Dedicated to providing knowledge, the Pavement Research Center uses innovative
research and sound engineering
principles to improve pavement structures, materials, and technologies.

NEWS (Previous News Items)

  • The UCPRC made podium and poster presentations at the 2016 Transportation Research Board (TRB) Annual Meeting held in Washington, DC on January 10-14, 2016. The presentations covered work sponsored primarily by the California Department of Transportation (Caltrans) as well as CalRecycle and the FHWA. Posted 2/8/2016.
  • The work being done by the UCPRC for Caltrans and others was presented at the Australian Asphalt Pavement Association Annual Conference from September 14-16, 2015. Presentations were made on CalME mechanistic-empricial design, development of mechanistic-empirical design methods, heavy duty asphalt pavement design, and a keynote address on driving innovation in pavements. Posted 10/19/2015.
  • A summary of the research findings and design procedure developed during the recently completed permeable interlocking concrete pavement study (see Summer 2015 UCPRC Activities below) was presented at the 11th International Conference on Concrete Block Pavement in Dresden, Germany in September. The design tables developed with the design procedure have been incorporated into the Interlocking Concrete Pavement Institute and ASTM guidelines for designing and constructing permeable interlocking concrete pavements. Posted 10/13/2015.
  • The Caltrans/UCPRC Heavy Vehicle Simulators have completed all testing of different full-depth pavement reclamation strategies on one of the instrumented test tracks at the UC Davis research facility. The strategies included pulverization with no stabilizer (FDR-NS), pulverization with cement (FDR-PC), pulverization with foamed asphalt/cement (FDR-FA), and pulverization with engineered emulsion (FDR-EE). Testing was done under both dry and soaked conditions, with a total of 8.5 million wheel load repetitions applied with the HVSs, equating to about 145 million equivalent single axle loads (ESALs) . A comprehensive forensic investigation has also been completed on each test section. Posted 10/13/2015.
  • The UCPRC has recently worked with colleagues in China and South Africa to expand knowledge of pavement life cycle assessment and support development of national programs for considering development and implementation of pavement LCA. A two day workshop (August 7-8) organized by Jia Yu of the Jiangsu Transportation Institute Group Company, Ltd. and Tan Yiqiu of the Harbin Institute of Technology, who also hosted the event, drew participants from across a wide range of stakeholders in China. Keynote presentations given by UCPRC are available here. In South Africa, the UCPRC participated in the 3rd ISAP International Symposium on Asphalt Pavements and the Environment which focused on improving the sustainability of pavements and was part of the 11th Conference on Asphalt Pavements in Southern Africa. The keynote presentation given by UCPRC on pavement LCA is available here. A workshop was held with industry, government and academic participants to discuss pavement LCA for application in southern Africa, and a resolution has been prepared from the workshop for review by government and industry in South Africa. Posted 8/25/2015.
  • A presentation by UCPRC researchers at the 52nd Petersen Asphalt Research Conference (July 13 to 15, 2015, in Laramie, Wyoming) described the progress of, and some recent findings from, three current studies: 1) Modification of the rolling thin-film oven (RTFO) test to simulate the realistic short-term aging of asphalt rubber binders (view presentation); 2) An evaluation of changes in the performance-related properties of conventional asphalt binder after it is blended with different amounts of age-hardened rubberized binder (view presentation); and 3) Development of a solvent-free approach for evaluating the properties of blended binders in mixes that have large reclaimed asphalt pavement (RAP) and reclaimed asphalt shingle (RAS) content (view presentation). Posted 8/7/2015.
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Spring 2016 UCPRC Activities


Candidate for fully permeable shoulder retrofit validation site

Brief Summary of Phase II Bike Study (SPE 4.57). The project was a continuation of a Phase I study that focused on bicycle club members and their bicycles and state highways, and also on recent changes in Caltrans’ chip seal specifications that resulted in larger stones in typically used seals. Phase I report has been published.

This Phase II project included other types of riders, bicycles and more local roads. The objective of this continued project (Phase II Bike Study for Local Streets) was to conduct the bike study on local streets and use Phase I and II results to prepare guidelines for design of preservation treatments suitable for bicycle routes on state highways and local streets in California.

In Phase II, macrotexture and roughness as well as distresses were measured for different preservation treatments on 67 road sections distributed across five cities (Davis, Richmond, Sacramento, Reno and Chico) in northern California and a number of Caltrans’ highway sections. Bicycle ride quality surveys were conducted and collected data from a total of 155 participants. Correlations of pavement texture, bicycle vibration and bicycle ride quality were developed. Correlations between pavement roughness and distresses, correlations of bike ride quality to roughness, and correlations between pavement texture and treatment specifications were preliminarily explored. Models for bicycle ride quality and physical rolling resistance were also developed. Long term monitoring of pavement macrotexture for larger stone seals on LA-2, SLO-1 and Mon-198 has also been completed to determine how much texture is reduced by traffic.

Major conclusions drawn from the results and analyses include:

  • Changes in Caltrans’ chip seal gradation specifications have resulted in higher macrotexture values, as seen on LA-2, SLO-1 and Mon-198, as examples.
  • From preliminary (Phase I on highways + Phase II on streets) results, 80% of riders rate pavements with Mean Profile Depth values 1.8 mm or less as acceptable; 50% rate MPD of 2.3 mm or less as acceptable.
  • Most slurries on city streets produce high acceptability across all cities.
  • A clear relationship was established between the critical aggregates sizes (#4 and #8) and MPD.
  • Pavement texture generally tends to decrease over time due to traffic, although not yet below the “acceptable” levels (according to survey) on the sections being surveyed.
  • Both IRI and MPD are important parameters to determine whether riders find a particular section acceptable.
  • There is considerable variability among people and among sections that influences acceptability.
  • The presence of distresses, particularly cracking, reduces the ratings given to pavement by bicycle riders.

Important Note for Caltrans Users: Prior to scheduling pavement preservation (preventive maintenance or CAPM) or roadway rehabilitation work on flexible pavement highway sections, the District Materials Engineer and/or the Project Manager should review this spreadsheet to ensure that the proposed project does not include sections active in the “Quieter Pavement Research” (QPR) testing program. If the proposed project is within a QPR test section, please contact Linus Motumah of the Caltrans Office of Pavement Design before scheduling the work.

To view maps that show where the sections are located, click the following link: (or copy-and-paste it into a new browser window for a slightly larger view).

For more information, contact John Harvey of the UCPRC or Linus Motumah.