research, and the same months and time periods used in the previous study were applied in this analysis as well. To compare the surface temperatures of the concrete and asphalt pavements during freezing conditions, multivariate regression analyses were performed. Equations were generated for three response variables, including the asphalt surface temperature, concrete surface temperature, and difference in temperatures between the asphalt and concrete surfaces.

The statistical models developed in the analyses show that the surface temperature of both asphalt and concrete pavement increases with increasing air temperature and decreases with increasing relative humidity and wind speed, and that the difference in pavement temperatures decreases with decreasing air temperature. For the studied site, the data indicate that concrete pavement will experience freezing before asphalt pavement for all time periods except late afternoon, when the pavement types are predicted to freeze at the same air temperature (see Table 2). Therefore, for material properties and environmental conditions similar to those evaluated at this U.S. 40 site, asphalt would require less winter maintenance, on average, than concrete.

Due to the interactions among albedo, specific heat, and thermal conductivity, the actual thermal behavior of a given pavement will depend on the material properties and environmental conditions specific to the site. As shown in this research, concrete pavement can be warmer than asphalt, which is typical of the statewide pavement network, on average, during late morning, evening, night, and early morning. However, the research also clearly shows that, in mountainous regions of northern Utah more typical of canyon areas, engineers may expect asphalt pavement to be warmer than concrete, or equal in temperature to it, during all time periods at sites that receive direct sun exposure, such as the one on U.S. Route 40 that was studied in this research. At such sites, selection of asphalt pavement may facilitate reduced winter maintenance costs; however, though statistically significant, relatively small differences in temperature between asphalt and concrete pavement surfaces may not warrant differences in actual winter maintenance practices. Other factors beyond pavement type, such as rutting and surface texture, may more strongly affect winter maintenance and should also be considered.

The results of the statewide comparison of wintertime temperatures of asphalt and concrete pavements, as well as the specific results for the U.S. 40 site near Heber, are detailed in two separate research reports available on the Research Division website.

This guest post was written by W. Spencer Guthrie, Ph.D., M.ASCE, Brigham Young University, and David Stevens, P.E., Research Program Manager, and was originally published in the Research Newsletter.

Grouted Splice Sleeve Connectors for ABC Bridge Joints in High-Seismic Regions

Photos and diagram of different kinds of GSS connectors

Figure 1. Two types of GSS connectors used: (a) FGSS, (b) GGSS, (c) FGSS-1, (d) GGSS-1

In recent years, the Accelerated Bridge Construction (ABC) method has received attention in regions of moderate-to-high seismicity. Prefabrication of bridge structural components is a highly effective method in this process and one of the ABC methods for Prefabricated Bridge Elements and Systems (PBES) advanced by the Federal Highway Administration. Joints between such precast concrete components play an important role in the overall seismic performance of bridges constructed with the ABC method. Research has been carried out at the University of Utah to investigate potential ABC joint details for bridges located in high-seismic regions. A connector type, referred to as a Grouted Splice Sleeve (GSS), is studied for column-to-footing and column-to-cap beam joints. Two GSS connectors commonly used in buildings were utilized in this study, as shown in Fig. 1. The column-to-cap beam joints used a GSS connector where one bar was threaded into one end and the other bar was grouted into the opposite end (denoted as FGSS), as shown in Fig. 1(a) and Fig. 1(c). The column-to-footing joints incorporated another type of GSS where the bars were grouted at both ends (denoted as GGSS), as shown in Fig. 1(b) and Fig. 1(d).

Drawings of the test specimen alternatives

Figure 2. Configuration of test specimen alternatives

Three precast alternatives in addition to one conventional cast-in-place half-scale model were constructed for each category, as shown in Fig. 2; the column-to-cap beam joints were tested upside down. The GSS connectors were placed in the column base (GGSS-1) or column top (FGSS-1) in the first alternative. The location of the GSS connectors changed to the top of the footing (GGSS-2) and bottom of the cap beam (FGSS-2) to study the performance of the joints when the GSS connectors were outside the plastic hinge zone of the column in the second alternative. The dowel bars in the footing and the cap beam were debonded over a length equal to eight times the rebar diameter (8db) for the third alternative in both categories, while the GSS connectors were embedded in the column base (GGSS-3) or column top (FGSS-3). The last specimen type was the cast-in-place joint, in which continuous bars from the footing and cap beam were used to build the columns with-out bar splices (GGSS-CIP and FGSS-CIP).

Photos of the speciment

Figure 3. Specimen GGSS-3 at a drift ration of 7%: (a) overall view; (b) footing dowel at joint interface

Experimental results under cyclic quasi-static loading showed that the performance of all joints was satisfactory in terms of strength and stiffness characteristics. However, the hysteretic performance and displacement ductility capacity of the specimens were distinct. Improved seismic response was observed when the GSS connectors were located inside the footing (GGSS-2) and the cap beam (FGSS-2) rather than the corresponding column end. The debonded rebar zone enhanced the ductility level and the hysteretic performance of the joints. This technique was found to be highly effective for the column-to-footing joint (GGSS-3), as shown in Fig. 3. As expected, the cast-in-place joints performed the best.

Even though AASHTO Specifications currently do not allow the use of connectors in the plastic hinge region, all joints tested in this research demonstrated acceptable ductility for moderate-seismic regions and some joints demonstrated acceptable ductility for high-seismic regions. The GSS connectors studied in this research were promising, especially when considering the time-saving potential of joints constructed using ABC methods; however, the different hysteretic performance and reduced displacement ductility of various alternatives com-pared to the cast-in-place joints must be accounted for in design.

Acknowledgments: This study is described further, including recent reports, on the TPF-5(257) website. The authors acknowledge the financial support of the Utah, New York State and Texas Departments of Transportation, and the Mountain Plains Consortium. The authors also acknowledge the assistance of Joel Parks, Dylan Brown, and Mark Bryant of the University of Utah.

This guest post was written by Chris P. Pantelides, Ph.D., University of Utah, M.J. Ameli, University of Utah, and Jason Richins, S.E., Research Engineering Manager and was originally published in the Research Newsletter

400 South Corridor Assessment

LRT Study

Figure 1. Roadway and LRT Study Network

This study evaluated current and future traffic and transit performance along the light rail transit (LRT) corridors within the University of Utah area, 400 South and Downtown Salt Lake City before and after an introduction of an additional LRT line. The analysis of different scenarios and on different network levels was performed using VISSIM microsimulation coupled with Siemens Next-Phase Software-in-the-Loop traffic controllers. The scenarios were evaluated for three different target years: 2013/2014, 2020 and 2025. Additional scenarios included alternative intersection configuration, with modified left turn operations at intersections of 400 South and Main, 400 South and State, and 400 South and 700 East.

Screenshot of the intersection simulation

Figure 2. Main Street and 400 South Intersection in Simulation

The analysis showed that the additional LRT line did not have significant impacts on traffic and transit operations. The highest impacts were experienced at intersections close to the Downtown area, mainly 400 South and State Street, and 400 South and Main Street, and North Temple and 400 West. The study also recommended potential signal improvements at these locations consisting of re-phasing, re-timing and modifying LRT preemption. The analysis also showed that it might be beneficial removing the shared lane sites at intersections along 400 South, since close to 70% of drivers are using the non-shared left turn lane, resulting in sub-optimal intersection operations.

This study was coordinated between UDOT, Utah Transit Authority, and other agencies.

This guest post was written by Milan Zlatkovic, University of Utah, Ivana Tasic, University of Utah, Marija Ostojic, Florida Atlantic University, and Aleksander Stevanovic, Florida Atlantic University, and was originally published in the Research Newsletter.

Pooled Fund: Performance-Based Assessment of Liquefaction

A new study led by UDOT and funded through the FHWA Transportation Pooled Fund Program began in March and is progressing well. The study is number TPF-5(296), entitled “Simplified SPT Performance-Based Assessment of Liquefaction and Effects.” A research team from Brigham Young University (BYU) is performing the two-year study. Other state DOTs participating in the study include Alaska, Connecticut, Idaho, Montana, and South Carolina.

Liquefaction of loose, saturated sands results in significant damage to buildings, transportation systems, and lifelines in most large earthquake events. Liquefaction and the resulting loss of soil shear strength can lead to lateral spreading and seismic slope displacements, which often impact bridge abutments and wharfs, damaging these critical transportation links at a time when they are most needed for rescue efforts and post-earthquake recovery.

Most commonly used liquefaction and ground deformation evaluation methods are based on the concept of deterministic hazard evaluation, which is related to the maximum possible earthquake from nearby faults. Recent advances in performance-based geotechnical earthquake engineering have introduced probabilistic uniform hazard-based procedures for evaluating seismic ground deformations within a performance-based framework, from which the likelihood of exceeding various magnitudes of deformation within a given time frame can be computed. However, applying these complex performance-based procedures on everyday projects is generally beyond the capabilities of most practicing engineers.

The objective of the new study is to create and evaluate simplified performance-based design procedures for the a priori prediction of liquefaction triggering, lateral spread displacement, seismic slope displacement, and post-liquefaction free-field settlement using the standard penetration test (SPT) resistance. Many of the analysis methods used to assess liquefaction hazards are based on SPT resistance values since the SPT is commonly used in site soil characterization for building, transportation, and lifeline projects.

This study represents a worthwhile pilot study which could prepare the way for additional research with the U.S. Geological Survey to further the use of the simplified, performance-based method.

Figure 1: Liquefaction loading map (return period = 1,033 years) showing con-tours of CSRref (%) for a portion of Salt Lake Valley, Utah

Figure 1: Liquefaction loading map (return period = 1,033 years) showing con-tours of CSRref (%) for a portion of Salt Lake Valley, Utah

The key to the simplified method is the use of a reference soil profile in development of liquefaction loading maps which are then used with the site’s soil data to estimate effects of liquefaction. An example map is shown in Figure 1, where CSRref represents a uniform hazard estimate of the seismic loading that must be over-come to prevent liquefaction triggering, if the reference soil profile existed at the site of interest.

Derivations for simplified performance-based liquefaction triggering and lateral spread displacement models have been completed in the study. Validation efforts have shown that the simplified results approximate the full performance-based results within 5% for most sites that were evaluated.

A summary of the study work plan and copies of current reports from the study are available at the TPF-5(296) study website.

This guest post was written by Kevin Franke, Ph.D., P.E., from BYU, and David Stevens, P.E., Research Program Manager, and was originally published in the Research Newsletter.

Results of the 2014 Research Workshop (UTRAC)

Photo of session attendees listening to speaker

Traffic Management & Safety breakout session

Projects have been selected for FY15 funding from the 2014 UDOT Research Workshop held on April 30th.

Fifty-nine problem statements were submitted this year for the UDOT Research Workshop. Of these, 16 will be funded as new research projects through the Research Division. Some submitted problem statements will be funded directly by other divisions.

The workshop serves as one step in the research project selection process which involves UDOT, FHWA, universities, and others. UDOT Research Division solicited problem statements for six subject areas: Materials & Pavements, Maintenance, Traffic Management & Safety, Structures & Geotechnical, Preconstruction, and Planning.

At the workshop, transportation professionals met to prioritize problem statements in order to select the ones most suitable to become research projects.

After the workshop, UDOT Research Division staff reviewed prioritization and funding for each recommended problem statement with division and group leaders and presented the list of new projects to the UTRAC Council.

The selected new projects include:

  • Asphalt Mix Fatigue Testing using the Asphalt Mix Performance Tester (CMETG)
  • Developing a Low Shrinkage, High Creep Concrete for Infrastructure Repair (USU)
  • Prevention of Low Temperature Cracking of Pavements (U of U)
  • Review and Specification for Shrinkage Cracks of Bridge Decks (U of U)
  • Incorporating Maintenance Costs and Considerations into Highway Design Decisions (U of U)
  • Unconventional Application of Snow Fence (UDOT)
  • Statistical Analysis and Sampling Standards for MMQA (U of U)
  • National Best Practices in Safety (UDOT)
  • I-15 HOT Lane Study – Phase II (BYU)
  • Characteristics of High Risk Intersections for Pedestrians and Cyclists-Part 3 (Active Planning)
  • Safety Effects of Protected and Protected/Permitted
  • Left-Turn Phases (U of U)
  • Development of a Concrete Bridge Deck Preservation Guide (BYU)
  • TPF-5(272) Evaluation of Lateral Pile Resistance Near MSE Walls at a Dedicated Wall Site (BYU)
  • Active Transportation – Bicycle Corridors vs. Vehicle Lanes (BYU)
  • Investigating the Potential Revenue Impacts from High-Efficiency Vehicles in Utah (UDOT)
  • Developing a Rubric and Best Practices for Conducting Bicycle Counts (Active Planning)

At the April 30th workshop, Dr. Michael Darter of Applied Research Associates gave an inspiring keynote ad-dress on collaboration between state DOTs and academia in developing innovative ideas. Also at the workshop, Barry Sharp, recently retired from UDOT, was presented with the UTRAC Trailblazer Award for his significant contributions towards improving UDOT research processes and the use of innovative products in transportation. Russ Scovil was our workshop coordinator and did a great job.

We appreciate everyone’s participation in the work-shop process. The new research projects can start as early as July 2014 in coordination with UDOT Research staff and champions.

To see details on the new projects and all submitted problem statements, visit the UDOT Research Division website.

This guest post was written David Stevens, P.E., Research Project Manager, and was originally published in the Research Newsletter.