The processes in the pavement life cycle can be defined as: material extraction and production; construction; transport of materials and demolition; the use stage, where the pavement interacts with other systems; the materials, construction, and transport associated with maintenance and rehabilitation; and end-of-life. Local governments are increasingly being asked to quantify greenhouse gas emissions from their operations and identify changes to reduce emissions. There are many possible strategies that local governments can choose to reduce their emissions, however, prioritization and selection of which to implement can be difficult if emissions cannot be quantified. Pavement life cycle assessment (LCA) can be used by local governments to achieve the same goals as state government. The web-based software environmental Life Cycle Assessment for Pavements, also known as eLCAP has been developed a project-level LCA tool. The goal of eLCAP is to permit local governments to perform project-level pavement LCA using California specific data, including consideration of their own designs, materials, and traffic. eLCAP allows modeling of materials, transport, construction, maintenance, rehabilitation, and end-of-life recycling for all impacts; and in the use stage it considers the effects of combustion of fuel in vehicles as well as the additional fuel consumed due to pavement-vehicle interaction (global warming potential only). This report documents eLCAP and a project that created an interface for eLCAP that is usable by local governments.
California’s truck fleet composition is shifting to include more natural gas vehicles (NGVs), electric vehicles (EVs), and fuel cell vehicles (FCVs), and it will shift more quickly to meet state greenhouse gas (GHG) emission goals. These alternative fuel trucks (AFTs) may introduce heavier axle loads, which may increase pavement damage and GHG emissions from work to maintain pavements. This project aimed to provide conceptual-level estimates of the effects of vehicle fleet changes on road and bridge infrastructure. Three AFT implementation scenarios were analyzed using typical Calif. state and local pavement structures, and a federal study’s results were used to assess the effects on bridges. This study found that more NGV, EV, and FC trucks are expected among short-haul and medium-duty vehicles than among long-haul vehicles, for which range issues arise with EVs and FCs. But the estimates predicted that by 2050, alternative fuels would power 25–70% of long-haul and 40–95% of short-haul and medium-duty trucks. AFT implementation is expected to be focused in the 11 counties with the greatest freight traffic—primarily urban counties along major freight corridors. Results from the implementation scenarios suggest that introducing heavier AFTs will only result in minimal additional pavement damage, with its extent dependent on the pavement structure and AFT implementation scenario. Although allowing weight increases of up to 2,000 lbs. is unlikely to cause major issues on more modern bridges, the effects of truck concentrations at those new limits on inadequate bridges needs more careful evaluation. The study’s most aggressive market penetration scenario yielded an approximate net reduction in annual well-to-wheel truck propulsion emissions of 1,200–2,700 kT per year of CO2 -e by 2030, and 6,300–34,000 kT by 2050 versus current truck technologies. Negligible effects on GHG emissions from pavement maintenance and rehabilitation resulted from AFT implementation.
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.
The University of California Pavement Research Center and the Interlocking Concrete Pavement Institute worked with partners in the concrete and asphalt pavement industries and Tongji University to organize a workshop in November 2017 with the goals of identifying knowledge, information, and communication barriers to adoption of permeable pavement of all types, and then creating a road map to address and overcome them. The workshop brought together stakeholders from the planning, stormwater quality, flood control, and pavement communities to listen to presentations, exchange ideas, discuss unanswered questions identified by the group, and develop a proposed road map to fill the gaps in knowledge, processes, and guidance. Participants represented local, state and federal government, consultants, non-governmental organizations, contractors/ material producers, and academia. The road map produced from the discussions is built around “routes” of proposed actions to remove technical and institutional barriers to realize the goal of making permeable pavements a fully viable alternative in standard practice.
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More than 90 percent of the road and highway network in the United States is paved with asphalt concrete. Maintenance and periodic rehabilitation require a continuous supply of aggregates and asphalt binder, both of which are becoming increasingly scarce and expensive. Recycling and reusing these resources can reduce costs and improve sustainability. The most common recyclable material used in road construction is reclaimed asphalt pavement (RAP), which is milled asphalt surface layers that have been removed from existing pavements before new asphalt overlay is placed. Reclaimed asphalt roofing shingles (RAS) are another potential source of asphalt binder.
There is growing interest in allowing significantly higher percentages of RAP and RAS in asphalt mixes used on state and local roadways. However, making this change has raised concerns regarding how these composite binders may influence the performance and durability of asphalt mixes, depending on the blends of different virgin and reused binders. Researchers at the UC Pavement Research Center investigated the use of higher percentages of RAP and RAS as a partial replacement for the virgin binder in new asphalt mixes and their effect on pavement performance in California. This research brief summarizes findings from that study.
In early 2017, the University of California Pavement Research Center (UCPRC) and the National Center for Sustainable Transportation (NCST), working with the Interlocking Concrete Pavement Institute (ICPI), identified gaps in knowledge and other barriers to wider implementation that were perceived to be holding back the full potential for deployment of pavements that can simultaneously solve transportation, stormwater quality, and flood control problems. Further discussions were held with the National Ready Mixed Concrete Association (NRMCA), the National Asphalt Pavement Association (NAPA), and the Tongji University Sponge City Project (Shanghai, China). A workshop was organized in November 2017 based on those discussions with the goal of identifying knowledge, information, and communication barriers to adoption of permeable pavement of all types, and creation of a road map to address and overcome them. The workshop brought together a diverse group of stakeholders from the planning, stormwater quality, flood control, and pavement communities to hear listen to presentations, exchange and discuss unanswered questions identified by the group, and then to discuss a proposed road map to fill the gaps in knowledge, processes, and guidance. This document is the result of that workshop and additional development of the road map. It presents the organization of the workshop, summaries of the presentations and the breakout and plenary discussions, and the final road map developed from the results of the workshop.
This report presents the implementation of new design method developed using mechanistic-empirical design approach by University of California Pavement Research Center (UCPRC) through building two test sections at California State University Long Beach (CSULB). The study includes a literature review, pavement design procedure, mix design, construction procedure, instrumentation, and collection of performance data of the permeable asphalt and concrete pavement sections for validation and structural design calibration of the new design approach. Fully permeable pavements are characterized as those in which all layers are porous, and the pavement structure serves as a reservoir to store water and minimize the negative impacts of stormwater spillover. The California Department of Transportation (Caltrans) has shown interest in developing fully permeable pavement design for use in territories that convey substantial truck activity as a potential stormwater management best management practice (BMP) to give low-effect infrastructure and proficient framework operation. A location was selected within CSULB for the construction of the test sections. Pressure cells and strain gages were installed during the construction of pavements for measuring the stress on the top of subgrade on both test sections and the strain at the bottom of surface layer to assess the performance of the fully permeable pavements. In the study, the traffic count was also determined. The data acquisition device CDaq was installed at the site to collect the data. The recorded data was analyzed using the MATLAB program code. The data from pressure cells and strain gages are analyzed, and graphs were plotted to study the pattern in the data sets. The stress and strain measurements and the cracking (both sections) and rutting (asphalt section only) will be used to calibrate the pavement structural design procedure and hydraulic performance will also be monitored.
This white paper presents the results of a survey administered by the University of California Pavement Research Center (UCPRC) exploring the successes, challenges, funding, and organizational structure of six centers in other states that share a similar mission to support the improvement of city and county pavement practices. Five of the six centers that participated in the survey are statewide centers located in Iowa, Minnesota, North Dakota, Ohio and Texas. The sixth is a regional center located in Washoe County, Nevada, the Regional Transportation Commission. These centers were selected as being the nation’s most advanced based on an extensive internet search and discussions with key pavement professionals across the country.
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