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Current Caltrans Standard Specifications for rubberized hot mix asphalt–gap-graded (RHMA-G) do not allow the inclusion of reclaimed asphalt pavement (RAP). This report summarizes the research conducted by the UCPRC in support of the Caltrans-industry initiative “10% RAP in RHMA-G,” whose goal is to evaluate the use of up to 10% RAP (by aggregate replacement) in RHMA-G mixes, provided that the research does not identify significant potential problems for durability. Five pilot projects were built by Caltrans as part the initiative. In each of the pilots, a control RHMA-G (without RAP) and an RHMA-G with 10% RAP were placed. The mixes were sampled during production and tested using performance-related tests at the UCPRC laboratory. The results of the testing of the mixes—including stiffness, four-point bending fatigue resistance, and rutting resistance—indicate that the addition of 10% RAP had minor effects on the mechanical properties of the RHMA-G. With just a few exceptions related to changes in the total binder content of the mix, the effect of the RAP addition was negligible compared with project-to-project differences. Modeling with CalME software based on four-point bending testing results indicated that the impact of the RAP addition on the cracking performance of the pavement was either negligible or comparable to project-to-project differences. From the constructability point of view, the addition of the RAP did not create any problems. The life cycle assessment presented in this report indicates that the addition of 10% RAP to the RHMA-G can reduce the greenhouse gasses emissions associated with the RHMA-G production (cradle-to-gate) by up to 5%.

This report is a comprehensive review of natural and human-made materials with the potential to reduce cement content in concrete by partially replacing portland cement or as additives. The review aims to reveal possible source materials as alternative supplementary cementitious materials (ASCMs) to coal-burned fly ash and ground granulated blast furnace slag as these SCMs supplies rapidly decline. Information required to estimate supplies of each ASCM was gathered, and ASCM candidates with enough abundance to support California’s concrete paving sector were identified for further laboratory evaluation. In addition, the required chemical, thermal, and mechanical treatments of the source materials were gathered so the environmental and economic impacts of the processes could be considered. A review of scientific literature on the technical performance of the studied materials in cement paste, mortar, or concrete was also conducted when that information was available.The reviewed feedstock material categories include biomass sources, construction and demolition wastes, natural pozzolans (volcanic and sedimentary materials), and post-consumer waste. As part of the biomass category, biopolymer-based nanomaterials were also included in the review for their promise to reduce cement content from added strength. The following information was included for each material considered in this report: feedstock description, the potential mechanism of performance in concrete, physical and chemical properties, feedstock supplies and processing method, technology readiness level (TRL), a summary of technical performance in cementitious systems based on the scientific literature, environmental impacts of the production phase, and cost considerations.Based on the comprehensive information gathered, several materials present potential as ASCMs, fillers, and admixtures for the California paving industry. However, most materials identified are at TRL 3 or 4, requiring more research and development to move toward implementation. In addition, some of these ASCMs may not fully satisfy the current regulations for SCMs. For example, biomass ash from some sources may contain a high alkaline content and a greater than 6% unburnt carbon content. Furthermore, some natural pozzolans impose a high water demand and have slow strength gain. In addition, the reported performance in the literature for the biobased nanomaterials studied is conflicting and performance data in concrete is scarce. Finally, some reviewed materials were not selected for more advanced laboratory evaluation because a supplier was not found in California. These materials include municipal solid waste ash, wastewater treatment sludge, and seashell waste. In addition, ground glass, harvested coal-burnt fly ash, and fines from carpet recycling were not chosen for laboratory evaluation because they are being investigated in other Caltrans and non-Caltrans research contracts.

In this study, laboratory loose mix oven aging was compared to field aging to begin calibration for a medium-term oven aging (MTOA) protocol. Five different oven aging temperatures were implemented at different durations to evaluate the change in chemical and rheological aging parameters for four plant-produced asphalt concrete (AC) mixes. The sulfoxide (SUL) index failed to show a consistent trend with aging for extracted binders obtained from both loose mixes and field slabs. The carbonyl area (CA) index was found to show a linear trend with the binders’ rheological parameters. The results of the field calibration indicate that loose mix oven aging of 20 h at 100 °C can simulate field aging at 0.5–0.6 in. (12 mm to 15 mm) depth after six years of pavement life in the climate region and for the material tested. Based on these results for a hot climate, loose mix aging of 20 h at 100 °C was proposed as the MTOA protocol for AC mixes for future studies.

A circular economy based on symbiotic relationships among sectors, where the waste from one is resource to another, holds promise for cost-effective and sustainable production. This research explores such a model for the agriculture, energy, and construction sectors in California. Here, we develop new an understanding for the synergistic utilization mechanisms for rice hull, a byproduct from rice production, as a feedstock for electricity generation and rice hull ash (RHA) used as a supplementary cementitious material in concrete. A suite of methods including experimental analysis, techno-economic analysis (TEA), and life-cycle assessment (LCA) were applied to estimate the cost and environmental performance of the system. TEA results showed that the electricity price required for break even on expenses without selling RHA is $0.07/kWh, lower than the market price. As such, RHA may be available at little to no cost to concrete producers. Our experimental results showed the viability of RHA to be used as a supplementary cementitious material, meaning it can replace a portion of the cement used in concrete. LCA results showed that replacing 15% of cement with RHA in concrete can reduce carbon dioxide equivalent (CO2e) emissions by 15% while still meeting material performance targets. While the substitution rate of RHA for cement may be modest, RHA generated from California alone could mitigate 0.2% of total CO2e from the entire cement production sector in the United States and 1% in California.

In this research, field slab samples were taken from an asphalt pavement in a hot climate with a design life of 40 years at 2, 4, and 7 years of pavement age to determine aging behavior with time at different depths. The asphalt binders were extracted and recovered to evaluate the aging and fatigue performance of the intermediate layer of the asphalt pavement. The chemical and rheological aging properties of the binders were evaluated using Fourier transform infrared spectroscopy and a dynamic shear rheometer, respectively. The pavement included 25 mm (1 in.) open-graded and 75 mm (2 in.) polymer-modified layers over three intermediate layer lifts. The intermediate layer aging is mostly governed by the connecting air voids and binder content of the asphalt mixes. The variation in aging deeper than 100 mm (4 in.) below the pavement surface was minor because of the absence of heat and access to air, with similar aging parameter values observed for different years of field sampling indicating little to no aging after construction. A good correlation ( R2 values of 0.79–0.92) was observed between the chemical property (carbonyl index) and rheological properties of the extracted binder for the dense-graded asphalt concrete layers between 25 and 100 mm depths. The fatigue performance of these extracted binders was evaluated by performing linear amplitude sweep tests. The results indicate that binder fatigue performance initially improved with moderate levels of aging but started to decline under extreme aging conditions.

In this study, four plant-produced asphalt mixes were considered to evaluate the performance and construction challenges of mixes containing RAP/RAS. Also, asphalt mixes were collected at two different plant-production times for each mix type to monitor the performance variability between lots. A softer base binder (PG 58–22) was used for mixes with RAS compared to the base binder (PG 64–16) used for the control mix (no RAP or RAS) and the mix with only RAP. Use of small dosages of rejuvenators and the softer binder in the RAS mixes were found to show similar performance compared to the control mix with no RAP or RAS. The results obtained from the extracted binders of these mixes indicate that mixes with RAP and RAP/RAS are expected to show higher rutting resistance and slightly lower low-temperature cracking resistance, also shown in the mix rutting and fracture cracking tests. A similar fatigue life was observed for all mixes at low strain levels in the Four-Point Beam test. However, the mix with both RAP and RAS was found to show better fatigue life at high strain levels. Similar performance test results were observed between different lots of the same mix type for most cases. Finally, there were no problems with field mixing, compaction, or finishing of the mixes containing RAP and RAP/RAS.

Moisture-related shrinkage is regarded as one of the phenomena that has the largest impacts on the performance of jointed plainconcrete pavements. Still, most mechanistic-empirical design methods oversimplify or ignore predictions of moisture-relatedshrinkage and its effects on concrete pavements. This study evaluates how moisture-related shrinkage accumulates in concretepavements and the structural response of the concrete pavement slabs to the shrinkage action. The experimental data comefrom six thin concrete overlay of asphalt pavements that were instrumented with sensors to measure the structural andhygrothermal response of the slabs due to temperature and moisture-related actions. After an analysis of the predictions madeby current shrinkage models, a new shrinkage model was developed. This new model, which is based on the incremental-recursive application of the B4 shrinkage model, provided an excellent prediction of the moisture-related shrinkage measured inthe field. In addition, the structural response of the concrete pavement slabs under the moisture-related shrinkage action wasanalyzed using the finite element method (FEM). The FEM analysis based on the standard practice for concrete pavementmechanistic-empirical modeling resulted in unrealistically high tensile stresses. However, much smaller stress values were foundwhen the time-dependent (viscoelastic) behavior of concrete and asphalt was considered.

California has a diverse climate that ranges from desert regions with some of the hottest places in North America to coastal regions with mild climates and cold summers. The selection of the binder's performance grade (PG) in California is based on a climate map that was developed in 2005 using 1960 to 1990 data from the National Climate Data Center (NCDC) analyzed using the Enhanced Integrated Climate Model (EICM) and the Long-Term Pavement Performance (LTPPBind 2.0) software. Climate change is happening all around the world, and California is no exception. Based on observed pavement performance, there was a need to revise the PG map using updated climatic data from various sources. In this study, the PG binder map for California was updated to better predict pavement performance using the latest available weather data. Thirty years of climate data (1991-2019) were considered to update the current binder's PG map. The weather data were collected from two main sources: NCDC and Modern-Era Retrospective Analysis for Research and Applications (MERRA). It was found that pavement structure types and thermal coefficients have insignificant effects on the binder performance grade. Also, it is recommended that the binder high PG for the central valley of California be changed based on the results obtained from analysis using EICM and LTPPBind Online.

This report presents the initial performance of the Woodland SR 113 thin concrete overlay on asphalt (COA) project built in 2018-2019.The project comprises approximately four miles of a two-lane highway. The COA had 6 ft. transverse joint spacing, a slab thickness of 6in., and an asphalt base that was overall in very poor condition. The performance of the project between the date of construction andOctober 2020 is presented in this report. The performance was evaluated by different means, including periodic visual inspections andlongitudinal profiler evaluations; falling weight deflectometer (FWD) testing; real load testing (RLT), where the concrete strains undertruck loading were recorded; and continuous monitoring of slab temperatures and drying shrinkage deformations. Overall, the projectperformed as expected. Visual inspection of the COA did not indicate any cracking, faulting, or other structural distress. FWD and RLTevaluations indicate that the COA structure has remained stable since the construction. While the smoothness varied considerably during the period evaluated in this report, the variation was caused by changes in slab curvature due to thermal gradients through the slab depthand concrete drying shrinkage.

Currently, no performance-related test exists for fatigue cracking for use in routine asphalt mix design to approve job mix formula (JMF) and quality control and quality assurance (QC/QA) in California. The existing four-point bending (4PB) test was developed to evaluate the fatigue performance of asphalt pavement, but it is not necessarily appropriate for use in routine JMF and it is too slow for QC/QA. The objective of this study is to evaluate potential surrogate fatigue performance-related testing methods and identify a test that is simple and easy to perform but also able to provide guidance for asphalt mix design on routine projects and QC/QA on all projects. This report compares potential performance-related tests with 4PB tests for simplicity, repeatability (variability), and their relationship to stiffness and fatigue life. Tests evaluated in this study included the semicircular bend (SCB) test, indirect tensile asphalt cracking test (IDEAL-CT), and fatigue testing on fine aggregate matrix (FAM) mixes with linear amplitude sweep (LAS) analysis. These tests were conducted on a variety of asphalt mixtures. Fracture parameters obtained from SCB and IDEAL-CT tests and fatigue parameters from FAM mixes were included as potential fatigue cracking indicators. Linear regression analysis was used to correlate these indicators with the stiffness and fatigue life from 4PB tests. The comparison analysis demonstrates that SCB and IDEAL-CT tests are providing the same fracture information. Fracture parameters from SCB and IDEAL-CT tests are well correlated with the initial flexural stiffness from 4PB tests, and the initial flexural stiffness has a moderate inverse nonlinear correlation with the fatigue life from the controlled-strain 4PB tests. As the IDEAL-CT test is faster and requires less specimen preparation, the recommendation is that attention focus on this test. All the fracture tests indicate that the Strength parameter has low variability and good correlation with 4PB flexural stiffness and a moderate correlation with flexural fatigue, and it is proposed as a surrogate indicator for flexural stiffness and an indication of fatigue life. The FAM test showed promise regarding matching 4PB fatigue life as well as stiffness. The relationships identified in this study between flexural stiffness and flexural fatigue life and between flexural stiffness and the Strength parameter from the IDEAL-CT tests were used to develop a preliminary approach to using the Strength parameter to place upper and lower boundary limits on the stiffness of mixes for use in routine mix design and QC/QA. Examples of this approach are presented in the appendices based on flexural fatigue testing and on setting of those limits without 4PB tests. The sensitivity of performance for both approaches is demonstrated by mechanistic-empirical simulation using CalME. Recommendations are made to further develop the IDEAL-CT Strength parameter for routine mix design and QC/QA, with limits set following the approach developed in this study. Review of pavement management system field cracking data and indirect tensile strength from the AASHTO T 283 test in Caltrans databases is recommended to help this development. Further development of FAM mixes LAS testing is also recommended.

Full depth recycling (FDR) has emerged as a feasible rehabilitation alternative in California. This study focuses on addressing the economic feasibility of example FDR structures using life cycle cost analysis (LCCA) that included probabilistic and deterministic life cycle agency costs and deterministic life cycle road user costs. Two LCCA case studies were performed to provide an initial understanding of the agency cost variation. Estimating roadway construction costs plays a key role in pavement LCCA and long-term planning. Materials costs per functional unit are the major input values affecting pavement cost and total construction cost, and they are dependent on project scale, market, region, risk, climate, and economic circumstances. Publicly available contract cost data from past roadway construction activities on the California state highway network were used in this study. Economies of scale suggest that high quantities of materials would have lower unit costs. Unsupervised machine learning techniques were employed to divide the available data into four volume categories (low, medium, high, very high) based on material quantities in a project to accomplish the probabilistic LCCA. Work zone delay road user costs were estimated in RealCost-CA and incorporated into the life cycle cost of each alternative. Case studies were conducted for rehabilitation of two California highways, State Route 113 (SOL 113) and State Route 84 (YOL 84), for a 60-year design life. Two different pavement rehabilitation alternatives were considered for the project, an FDR structure and a hot mix asphalt HMA reconstruction, along with their respective maintenance and rehabilitation sequences. Two different pavement structural design methods were also included in the study to enable comparison: R-value and CalME.

Procurement of more environmentally sustainable materials for civil infrastructure can be supported using environmental product declarations (EPDs). An EPD is a standardized label that is a scientifically sound way to communicate the potential environmental impacts and selected resource use and waste production flows from all or part of the life cycle of a product. To be called a Type III EPD, the life cycle assessment (LCA) for products used in civil infrastructure must be performed in accordance with ISO standards and the relevant product category rule (PCR) for the product type. Most EPDs for civil infrastructure materials in North America are “cradle-to-gate”, i.e., they include the impacts from the extraction of raw materials from the earth and end at the point at which the product is ready to leave the gate of the last manufacturing location. The steps leading to publication of an EPD include: 1) Developing the PCR, 2) Developing the LCA for the EPD, 3) Creating the EPD, and 4) Verification and publishing of the EPD. Industry-average, regional-average, product-specific, and facility-specific EPDs—with differing specificity to a particular product—are used for different purposes. EPDs are a source of data for materials impacts for use in assessment of the complete life cycle. They provide information to identify changes in impacts that can be made early in the materials production. They also can be used to help procure lower impact materials. This white paper discusses benefits of using EPDs and makes recommendations for improving their validity. Several areas needing improvement in current use in procurement are identified and recommendations are presented for improving the use of cradle-to-gate EPDs in transport infrastructure construction materials procurement and to provide input to complete life cycle pavement LCA to support decision-making.View the NCST Project Webpage

Using post-consumer carpet calcium carbonate (PC4) in concrete can support a circular economy. Three treatments were evaluated to engineer PC4: furnacing at 600°C, furnacing at 900°C, and milling. Specimens were made with 5 and 15% PC4 replacement for Portland cement and were compared to controls with limestone filler replacement and with only Portland cement. Mortars with PC4 treated at 600°C exhibited 28-day compressive strength comparable to controls. X-ray diffraction and Fourier-transform infrared spectroscopyR show heat treatments led to compositional shifts and removal of polymers. Cumulatively, heat treatments can improve the characteristics of PC4 and could benefit both waste utilization and concrete production.

Use of recycled materials, such as reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS), is gaining widespread interest. Currently the California Department of Transportation standard specifications do not allow the use of RAS and limit the use of RAP contents to a maximum of 25% by dry weight of aggregate, though there is a non-standard special provision that allows use of up to 3% RAS by mass of aggregate and 40% RAP content by binder replacement. Nevertheless, mixes with high RAP and RAS are being produced across California for local agencies and commercial use. This study investigated the performance of four plant-produced high RAP or RAS mixes collected from different regions in California. The mixes were not designed and produced following Caltrans specifications. However, they provide insight into the effects of silo storage time on blending of virgin and RAP binder, the performancerelated properties of these mixes, and the measurement of properties by accepted performance-related tests. The mixes were collected before silo storage and after hours in the silo. Testing of the mixes included the following tests: four-point flexural beam stiffness and fatigue, Hamburg Wheel-Track (HWT), confined and unconfined repeated load triaxial (RLT), semicircular bending (SCB), and indirect tensile asphalt cracking test (IDEAL-CT). Additional testing was also conducted on the fine aggregate matrix (FAM) mixes to characterize fatigue and stiffness. This report presents preliminary findings from this study, including results related to the effects of silo storage time on stiffness, cracking resistance, and rutting resistance using performance-related tests as well as an initial comparison of the results from alternative cracking test types for these mixes. The results showed that silo storage time can increase stiffness on the order of 50% to 60%, with corresponding negative effects on fracture resistance and controlled-strain flexural fatigue life. The fatigue performance of the mixes reduced with increased silo storage, particularly at high strain levels, as measured by the flexural beam test. Use of a high rejuvenator dose could also potentially lead to rutting problems and poor fatigue performance. The FAM mix testing showed promising results in terms of characterizing fatigue. However, in its current form, it is not yet practical for use as a quality control/quality assurance test. The recommendation is that the effect of aging and blending of high RAP or RAS mixes be further investigated to understand the full impact of silo storage on these types of mixes. Performance-related specifications should consider the variation in mix properties due to silo storage.

The California Department of Transportation (Caltrans) has been using full-depth recycling (FDR) as a pavement rehabilitation strategy since 2001. Early projects were recycled with foamed asphalt and cement. Cement-only treatments were permitted from 2015 to improve the properties of more marginal materials. However, shrinkage cracking associated with the hydration and curing of the cement-treated layers remains a concern, especially with regard to crack reflection through asphalt concrete surfacings and the related problems caused by water ingress.Crack mitigation has been studied for decades, and a range of measures related to improved mix designs and construction practices have been implemented by road agencies. One of the most promising measures, used in conjunction with appropriate mix designs, is that of microcracking the cement-treated layer between 48 and 72 hours after construction. In theory, this action creates a fine network of cracks in the layer that limit or prevent the wider and more severe block cracks typical of cement-treated layers. Limited research to assess microcracking as a crack mitigation measure has been completed on a number of projects in Texas, Utah, and New Hampshire. Recommendations from these studies were first implemented by the Texas Department of Transportation and then later by other state departments of transportation. However, longer-term monitoring on a range of projects in Texas, California, and other states had revealed that microcracking has not always been successful in preventing cracking. Some projects showed reflected transverse and block cracks in a relatively short time period, attributable to a number of factors including but not limited to cement content, cement spreading, the method of curing, and the interval between base construction and placement of surfacing.Discussions with researchers in Texas indicated that additional research was necessary to better understand the microcracking mechanism, and to identify the key factors influencing performance, including but not limited to aggregate properties, cement content, the time period before microcracking starts, layer moisture contents, roller weights and vibration settings, the number of roller passes, the field test methods and criteria used to assess the degree of microcracking, and the effects of early opening to traffic. A multiphase project was therefore initiated at the University of California Pavement Research Center (UCPRC) to investigate these outstanding issues. The second phase of this study is discussed in this report. This phase covered the design, construction, monitoring, and associated laboratory testing of a 37-cell test road to evaluate shrinkage crack mitigation procedures. The study found that microcracking is an effective mitigation measure, provided that design strengths do not exceed 600 psi (4.1 MPa) and that microcracking is done between 48 and 56 hours after compacting the layer.

A pilot project for the inclusion of recycled asphalt shingles (RAS) in hot mix asphalt (HMA) was built on State Route 49 in El Dorado County in November 2021. Four mixes were included in short test sections: (1) a control mix with no RAS or recycled asphalt pavement (RAP), (2) a typically used mix with 10% RAP that was also used for construction of the rest of the overall project, (3) a mix with 3% RAS, and (4) a mix with 10% RAP and 3% RAS. This technical memorandum presents the laboratory test results from plant mix produced for job mix formula (JMF) verification and from two quality assurance (QA) samples taken during test section construction as well as observations of plant production and construction. The results showed that the mixes submitted for JMF verification and tested as part of QA all met the two performance-related specifications. Most of the QA samples had binder and mix testing results that were similar to or better than those of the JMF verification samples, though there were exceptions. There were no major problems during production or placement of the mixes. The existing roadway has highly variable thicknesses of remaining HMA after milling, and the remaining original HMA has transverse, wheelpath, and block cracks.

The aging of asphalt concrete is mainly governed by the aging of the asphalt binder, which is a naturally occurring organic hydrocarbon. Both chemical and rheological properties of asphalt binder are expected to change as aging continues. The pavement industry is increasing the use of different recycled materials in the construction and rehabilitation of flexible pavements to preserve natural resources, save costs, and reduce environmental emissions. The aged binder from recycled materials is expected to alter the binder properties and its aging characteristics in the new mix. In this study, 3 different virgin base binder types (PG 64-16, PG 58-22, and PG 70-10) and 7 different binder blends containing recycled binders (up to 100 % binder replacement) were subjected to different aging conditions. The rheological and chemical properties of these binders were characterized using a dynamic shear rheometer and Fourier transform infrared spectroscopy, respectively. It was found that the Glover-Rowe parameter distinctively captured the change in binder rheological properties with aging for the different binder blends. A good correlation (R2value of 0.83-1.00) was observed between binder chemical and rheological properties. The source and performance grade of the base binder were found to govern the correlation between the rheological and chemical properties of the blended binder. Hamburg wheel tracking (for rutting and moisture sensitivity) and indirect tensile asphalt cracking test (for fracture) tests were conducted on asphalt mixes maintaining the same blended binder ratios. The laboratory mix performance parameters were found to correlate well with the properties of the blended binders. Therefore, properties of the blended binders can be an important source of information for predicting the performance of asphalt mixes containing recycled materials.

An Environmental Justice (EJ) analysis was carried out using full Chemical Transport Models (CTMs) over Los Angeles, California, to determine how the combination of domain size and spatial resolution affects predicted air pollution disparities in present day and future simulations when data support from measurements is not available. One set of simulations used the Weather Research and Forecasting (WRF) model coupled with Chemistry (WRF/Chem) with spatial resolution ranging from 250 m to 36 km, comparable to census tract sizes, over domains ranging in size from 320 km2 to 10,000 km2. A second set of simulations used the UCD/CIT CTM with spatial resolution ranging from 4 km to 24 km over domains ranging in size from 98,000 km2 to 1,000,000 km2. Overall WRF/Chem model accuracy improved approximately 9% as spatial resolution increased from 4 km to 250 m in present-day simulations, with similar results expected for future simulations. Exposure disparity results are consistent with previous findings: the average Non-Hispanic White person in the study domain experiences PM2.5 mass concentrations 6-14% lower than the average resident, while the average Black and African American person experiences PM2.5 mass concentrations that are 3-22% higher than the average resident. Predicted exposure disparities were a function of the model configuration. Increasing the spatial resolution finer than approximately 1 km produced diminishing returns because the increased spatial resolution came at the expense of reduced domain size in order to maintain reasonable computational burden. Increasing domain size to capture regional trends, such as wealthier populations living in coastal areas, identified larger exposure disparities but the benefits were limited. CTM configurations that use spatial resolution/domain size of 1 km/103 km2 and 4 km/104 km2 over Los Angeles can detect a 0.5 μg m-3 exposure difference with statistical power greater than 90%. These configurations represent a balanced approach between statistical power, sensitivity across socio-economic groups, and computational burden when predicting current and future air pollution exposure disparities in Los Angeles.

This report summarizes the work completed to develop the concrete overlay on asphalt (COA) tables of the new Caltrans Highway Design Manual (HDM) Rigid Pavement Design Catalog. The tables consider the different pavement structures that are candidates for rehabilitation with COA with short transverse joint spacing on the Caltrans road network. The tables were developed using Pavement ME (version 2.5.5) with the nationally calibrated COA cracking model. Pavement ME inputs were determined by considering the state’s climate, traffic, materials, and construction practices. The design tables reflect the recommendations from previous Caltrans research about COA, including slab size, shoulder type, and load transfer efficiency. The Pavement ME inputs for developing the tables include a design life of 20 years, 10% target cracking, and 95% design reliability. The tables will be included in the printed version of the new HDM Rigid Pavement Design Catalog.

This report summarizes the work conducted to develop the jointed plain concrete pavement (JPCP) tables of the new Caltrans HighwayDesign Manual (HDM) Rigid Pavement Design Catalog. The tables consider the different pavement structures that are expected toperform properly on the Caltrans road network. The tables were developed using Pavement ME (version 2.5.5) with the nationallycalibrated transverse cracking model. Pavement ME inputs were determined by considering the state’s climate, traffic, materials, andconstruction practices. A design life of 40 years, 10% target transverse cracking, and 95% design reliability were chosen for developmentof the tables. Transverse joint faulting and the International Roughness Index (IRI) were also determined for the sections in the JPCPtables using Pavement ME (version 2.5.5) nationally calibrated models and compared to Caltrans faulting and IRI limits of 0.15 in. and170 in./mi., respectively. The tables will be included in the printed version of the new HDM Rigid Pavement Design Catalog.

“Complete streets” are those designed not only to accommodate private vehicles, but also to enable safe access for all users, including pedestrians, bicyclists, and transit riders of all ages and abilities. Complete streets can contribute to increased transportation choices, economic revitalization, improved return on infrastructure investments, livable communities, improved safety, improved public health through promotion of active transportation, greenhouse gas reductions, and improved air quality. In 2018, researchers developed a life cycle assessment (LCA) framework for complete streets to enable planners and policymakers to quantify environmental and social impacts over the life cycle of a complete streets project. In this follow-on project, the researchers applied the framework to three case studies covering urban, suburban and rural/suburban regions/conditions. The researchers assessed whether the LCA framework was useful in identifying whether a complete street delivered or, in the case of a proposed project, was likely to deliver, the intended performance and benefits, and the social and health conditions of the neighborhoods receiving the benefits.View the NCST Project Webpage

Weigh-in-motion (WIM) devices measure and record highway vehicle axle loads. The data they collect include axle loads and spacing, vehicle classification and gross weights, and travel speed. These WIM data are used for pavement design, management, and performance studies. In 2016, there were 123 WIM devices operating on sites throughout the California state-owned highway network, one of the densest and best maintained in the United States. The University of California Pavement Research Center (UCPRC) has studied California’s WIM data with the California Department of Transportation (Caltrans) since 2007 to advance mechanistic-empirical (ME) pavement design procedures. Previously, the UCPRC completed the first analysis of the WIM data collected from 1998 to 2003 to discover similarities in axle load distributions at the WIM sites and then grouped them using cluster analysis to generate default traffic inputs for pavement design software. For this research, the UCPRC processed WIM data collected from 80 California WIM-measuring sites from 2004 to 2015, identified the axle load distribution for each site, and updated the earlier grouping using hierarchical cluster analysis. A decision tree was developed to classify WIM data into five WIM axle load spectra, which have been implemented in the Caltrans pavement management system database, PaveM, to generate truck traffic inputs in the CalME and Mechanistic-Empirical Pavement Design Guide (MEPDG) pavement design software tools used by Caltrans for asphalt and concrete pavement design, respectively.

The objective of this study was to develop a framework for determining the fuel use and environmental impacts caused by construction work zones (CWZs) on a range of vehicles and to produce initial calculations of these impacts by modeling traffic closure conditions for highway maintenance and rehabilitation (M&R) activities. The framework was developed and demonstrated in several scenarios. The study included three common highway categories—freeways, multi-lane highways, and two-lane highways—and common California vehicle types. The framework uses realistic drive cycle values and CWZ operation scenarios as inputs to the simulation software MOtor Vehicle Emission Simulator (MOVES) to estimate total fuel consumption and air pollutant emissions. In this study, the framework was demonstrated using three CWZ operations under different traffic congestion levels: light, medium, and heavy.Fuel consumption and pollutant emissions results obtained for the CWZ operation scenario with and without congestion were compared with those for a no-CWZ, no-congestion scenario. In the simulation results for a freeway with a CWZ and heavy congestion, fuel consumption increased by 85% and the CO2 equivalent (CO2-e) emissions increased by 86%, NOx by 62%, SOx by 85%, and PM2.5 by 128%. In the multi-lane highway scenarios, fuel consumption increased by 85%, and CO2-e emissions increased by 88%, NOx by 75%, SOx by 87%, and PM2.5 emissions by 129% for a CWZ with heavy congestion. Lessening traffic congestion in a CWZ from heavy (average speed 5 mph) to medium (average speed 25 mph for a freeway section and 15 mph for a multi-lane road section) reduced fuel consumption by 40% on a freeway and 33% on multi-lane highway.This study also included use of a pilot car in a CWZ on a two-lane road. This approach was undertaken to estimate the possible benefits of different CWZ lane closure strategies and traffic management plans. The pilot-car operation scenario results indicate that a one-lane closure with pilot-car operation on a two-lane road might consume 13% more fuel because of idling time and the slow movement of vehicles following the pilot car. This scenario generated emissions increases of 10% for CO2-e, 14% for NOx, 13% for SOx, and 65% for PM2.5.The results of these scenarios indicate that the impacts from heavy vehicles far exceed those from smaller vehicles in CWZs. Phase 2 of the study will develop methods for pavement management, conceptual evaluation, and project design that consider construction closures by implementing this life cycle assessment framework. These methods will also be used in studies to evaluate pavement design lives (20 years versus 40 years) and pavement selection for truck lanes and in-place recycling and to evaluate lane closure schedules and tactics to minimize CWZ impacts on highways by using project-specific traffic congestion levels.

In late 2015, Caltrans requested that 26 recently constructed concrete projects be tested for smoothness in terms of the International Roughness Index (IRI). The stated purpose was to observe measured IRI on projects accepted after a standard special provision (SSP) change that Caltrans made in 2013 and that was incorporated into the 2015 Construction Contract Standards. The projects provided 52 test sections for evaluation, consisting of three types of paving work: (1) diamond grind on existing pavement, (2) new continuously reinforced concrete pavement, and (3) new jointed plain concrete pavement. The project plans had completion dates from May 2010 to December 2014, and contract acceptance dates from April 2014 to October 2015. Caltrans did not identify which projects had the new SSP or specification change in its contract documents. The IRI data were collected from October 2016 to December of 2016. The IRI data collected included the effects of paving, any corrective grinding required to meet contract acceptance, and the increased roughness caused by traffic over post-construction periods of one to more than two and a half years. At the time of testing in 2016, the UCPRC test vehicle was equipped with a point laser in the left wheel path and a wide spot laser in the right wheel path. The data presented in this technical memorandum are primarily from the wide spot laser because the current standards require the wide spot laser. In general, the IRI measured by a point laser can be unduly increased due to the surface texture of the pavement, which is part of the reason for moving toward a wide spot laser. The construction specification considers both wheel paths and not just the right wheel path tested in this project. The IRI data using the wide spot laser in the right wheel path alone showed that 22% of the 0.1 mi. long sections met the construction standard of 60 in./mi. when measured one to two and a half years after construction. Based on the results from the right wheel path and the wide spot laser, 67% of the right wheel path sections are in good condition with IRI values between 60 and 94 in./mi., 28% are in acceptable condition with IRI values between 95 and 170 in./mi., and 5% are in poor condition with IRI values of 170 in./mi. or greater. Although Caltrans did not identify which projects included the new specification, a trend was observed that projects completed later had lower IRI values than those completed several years earlier.

“Complete streets” is a design concept for primarily urban streets and intersections (existing and/or new) intended to encourage active transportation by bicyclists and pedestrians by making streets safer, convenient, and attractive for active transportation; motorized transportation and parking are also accommodated in the design concept. The social and economic performance indicators included in the social life cycle assessment (SLCA) framework that was used in this project provide a great deal of insight into specific and different potential benefits of a given complete streets project. The SLCA framework is based on five categories of concerns and 17 performance measures or indicators. The indicators were tested in the project and evaluated for final recommendations for use in future studies. The results are compared with the existing streets that were configured to be vehicle-centric. The case studies were solicited in more and less advantaged neighborhoods so that the framework could also be evaluated in different contexts. Use of the CalEnviroScreen tool from the California Environmental Protection Agency was also investigated to assess the exposure of neighborhoods and their vulnerability to environmental impacts in conjunction with the performance indicators when evaluating the potential benefits for disadvantaged neighborhoods (also called priority population areas). As was found in the preceding study, the primary environmental impacts come from the use stage, namely changes in vehicle travel and changes in vehicle speeds from complete street design features. Recommendations are made for dropping some indicators because of difficulties collecting data or interpreting the results, modifications of other indicators, and adding some new indicators to fill important gaps.View the NCST Project Webpage

This document provides guidance on conducting site investigations for new highway construction and widening, rehabilitation, and reconstruction of existing roads. Site investigation is an important part of the pavement design process. This guide has been developed as an integral part of the mechanistic-empirical pavement design procedures for new pavement and rehabilitation and reconstruction of existing pavement. An investigation requires four steps: (1) the preliminary site investigation and desktop data collection, (2) the detailed site investigation and data collection for design, (3) the site investigation data analysis, and (4) the project investigation report.

The goal of this project, titled “Quieter Pavement Monitoring,” is to continue measuring noise and smoothness on previous concretepavement surfacing techniques and the new grind and groove (GnG) surface, and on continuously reinforced concrete pavement (CRCP).Previous studies have initiated the investigation into both the noise properties of GnG and CRCP. This project gathered data in 2016 andearly 2017 on the performance of these concrete pavements in terms of noise and smoothness. These data will be added to the noisedatabase to further the development of specifications, guidelines, and standardized field test methods toward quieter pavements. TheGnG technology on test sections in Caltrans pilot projects was evaluated in terms of measured tire/pavement noise, smoothness, friction,and surface drainability. The results of this study are to be used to further incorporate quieter pavement research into standard Caltranspractice and may serve as a basis for changes in quieter pavement policy and specifications. This report presents the results of testingcompleted in 2016 and 2017 on sections first tested in 2012 and 2013. Recommendations include continued monitoring of GnG,considering use on CRCP, and continued use of diamond grinding. Additional testing will be performed between 2017 and 2020.

Spurred in part by state-level climate policies, California cities and counties have released climate action plans (CAPs) over the last decade to set emissions reduction targets and outline actions that will help meet those goals. However, the state provides little guidance to jurisdictions on how to produce these plans. The range of information included in CAPs varies dramatically across jurisdictions. Additionally, little is known about how jurisdictions transition from the planning to the implementation phase of climate action, or what major factors influence their decision-making process. Other state laws promote emissions reductions in disadvantaged communities, highlighting the importance of making equity a key consideration in CAPs.Researchers at the University of California, Davis assessed and scored over 30 CAPs released between 2009 and 2020 based on the degree to which they addressed three themes: emissions reductions, cost, and equity. The researchers also surveyed local agency staff from 25 California jurisdictions with published CAPs about the importance of different factors during climate action planning and implementation, the inclusion of equity impacts in CAPs, sources of funding, and more. Finally, the researchers developed a set of guiding questions to assist jurisdictions in developing CAPs that include equity considerations both broadly and by specific sector. This policy brief summarizes the findings from that research and provides policy implications.View the NCST Project Webpage