Dedicated to providing knowledge, the University of California Pavement Research Center uses innovative research and sound engineering principles to improve pavement structures, materials, and technologies.
Guidelines for the Selection, Specification, and Application of Chemical Dust Control and Stabilization Treatments on Unpaved Roads
Unacceptable levels of dust, poor riding quality, impassability in wet weather, and unsustainable maintenance and gravel replacement practices are experienced on most unpaved road networks, and although it is acknowledged that unpaved roads are fundamental to local, regional, and national economies, many current management practices used on these roads leave much to be desired. Over the past 100 years a range of chemical treatments has been developed to fill the need for reducing the environmental and social impacts of road dust, improving the performance and safety of unpaved roads, and/or improving the properties of marginal materials to the extent that a road can be given all-weather status or upgraded to a paved standard. Most of these chemical treatments are proprietary and there is often little documented information regarding the chemistry of the treatment, the results of experimental trials to determine under what conditions the chemical treatment will work best, or guidelines on where and how to use the treatment. Most unpaved road chemical treatments carry no formal specification nor do they adhere to formal environmental testing requirements. Consequently, there has been no large-scale effort to establish and/or implement formal unpaved road chemical treatment programs anywhere in the world, other than those used in site-specific industrial applications such as mining operations. This guide introduces a new process for selecting an appropriate chemical treatment category for a specific set of unpaved road conditions using ranked potential performance. The process is based on the practitioner setting an objective for initiating a chemical treatment program and understanding the road in terms of materials, traffic, climate, and geometry. Using the information collected, the most appropriate chemical treatment subcategories for a given situation can be selected from a series of charts and ranked using a simple equation. This process can be completed manually using a paper form, or by using a web-based (www.ucprc.ucdavis.edu) or spreadsheet tool. Matrices for each of the objectives were developed based on documented field experiments and the experience of a panel of practitioners. Guidance on specification language for procuring and applying unpaved road chemical treatments is also provided, along with comprehensive guidance on understanding unpaved road wearing course material performance.
This document provides guidelines for the establishment, monitoring and reporting of pavement preservation experiments in California. Information is provided in chapters covering: Management and responsibilities, Project fundamentals, Experiment work plan, Site selection, Experiment construction, Experiment monitoring, Forensic investigations, Laboratory testing, Data analysis, reports and implementation, Data management and documentation, Example experiment work plans, checklists and form. The document aims to assist with achieving successful completion of experiments and implementation of the findings.
This document provides guidelines for the establishment, monitoring and reporting of pavement preservation experiments in California. Information is provided in chapters covering: Management and responsibilities, Project fundamentals, Experiment work plan, Site selection, Experiment construction, Experiment monitoring, Forensic investigations, Laboratory testing, Data analysis, reports and implementation, Data management and documentation, Example experiment work plans, checklists and forms The document aims to assist with achieving successful completion of experiments and implementation of the findings.
Medium- and heavy-duty trucks on California’s roads are shifting from conventional gasoline and diesel propulsion systems to alternative fuel (natural gas, electric, and fuel cell) propulsion technologies, spurred by the state’s greenhouse gas (GHG) reduction goals. While these alternative fuel trucks produce fewer emissions, they are also currently heavier than their conventional counterparts. Heavier loads can cause more damage to pavements and bridges, triggering concerns that clean truck technologies could actually increase GHG emissions by necessitating either construction of stronger pavements or more maintenance to keep pavements functional. California Assembly Bill 2061 (2018) allows a 2,000-pound gross vehicle weight limit increase for near-zero-emission vehicles and zero-emission vehicles to enable these trucks to carry the same loads as their conventional counterparts. The law also asked the UC Institute of Transportation Studies to evaluate the new law’s implications for GHG emissions and transportation infrastructure damage. To conduct this analysis, researchers at UC Davis considered three adoption scenarios of alternative fuel trucks in two timeframes, 2030 and 2050 (Figure 1). Based on these scenarios, the researchers used life cycle assessment and life cycle cost analysis to evaluate how heavier trucks might affect pavement and bridge deterioration, GHG emissions, and state and local government pavement costs. The study did not evaluate the safety implications of increasing allowable gross vehicle weights.
This document constitutes the user manual for tBeam, standalone software for the analysis of energy dissipation in pavements under moving vehicles. tBeam was developed as part of the improvement of modeling capabilities for environmental life cycle assessment of pavements being conducted by the University of California Pavement Research Center for the California Department of Transportation. tBeam is finite element based, employing multi-layered three-node Timoshenko beam elements resting on a viscoelastic Winkler foundation. It provides an approximation of the deflection bowl of pavements and the energy dissipated in pavement structures when subjected to loads moving at constant velocities. tBeam supports two loading options: a uniform pressure (per unit length) applied to a segment at the center of the beam, and a rolling rigid wheel. To achieve numerical efficiency the load-beam-foundation system is represented relative to a moving coordinate system attached to the moving load. The higher efficiency is made possible because, in this framework, an observer attached to the moving coordinate system perceives a “static” state (i.e., independent of time). The standalone tBeam software serves two purposes. First, to provide developers of pavement LCA tools a “guide” as to how to integrate tBeam technology into their program. To this end, the “main” of tBeam can be used as “guide” for integrating tBeam capabilities within the LCA tool. Second, tBeam capabilities are relevant to pavement research in general. Thus, it could represent a useful addition to the toolset for pavement viscoelastic mechanics.
The work described in this report is adjunct to a five-year study of tire/pavement noise undertaken by the University of California Pavement Research Center for the California Department of Transportation under the Partnered Pavement Research Center program (PPRC). This part of the study was performed in cooperation with the Danish Road Institute/Road Directorate, and it examined the influence of air temperature on tire/pavement noise measurements performed on two types of tires (Aquatred and Standard Reference Test Tire [SRTT]) on different asphalt pavement surfaces using the On-board Sound Intensity (OBSI) method. Field noise measurement testing was carried out in two series: one in the Southern California desert on State Route 138 using the SRTT, and the other with data collected on a statewide selection of pavements tested with the Goodyear Aquatred tire in an earlier part of the PPRC noise study. The field measurements yielded data for deriving air temperature coefficients for the two types of tires, and a comparison of them is made. A worldwide survey of the available literature accompanies the field work and analysis, and a summary of it is used to compare the air temperature coefficients of the SRTT with a combination of tire types used in European testing. In addition, findings in the literature serve as the basis for a series of predicted temperature coefficients for passenger cars on various cement concrete and asphalt pavements. Finally, the report presents ten general conclusions drawn regarding the relationship between air temperature correction and tire/road noise on asphalt and concrete pavements.
This report presents a series of methods implemented in Denmark and other European countries for the assessment and control of the impacts of highway noise on the neighboring public. It introduces Danish guidelines for the assessment of noise impact. Also described are examples of noise abatement planning for three different cases: planning of new highways, planning of highway widening projects, and noise abatement on existing highways. Experience shows that there is no single approach that can remove all noise problems along highways. It will be necessary for more effective noise abatement to take different approaches together, including noise-reducing pavements, noise barriers, facade insulation, and proper land use strategies. Harmonized public-private partnership is also critical for successful implementation of public policy and regulations related to noise abatement.
Development of an Empirical-Mechanistic Model of Overlay Crack Progression using Data from the Washington State PMS Database
This is the second of two reports that present fatigue cracking performance models for asphalt concrete overlays placed on existing asphalt concrete pavement. The models were developed from the pavement management system (PMS) database of the Washington State Department of Transportation (WSDOT). The database included existing pavement structure, overlay thickness and type, truck traffic, and observed percent of the wheelpath cracked from annual condition surveys. Climate data was developed by the UCPRC to augment the WSDOT data. This report presents a model for crack propagation, starting from crack initiation, which was defined as 5 percent of the wheelpath with longitudinal cracking. The combined initiation and propagation models were included in a spreadsheet calculator which was used to perform an analysis of the sensitivity of crack initiation and propagation to the input variables. The models are extremely useful for predicting pavement performance. For use in California they will need recalibration of the coefficients to reflect differences in WSDOT and California practice, primarily the use of thicker overlays in California, placement of overlays at much more advanced states of cracking in the existing pavement, and possible differences in routine maintenance activities.
CAL/APT Program: Test Results from Accelerated Pavement Test on Pavement Structure Containing Asphalt Treated Permeable Base (ATPB) Section 500RF
This report is the second in a series which describe the results of tests on full-scale pavements constructed at the Richmond Field Station (RFS) which have been designed and constructed according to Caltrans procedures. It contains a summary of the results and their interpretation of the Heavy Vehicle Simulator (HVS) tests on the first of four pavement test sections, an asphalt-concrete section containing an asphalt-treated permeable base (ATPB), designated section 500RF. The tests on the four test sections have been performed as part of Goal 1 of the CAL/APT Strategic Plan (1). One objective of the test program [described in Reference (2)] is to develop data to quantitatively verify existing Caltrans pavement design methodologies for Asphalt Treated Permeable Base (ATPB) pavements and conventional Aggregate Base (AB) pavements with regard to failure under trafficking at moderate temperatures (Goal 1), while preparing a uniform platform on which overlays (Goal 3 of the Strategic Plan) will be constructed which also will be trafficked. The objective of the program includes: quantification of the effective elastic moduli of the various pavement layers, based on an ad-hoc use of layered elastic analysis; quantification of the stress dependence of the pavement layers; determination of the failure mechanisms of the various layers; and determination and comparison of the fatigue lives of the two types of pavement structure.
Mechanistic-Empirical (ME) Design: Mix Design Guidance for Use with Asphalt Concrete Performance-Related Specifications
Caltrans has adopted mechanistic-empirical (ME) methods for flexible pavement design, and is using performance-related construction specifications on some projects for hot mix asphalt. Performance-related specifications are used to help ensure that as-built materials meet the performance requirements assumed in ME pavement structural designs. PRS pose new challenges for materials producers and contractors who have never had to relate volumetric mix design parameters to achievement of mechanistic parameters for fatigue life and rutting resistance based on results from performance-related laboratory tests. The objective of this project is to provide guidance to mix designers and contractors to support their decision making regarding changes to mix designs to achieve PRS requirements. The guidance presented in this report was initially developed based on past experience. To validate the guidance and demonstrate its usage, a production mix approved by the California Department of Transportation was selected as the starting point for a set of adjustments applied to the mix and measurement of the effects of each adjustment on mechanistic performance indicators. A total of three sets of adjustments were evaluated, which resulted in a total of four mixes including the baseline. The mechanistic performance parameters evaluated in this study include stiffness, fatigue resistance, and rutting resistance. In addition to direct comparison of laboratory test results, mechanistic-empirical simulations were conducted to evaluate the laboratory mix performance results on predicted pavement performance when the mix was used as a pavement surface layer. The initial mix design guidance was found to be generally consistent with the laboratory test results for the example mix albeit with some minor exceptions. The mix design guidance was then revised based on findings from this study. It is recommended that the revised guidance be used and more data collected to make further improvements.
White Paper on Alternate Strategies for Reducing Greenhouse Gas Emissions: A Life Cycle Approach Using a Supply Curve
The purpose of this white paper is to provide Caltrans with a methodology that uses LCA and LCCA analyses to create a “supply curve” that ranks the different strategies/actions that can be taken to reduce GHG emissions and lessen any other environmental impacts that affect ecosystems and human health. For Caltrans to implement the proposed methodology, the process must be validated and assessed using currently available actions. This white paper presents the methodology and demonstrates its initial use in quantifying and ranking several potential strategies.
Related Research Centers & Groups
- 3 Revolutions Future Mobility Program
- China Center for Energy and Transportation
- Energy Futures Research Center
- Hydrogen Pathways Program
- National Center for Sustainable Transportation
- Plug-In Hybrid & Electric Vehicle Research Center
- Sustainable Freight Research Center
- Sustainable Transportation Center
- Sustainable Transportation Energy Pathways (STEPS)
- Urban Land Use and Transportation Center
- Policy Institute for Energy, Environment, and the Economy
- UC Davis Institute of Transportation Studies