Showing papers in "Civil Engineering Studies, Illinois Center for Transportation Series in 2013"

Experimental investigation of the seismic response of bridge bearings.

Abstract: The Illinois Department of Transportation (IDOT) commonly uses elastomeric bearings to accommodate thermal deformations in bridges. These bearings also present an opportunity to achieve a structural response similar to isolation during seismic events. IDOT has been developing an earthquake resisting system (ERS) to leverage the displacement capacity available at typical bearings in order to provide seismic protection to substructures of typical bridges. The research program described in this report was conducted to validate and calibrate IDOT’s current implementation of design practice for the ERS, based on experiments conducted on typical full-size bearing specimens, as well as computational models capturing full bridge response. The overall final report is divided into two volumes. This first volume describes the experimental program and presents results and conclusions obtained from the bearing and retainer tests. The experiments described in this volume provide data to characterize force-displacement relationships for common bearing types used in Illinois. The testing program comprised approximately 60 individual tests on some 26 bearing assemblies and components (i.e., retainers). The testing program included (1) Type I elastomeric bearings, consisting of a steel-reinforced elastomeric block vulcanized to a thick top plate; (2) Type II elastomeric bearings, distinct from Type I bearings with a steel bottom plate vulcanized to the bottom of the elastomeric block, and a flat sliding layer with polytetrafluoroethylene (PTFE) and stainless steel mating surfaces between the elastomer and the superstructure; and (3) low-profile fixed bearings. Tests conducted to simulate transverse bridge motion also included stiffened L-shaped retainers, consistent with standard IDOT practice. Tests were conducted using monotonic and cyclic displacement protocols, at compression loads corresponding to a range of elastomer compression stresses from 200 to 800 psi. Peak displacements from initial position ranged from 7-1/2 in. to 12-1/2 in., depending on bearing size. Test rates were generally quasi-static, but increased velocities up to 4 in./sec were used for bearings with PTFE and for a subset of other elastomeric bearings. On the basis of all of the experimental findings, bearing fuse force capacities have been determined, and appropriate shear stiffness and friction coefficient values for seismic response have been characterized and bracketed.

Bridge decks: mitigation of cracking and increased durability

Abstract: This report discusses the application of expansive cements (Type K and Type G) and shrinkage-reducing admixtures (SRAs) in reducing the cracking due to drying shrinkage. The Type K expansive cement contained portland cement and calcium sulfoaluminate-based component whereas the Type G expansive system was made of portland cement and calcium oxide (CaO)-based component. The restrained expansion test in accordance with ASTM C 878 demonstrated that Type K and Type G concretes had minimal shrinkage at the end of 100 days. The Type K bridge deck model also exhibited a reduction in tensile strain on the order of 40-50 microstrains and reduction in excess shrinkage potential which showed its effectiveness in reducing the tensile stress due to drying shrinkage. The effect of mineral admixtures on expansion characteristics of Type K and Type G system is also discussed. The effectiveness of SRA was assessed using ASTM C 1581 that clearly showed the delay in cracking time due to addition of an SRA. The increase in SRA dosage reduced the drying shrinkage, but also resulted in reduction of compressive strength.

Investigation of methods and approaches for collecting and recording highway inventory data.

Abstract: Many techniques for collecting highway inventory data have been used by state and local agencies in the United States These techniques include field inventory, photo/video log, integrated global positioning system/geographic information system (GPS/GIS) mapping systems, aerial photography, satellite imagery, virtual photo tourism, terrestrial laser scanners, mobile mapping systems (ie, vehicle-based light detection and ranging (LiDAR), and airborne LiDAR) These highway inventory data collection methods vary in terms of equipment used, time requirements, and costs Each of these techniques has its specific advantages, disadvantages, and limitations This research project sought to determine cost-effective methods to collect highway inventory data not currently stored in Illinois Department of Transportation (IDOT) databases for implementing the recently published Highway Safety Manual (HSM) The highway inventory data collected using the identified methods can also be used for other functions within the Bureau of Safety Engineering, other IDOT offices, or local agencies A thorough literature review was conducted to summarize the available techniques, costs, benefits, logistics, and other issues associated with all relevant methods of collecting, analyzing, storing, retrieving, and viewing the relevant data In addition, a web-based survey of 49 US states and 7 Canadian provinces has been conducted to evaluate the strengths and weaknesses of various highway inventory data collection methods from different state departments of transportation To better understand the importance of the data to be collected, sensitivity analyses of input variables for the HSM models of different roadway types were performed The field experiments and data collection were conducted at four types of roadway segments (rural two-lane highway, rural multi-lane highway, urban and suburban arterial, and freeway) A comprehensive evaluation matrix was developed to compare various data collection techniques based on different criteria Recommendations were developed for selecting data collection techniques for data requirements and roadway conditions

Thermal Behavior of IDOT Integral Abutment Bridges and Proposed Design Modifications

Abstract: The Illinois Department of Transportation (IDOT) has increasingly constructed integral abutment bridges (IABs) over the past few decades, similar to those in many other states. Because the length and skew limitations currently employed by IDOT have not necessarily been based on rigorous engineering analyses, an extensive 3-D parametric study has been performed, complemented by installation of field monitoring equipment on two recently constructed bridges, to potentially expand the use of IABs in Illinois. Some notable findings from this study include: (1) IAB configuration with extreme skew (> 60°) can perform well with proper detailing; (2) H-pile webs oriented parallel to the longitudinal axis of the bridge, regardless of skew, substantially reduces weak-axis bending; (3) compacted backfill reduces pile stresses; (4) live loads affect thermally induced pile stresses; (5) longer intermediate spans tend to increase pile stresses; and (6) time-dependent behaviors, such as concrete shrinkage, may significantly influence maximum pile stresses. Based on these findings, a more rigorously developed set of recommendations for maximum IAB lengths and skews in Illinois are proposed.

Effects of a nonuniform subgrade support on the responses of concrete pavement.

Abstract: Intelligent compaction is gaining attention for its ability to spatially map the compaction effort of a pavement support layer, and it has also been shown to be able to detect areas of nonuniform compaction, which raises the issue of what the effects of a nonuniform support condition are on the stresses and deflections in a rigid pavement This study considered multiple nonuniform support conditions, including theoretically generated and predetermined and randomly assigned from measured field data The slabs and nonuniform support conditions were modeled using two-dimensional and three-dimensional finite element methods with input variables being axle type, curling, and lateral and longitudinal axle movements Overall the study found that certain nonuniform support conditions and axle positions can significantly increase the peak tensile stress in the slab over even uniform soft support In particular, a single slab with soft longitudinal edge support and a slab with “randomly” assigned nonuniformities were critical cases that increased the peak slab tensile stresses When the slab was modeled with preexisting through-length surface cracks, it was found that the nonuniform soft edges support conditions would result in unstable crack growth based on the significant increase in the stress intensity factor When modeling a set of concrete slabs over a nonuniform support based on field data, the peak tensile stresses were increased relative to a uniform support based on the location of the wheel load relative to the nonuniformity and also based on the adjacent differences in nonuniform soil stiffness The field data was also statistically reassigned by normal and beta distributions to predefined area sizes, which demonstrated that with a normal distribution, the probability of low k-values along the pavement edge increased thereby raising the probability of higher peak tensile stresses Overall, certain nonuniform support of concrete slabs can produce much higher tensile stresses than a uniform support condition, particularly when considering different loading positions and curling conditions, soft support along the pavement edge, and preexisting cracks

Improvement for Determining the Axial Capacity of Drilled Shafts in Shale in Illinois

Abstract: In this project, Illinois-specific design procedures were developed for drilled shafts founded in weak shale. In addition, recommendations for field and laboratory testing to characterize the in situ condition of weak shales in Illinois were developed and presented herein. For this project, weak shale is defined as an intermediate geologic material (IGM) with an unconfined compressive strength of 10 to 100 ksf. These investigation and design improvements are anticipated to lead to safer design and substantial deep-foundation cost savings for the Illinois Department of Transportation.

Seismic Performance of Quasi-Isolated Highway Bridges in Illinois

Abstract: The Illinois Department of Transportation (IDOT) commonly uses elastomeric bearings to accommodate thermal deformations in bridges, and these bearings have potential utility in seismic events. IDOT has developed an Earthquake Resisting System (ERS) using the displacement capacity of typical bearings to achieve a structural response similar to isolation. Project R27-70 was conducted to validate and calibrate the quasi-isolated ERS based on full-scale laboratory tests of bearings and computational models capturing full-bridge seismic response. The overall report is divided into two volumes. Volume 1 discussed the experimental program. This second volume focuses on the analytical program but also contains retainer design recommendations. Results from the experimental testing program were used to develop constitutive bearing models, which were incorporated into the finite element model of a three-span bridge with simply supported abutments and fixed bearings at one pier. A suite of 48 bridges was created to represent the most common highway bridge configurations in Illinois. Variables included superstructure type, pier type, pier height, elastomeric bearing type, and foundation flexibility. Two sets of ten synthetic ground motions from the New Madrid Seismic Zone were scaled to match the AASHTO seismic design spectra for Cairo, Illinois, and applied in the longitudinal and transverse directions. A total of 12,000 nonlinear dynamic analyses were conducted in OpenSees at six scale factors from 0.5 to 1.75 and used to create coarse incremental dynamic analyses. On the basis of the findings of the parametric study, most bridges in Illinois would not experience severe damage during a 75-year design life, and bearing unseating or span loss are not likely to occur in regions with moderate seismic hazard. Piers with fixed bearings commonly yielded for small earthquakes, but future calibration of fuse capacities may improve this behavior.

Safety benefits of implementing adaptive signal control technology: survey results

Abstract: The safety benefits and costs associated with implementing adaptive signal control technology (ASCT) were evaluated in this study. A user-friendly online survey was distributed to 62 agencies that had implemented ASCT in the United States. Twenty-two agencies responded to the survey, providing information about the system type, detection type, and cost of ASCT implementation. These agencies were from city governments (47%), state governments (29%), and county governments (24%). They represented both a wide range of ASCT implementation rates (from 1 to 700 intersections) and five of the most popular ASCT systems. There was a range of ASCT costs for different systems and detection types used with the system. The average cost per intersection to the agencies that responded was $38,223 when cost data from all agencies were included, but it was $28,725 when the cost data from agencies with the lowest and highest figures were excluded. Detailed volume and geometry data were provided by the respondents for six specific intersections. Crash data were provided for three of these six intersections. Each of the three intersections exhibited a crash reduction, but the sample size was too small for statistical testing. The observed ASCT cost per intersection per annual crash reduction was computed for the three intersections, and it ranged from $5,444 to $37,500. The scope of this study was very limited; thus, only very limited conclusions could be drawn. The limited data seem to indicate that there are safety benefits for implementing ASCT. It is recommended that a controlled experiment of ASCT implementation in Illinois be conducted to determine benefit–cost ratios and compute a crash modification factor (CMF).

Modeling Seniors' Activity-Travel Data

Abstract: The United States is experiencing an increase in its elderly population. According to Census Bureau estimates, this population should increase by 104.2% from 2000 to 2030, which translates into 72.1 million elders by 2030. This demographic change will affect the transportation system, like any other socioeconomic system. Thus, this study seeks to understand the dynamics of elderly activity-travel behavior and its potential effects on the transportation system to better identify and meet seniors’ transportation needs. The Urban Travel Route and Activity Choice Survey (UTRACS), an automated, Internet- and global positioning system (GPS)-based prompted-recall survey that was coupled with learning algorithms, was employed for that purpose. In this report, the study team analyzes elderly tour formation, activity-trip planning, mode-choice selection, and activity timing.

Evaluating Pavement Markings on Portland Cement Concrete (PCC) and Various Asphalt Surfaces: Results of Year 1, 2, 3, and 4 Data Collection

Abstract: The Illinois Department of Transportation (IDOT) uses a variety of different pavement marking systems and has experienced a wide range of pavement marking performance In an effort to maximize marking performance and to optimize marking selection, IDOT initiated a research project to evaluate the performance of all currently approved marking types to develop a pavement marking selection guide based on performance results The purpose of this project is to evaluate the performance of pavement markings on both portland cement concrete (PCC) and hot-mix asphalt (HMA) pavements over a period of four years Field investigations were conducted to gather data on the durability and visibility of markings and the compatibility between markings and pavement materials From the results of the study and a lifecycle cost analysis, Applied Research Associates (ARA) developed a pavement marking selection guide Because the successful performance of a marking depends largely on controlling many variables during the installation of the marking, this guide includes pavement marking installation inspection methods for use by IDOT inspectors

Flexural Capacity of Rigid Pavement Concrete Slabs with Recycled Aggregates

Abstract: Few studies have focused on the effect of recycled materials on the concrete slab load capacity. This study used virgin and recycled aggregates—fractionated reclaimed asphalt pavement (FRAP) and recycled concrete aggregate (RCA)—and by-product cementitious materials—ground granulated blast furnace slag and fly ash—to cast and test the load capacity of single- and two-lift concrete slabs. Five concrete mixtures were examined, which were virgin aggregate (the control) and four different replacements of coarse aggregate: 45% FRAP, 45% FRAP with macrofibers, 100% RCA, and a blend of 45% FRAP and 55% RCA. For all laboratory specimens tested, the virgin aggregate concrete had the highest strength (compression, split tension, and flexural) and modulus of elasticity, and the mix with 45% FRAP and fibers resulted in the lowest properties, which was attributed to the relatively high air content of the fresh concrete. With the exception of the mix with 45% FRAP and fibers, the critical stress intensity factor and initial and total fracture energies of the recycled aggregate concretes were not statistically different than the virgin aggregate concrete using the single edge notched beam specimen. For the 16 large-scale concrete slabs (6 ft x 6 ft x 6 in. thick) cast using both single and two-lift designs, the results indicated that the concrete slab load-carrying capacity is significantly underpredicted by the beam flexural strength measurements, and that concrete with recycled aggregates had similar flexural load capacity to the virgin concrete slabs. Using 2D finite element analysis, the ratio between slab flexural capacity and beam strength was found to be significantly higher for the recycled aggregate concrete relative to the virgin aggregate concrete. The concrete slab flexural load capacity was governed more by the concrete fracture properties and slab geometry then by conventional strength criteria. Two additional topics presented in the appendices are a literature review and evaluation of recycled washout water (grey water) from concrete batch plants as mixing water in fresh concrete. Based on the literature, grey water should be suitable for use in fresh concrete, provided that the solids content is not excessive and ASTM C1602 guidelines are followed. A laboratory study evaluating the use of recycled tire cord steel as fiber reinforcement in concrete revealed that the fibers could be beneficial for improving the concrete toughness, but a cost-benefit analysis is required.

Development of an Economical, Thin, Quiet, Long-Lasting, High Friction Surface Layer, Volume 1: Mix Design and Lab Performance Testing

Abstract: This project developed and evaluated four new asphalt concrete (AC) mixtures that use locally available aggregates whenever possible with the ultimate goal of a cost-effective mixture that also improves pavement performance. Although numerous tactics have previously been introduced to improve the performance of asphalt pavement, these improvements often add expenses because they use unnecessarily large amounts of high quality aggregates and highly modified binder. The Illinois Department of Transportation initiated a program to develop sustainable asphalt pavements that use locally available aggregates as much as possible to reduce the material cost while also improving performance. These new mixtures were developed using the Bailey method to provide a promising aggregate structure that makes it possible to ensure compactability at thinner layers. The newly developed mixes use locally available natural aggregates such as dolomite, and include smaller amounts of imported materials such as quartzite, steel slag, and fibers to improve their performance in terms of durability, rut resistance, moisture susceptibility, fracture, and complex modulus. To evaluate the performance of each new mixture, five laboratory tests were conducted at the Advanced Transportation and Research Engineering Laboratory (ATREL), and the results suggest a preferred mixture.

Improving the Effectiveness of Nighttime Temporary Traffic Control Warning Devices, Volume 1: Evaluation of Lights on Nighttime Work Zone Channelization Devices

Abstract: Currently, the Illinois Department of Transportation (IDOT) is one of the few state transportation agencies that require warning lights on nighttime work zone channelization devices, such as drums and barricades The intent of the steady-burn, amber warning lights is to increase visibility of the channelization devices, providing guidance to motorists and preventing intrusions into the closed lane However, their additional benefit beyond that provided by the high-reflectivity materials used on the channelization devices themselves has not been evaluated, including taking into consideration their initial, maintenance, and replacement costs; and the environmental and economic issues of routine battery replacement Applied Research Associates, Inc (ARA) studied the effectiveness of warning lights on nighttime channelization devices by reviewing pertinent literature, experimental studies of nighttime work zones with and without lights on drums, driver surveys, and focus groups of driver perceptions and behavior in work zones using traffic drums A cognitive model of driver mental processes was applied to this information to determine the influence of drum warning lights, if any, on driver perception and response The research showed that, when unprompted, most drivers did not perceive a difference or respond any differently in nighttime work zones using lights on drums than in those without lights However, when asked to make direct comparisons between work zones with and without lights on drums, there was a slight preference for lights on drums due to the perceived increase in nighttime lighting they provide Nighttime work zones, and work zones in general, are visually cluttered environments; and the presence (or absence) of lights on drums was not significant enough to attract the drivers’ attention, given competing visual cues such as work zone traffic control devices, other vehicles, and activities in the work space In addition, the reflective prismatic sheeting on drums in Illinois provides sufficient visibility without warning lights

WorkZoneQ User Guide for Two-Lane Freeway Work Zones

Abstract: WorkZoneQ was developed in Visual Basic for Applications (VBA) to implement the results of the previous study, “Queue and Users’ Costs in Highway Work Zones.” This report contains the WorkZoneQ user guide. WorkZoneQ consists of eight Excel worksheets and input data are traffic information, geometric characteristics, traffic control plan, and value of time figures. Then WorkZoneQ determines the capacity and computes queue length, delay, users’ costs, and congestion duration. It also determines the intervals that do not satisfy Illinois Department of Transportation (IDOT) mobility standards. Eight example problems were solved. The first one is a basic example to obtain the above output data. The successive examples show the capability of the program to handle different time interval lengths, variation of volume within the interval, flagger presence, police presence, change in work intensity, temporary roadway blockage, and different speed limits. Three workshops were conducted for IDOT engineers and their feedback was used to further improve the program. The current version of the program was developed using field data collected from 2-to-1 freeway work zones and it is recommended that a future project expand the program for other lane configurations.

Restoration progress and flood disturbance at IDOT wetland mitigation sites.

Abstract: As required under Section 404 of the Clean Water Act and the Illinois Interagency Wetland Policy Act of 1989, the Illinois Department of Transportation (IDOT) has established wetlands at mitigation sites throughout Illinois to compensate for impacts to natural wetlands by road construction. One of the mechanisms for meeting regulatory obligations is to mitigate wetland impacts through restoration or creation of wetlands that provide functions similar to natural wetlands, under the federal policy goal of “no net loss” of wetland area and function. Progress toward restoring wetland functions is measured through the use of prescribed performance standards issued by state and federal regulatory agencies. In most cases, these performance standards contain measures of quality, health, and structure of wetland plant communities. The majority of extant Illinois wetlands and most IDOT wetland mitigation sites are located in floodplain areas and are exposed to varying degrees of flooding, depending on their location within a given watershed, their position within the floodplain setting, and their climate zone within the state. Among the major challenges in attaining vegetation-based performance standards at IDOT wetland mitigation projects are poor plant-community quality (e.g., low species richness) and mortality of planted trees. Although floodplain wetlands are supported by regular flooding, floods can also produce excessive sediment, cause ice damage, and result in prolonged inundation—leading to mortality in wetland plants, thereby interrupting expected trajectories of succession and progress toward achieving mitigation performance standards. In this study, the authors analyzed data collected by the Illinois Natural History Survey and the Illinois State Geological Survey during past and current site monitoring to examine the influence that flooding has on ecological mechanisms that lead to variation in the performance levels among a large number of floodplain compensatory mitigation wetlands. The goals of the analyses were to evaluate the influence that flooding has on (1) plant-community quality at the landscape scale and (2) species turnover within plant-community functional groups at wetland mitigation sites. For the first component of the analysis, simple linear regression was used to evaluate the influence of flooding on the levels of ten plant-community metrics. Results of linear regression analysis showed significant, inverse relationships between mean annual flood exposure and average levels of three of the ten plant-community metrics: species richness, floristic quality index (FQI), and proportion of perennial species. Also, hierarchical mixed models were used to evaluate the influence of flooding on loss and subsequent gain of species within seven species functional groups. Mixed models showed significant correlation of the loss of species within all species groups with magnitude of flood intensity in the same year, and the gain of non-hydrophytic, annual, and non-native species with magnitude of flood intensity in the preceding year. Results of this study indicate two general tendencies at IDOT wetland mitigation sites: (1) Higher average magnitudes of flooding will lead to decreased species richness, floristic quality, and proportion of perennials in floodplain settings and significantly decrease the likelihood of attaining performance standards based on these metrics; and (2) higher-magnitude floods will tend to disrupt succession by eliminating the species groups that are associated with higher-quality plant communities and allow more undesirable species to colonize in the year following flood disturbance. These tendencies highlight the importance of considering flood-disturbance regime, when evaluating the quality of plant communities in floodplain wetlands. Additionally, planted-tree counts and mapping were conducted to provide a baseline for future tree-survival studies at three sites. Potential future studies would track survivorship of each tree species in response to flood disturbance.

Field evaluation of smart sensor vehicle detectors at railroad grade crossings -- volume 3 : performance in favorable weather conditions.

Abstract: The performance of a microwave radar system for vehicle detection at a railroad grade crossing with quadrant gates was evaluated in adverse weather conditions: rain (light and torrential), snow (light and heavy), dense fog, and wind. The first part of this report compares the results of the modified system setup in adverse weather conditions with those from good weather conditions (as presented in Volume 3 of this study). Then, the results of a re-modified system setup were compared to the results for the modified system setup in good and adverse weather conditions. The re-modification was in response to increased detection errors in adverse weather conditions. With the modified setup, system performance was sensitive to the adverse weather conditions. In torrential rain, false calls increased to 24.82%–27.08% (e.g., May 28 and June 1) when there was some traffic on the crossing. However, when there was torrential rain but only one vehicle (e.g., May 31) or no traffic flow (e.g., June 10), the radar units generated 15 false calls on each of those 2 days. For all heavy snow datasets combined, missed calls by a single radar unit and by the two radar units working as a combined unit (i.e., systemwide) represented 13.51% and 11.66% of the loop calls, respectively. The most severe snow effects were found during freezing rain/ice. In dense fog, false calls increased to 11.58%, and all false calls were generated when the gates were moving or in the down position. Wind did not affect system performance, and the errors were similar to those in good weather conditions. With the re-modified setup, the frequency of errors in heavy rain and heavy snow conditions was reduced and system performance was similar to the good weather, light rain, and light snow conditions. In heavy rain, false calls in the re-modified setup were reduced to 2.6% compared with 30.5% in the modified setup. This reduction was the result of a significant decrease in the false calls generated without objects in the crossing. The re-modified setup eliminated the systemwide missed calls in heavy snow. The re-modified setup also reduced the false calls to less than 1% in good weather, light rain, and light snow conditions and practically had no missed, stuck-on, or dropped calls. Results indicate that re-modifications improved the performance of detection system.

Improving the Effectiveness of Nighttime Temporary Traffic Control Warning Devices, Volume 2: Evaluation of Nighttime Mobile Warning Lights

Abstract: Vehicle-mounted warning lights for nighttime mobile highway operations provide critical protection to workers and the driving public. Alerting the traveling public of the approaching work activity and providing guidance is vital to maintaining safety and mobility. Previous research conducted for IDOT on mobile lane closures (Steele and Vavrik 2009) identified driver confusion as a concern to the safety of nighttime highway operations. Users are subject to warning lights from multiple agencies with varying characteristics and configurations, but we know little about driver comprehension of these signals and their influence on driver behavior. Applied Research Associates, Inc. (ARA) studied the effectiveness of warning lights on nighttime highway operations, including mobile lane closures, incident responses, and police activities, by reviewing pertinent literature, performing observational and experimental field studies, and conducting driver surveys and focus groups of driver perceptions and behavior in response to nighttime mobile operations. The authors used a cognitive model of driver mental processes to analyze this information and better understand the interaction between warning lights and driver perception and behavior, and to identify and evaluate potential improvements to current practice. The research showed that drivers view current vehicle-mounted warning lights as highly visible, attention-getting, and effective at conveying the message caution/alert. However, intense lights can cause discomfort glare and multiple light sets on individual vehicles, or multiple vehicles at a location, can be distracting, annoying, or anxiety-inducing. Complex visual scenes can confuse drivers and take longer to process cognitively, leading to slower reaction times. Often, information provided by flashing arrows, signs, and changeable message signs can be interfered with by other warning lights on the same vehicle. Suggestions for improvement from the focus groups centered primarily on reducing the number of flashing lights, or synchronizing their flashing, on individual vehicles, reducing the intensity of specific lights, sequential flashing of arrows between multiple trucks in a convoy, and incorporating directional motion in light bars. Researchers were not able to test some of the ideas due to limitations of current device technology; however, field experiments on several suggested concepts showed the potential to improve driver perception, comprehension, and behavior by modifying the number, intensity, and synchronization of lights on individual vehicles, as well as between vehicles.

Development of an Economical Thin, Quiet, Long-Lasting, High Friction Surface Layer for Economical Use in Illinois, Volume 2: Field Construction, Field Testing, and Engineering Benefit Analysis

Abstract: This project provides techniques to improve hot-mix asphalt (HMA) overlays specifically through the use of special additives and innovative surfacing technologies with aggregates that are locally available in Illinois. The ultimate goal is to improve pavement performance through optimized materials while also controlling cost by efficiently using local materials. Therefore, the proposed new mixes use locally available aggregates when possible. The project also considered the use of alternative aggregates such as steel slag to increase the friction quality of the HMA and therefore improve pavement performance. To evaluate the newly developed wearing course mixtures and evaluate their performance under actual traffic loading, test pavements were constructed, including control mixtures, between August and November 2010 in northern Illinois. The newly proposed mixtures include fine dense-graded HMA and stone matrix asphalt (SMA). The fine dense-graded HMA was designed using the Bailey method and developed with the hope of improved compactability for thinner asphalt layers. The SMA contained a 4.75-mm nominal maximum aggregate size (NMAS) that allows for layers as thin as 0.75 in. On-site performance tests were conducted at 4-month intervals following construction; the tests include noise, friction, rutting, and texture profiling. An engineering benefit analysis was performed to evaluate the new mixes’ cost effectiveness. New HMAs are proposed, along with alternative cross-sections that improve pavement performance while controlling costs.

Evaluation of Traffic-Flow Monitoring Technologies: Cicero-Midway Smart Corridor Case Study

Abstract: The original goal of this project was to (1) collect probe-vehicle and sensor data in the region of interest, and perform cleaning and map matching of the data; and (2) evaluate the accuracy of multiple technologies, either through direct comparison with ground truth (probe vehicles) when data are available or through simulation where direct measurement data were unavailable. Due to a substantial and unexpected lack of spatiotemporally coinciding measurement and ground-truth data, the project changed direction midway, to quickly capitalize on technology developed in the earlier stages and to attempt to remedy the underlying problem that led to the present difficulty: the unavailability of substantial and low-cost travel-time measurements. Under this new direction, the project was successful. A prototype system for low-cost traffic-flow measurement using Wi-Fi transmission monitoring has been developed and successfully demonstrated, A survey of efficient vehicle-tracking methods was performed, comparing over 100 alternative methods, leading to the development of a significantly more accurate and cost-effective method. Finally, technology developed in the early stages of the project were repurposed to facilitate the creation of the UIC Shuttle Tracker.

Fatigue Performance of Brass Breakaway Light Pole Couplings

Abstract: Breakaway couplings connect light pole bases to foundation anchor bolts and are intended to fracture on impact after vehicle collision to protect drivers and passengers from severe injury. The coupling consists of an internally threaded hollow hexagon made of half‐hard CDA 360 brass with a thread‐locked stainless steel stud. Several designs of the notched hexagonal shaped coupling were tested in bending by attaching them to a simulated pole tube and base and then inducing stresses by deflection of the tube by a hydraulic jack. Individual couplings were also fatigued in axial tension‐compression by a servo‐controlled universal testing machine. Using the data obtained, the axial tension‐compression fatigue relationship for the brass couplings was ΔS = 433N–0.153, where ΔS is the alternating stress from tension to compression. Finite element analysis using ABAQUS® found that stress concentrations in the external notch radius and the internal threads were accurate to about 20% of the values obtained from experimental strain gage data. The stress concentration factors for the final design were determined to be Ktt = 10.8 in tension and Ktc = 10.4 in compression. Couplings were fatigue tested in laboratory air at room temperatures in the range of 10,000 to 10,000,000 cycles. Couplings that were exposed to 1000 hr of salt fog prior to fatigue testing showed no difference in fatigue life compared to couplings fatigued in air. Standard structural theory was used to determine the nominal stresses of couplings attached to steel poles subjected to winds of 90 mph. Using an average stress concentration factor Ktavg of 10.6, the peak coupling stress in various orientations of the pole base with respect to the wind direction was determined to be 24.1 ksi. When a more accurate segmental wind pressure method of determining moments acting on the pole base was used, the calculated peak stress was 23.9 ksi. At 90 mph, a +24 ksi to –24 ksi alternating stress develops, resulting in a 50% mean fatigue life estimated at 1,799,000 cycles. Variances in notch section were caused by straightness deviations of hexagon stock and from drilling and tapping operations, averaging 4.2% to a maximum of 9%. The fatigue initiation zone was about 30 degrees of the notch circumference. The probability that four couplings would have only the weakest one facing the maximum wind exposure is 30 degree/360 degree/4, which is about 2% of the time. Maximum wind speeds recorded in Illinois are less than the 90 mph AASHTO requirement. Decreasing notch depth by 9% would lessen the likelihood of premature failure due to insufficient load‐bearing section of the coupling notch.

Stormwater pollution, erosion, and sediment control products demonstration and training center

Abstract: The University of Illinois at Urbana-Champaign (UIUC), the Illinois Department of Transportation (IDOT), and the Construction Engineering Research Laboratory (CERL) of the U.S. Army Corps of Engineers joined in a partnership to develop a training and demonstration facility for erosion and sediment control and stormwater management. With funding from IDOT and in-kind contribution from the Illinois Land Improvement Contractors Association (ILICA), a facility was built on 5 acres of land at the UIUC South Farm. The formal name of this training, demonstration, and research facility is the Erosion and Sediment Control Research and Training Center (ESCRTC). The aim of the center is to provide training and perform research and evaluation of stormwater management, soil erosion control, and sediment control best management practices (BMPs). The center has a field research and demonstration site, along with a field classroom for training. The field site includes a large earthen berm, a pump house, a detention pond, and three channels of varying configurations.

Travel reliability inventory for chicago

Abstract: The overarching goal of this research project is to enable state Departments of Transportation (DOTs) to document and monitor the reliability performance of their highway networks. To this end, a computer tool, Travel Reliability Inventory for Chicago (TRIC), was developed to produce travel reliability inventories from various traffic data sources. In due course, travel reliability inventories will provide necessary inputs to next-generation transportation decision-making tools that are sensitive to travel reliability. TRIC incorporates reliable routing algorithms to construct and rank travel reliability indexes on routes between any given origin-destination pair in the network. It also implements a basic graphical user interface for creating and visualizing travel reliability indexes and archiving them in Esri shape format, which can be read by most geographic information system (GIS) software. Case studies using data from the Chicago area were conducted for demonstration purposes.