Traffic Roadways Research Articles

Metals stress on soil enzyme activities and herbs defense in the vicinity of high traffic roadways.

This study has investigated the impact of vehicle sourced heavy metals (HMs) on soil enzyme activities and plants in and around high traffic roadways near the metropolitan area. In detail, the defense response against HM pollution was studied by considering the commonly available herbs around the roadside area namely Alternanthera paronychioides, Ageratum conyzoides, Spilanthes acmella, and Parthenium hysterophorus. The study reported that the HM concentrations such as Cu, Ni, Zn, Mn, and Cr were observed in the range of 6.05 ± 0.1 to 309 ± 0.5mg/kg in roadside soil and 5.2 ± 0.1to 451 ± 4.2mg/kg in the herbs collected from roadside area. The soil enzyme (urease, dehydrogenase, amylase, catalase, peroxidase, and polyphenol oxidase) activities decreased by 22.56 to 77.84% in roadside soil and lower IC50 values were observed for DPPH (2.32-4.67) and H2O2 (1.59-2.15) free radical scavenging activities in plants collected from roadside area. The flavonoid and phenolic content in plants collected from the roadside area ranges from 12.65 ± 0.2 to 15.75 ± 0.3mg quercitin/g and 0.61 ± 0.04 to 1.16 ± 0.1mg gallic acid/g respectively while in plant collected from the control areas ranges from 7.96 ± 0.1 to 11.24 ± 0.05 and 0.47 ± 0.01 to 0.61 ± 0.1. In addition, the contamination factor (CF) (1.53-11.92) and geo-accumulation index (Igeo) (0.031-2.99) in soil and bioaccumulation factor (BAF) (0.72-2.73) of Cu, Ni, Zn, Mn, and Crin plants indicated that the soil and plants growing along the highway were heavily contaminated with HM. Finally, Pearson correlation matrix confirmed the inhibition effect of HM on soil enzymatic activities and enzymatic defense of plants in response to the HM stress.

Air Pollution, Ultrafine Particles, and Your Brain: Are Combustion Nanoparticle Emissions and Engineered Nanoparticles Causing Preventable Fatal Neurodegenerative Diseases and Common Neuropsychiatric Outcomes?

Exposure to particulate matter (PM) pollution damages the human brain. Fossil fuel burning for transportation energy accounts for a significant fraction of urban air and climate pollution. While current United States (US) standards limit PM ambient concentrations and emissions, they do not regulate explicitly ultrafine particles (UFP ≤ 100 nm in diameter). There is a growing body of evidence suggesting UFP may play a bigger role inflicting adverse health impacts than has been recognized, and in this perspective, we highlight effects on the brain, particularly of young individuals. UFP penetrate the body through nasal/olfactory, respiratory, gastrointestinal, placenta, and brain-blood barriers, translocating in the bloodstream and reaching the glymphatic and central nervous systems. We discuss one case study. The 21.8 million residents in the Metropolitan Mexico City (MMC) are regularly exposed to fine PM (PM2.5) above the US 12 μg/m3 annual average standards. Alzheimer's disease (AD), Parkinson's disease (PD), and TAR DNA-binding protein (TDP-43) pathologies and nanoparticles (NP ≤ 50 nm in diameter) in critical brain organelles have been documented in MMC children and young adult autopsies. MMC young residents have cognitive and olfaction deficits, altered gait and equilibrium, brainstem auditory evoked potentials, and sleep disorders. Higher risk of AD and vascular dementia associated with residency close to high traffic roadways have been documented. The US is not ready or prepared to adopt ambient air quality or emission standards for UFP and will continue to focus regulations only on the total mass of PM2.5 and PM10. Thus, this approach raises the question: are we dropping the ball? As research continues to answer the remaining questions about UFP sources, exposures, impacts, and controls, the precautionary principle should call us to accelerate and expand policy interventions to abate or eliminate UFP emissions and to mitigate UFP exposures. For residents of highly polluted cities, particularly in the developing world where there is likely older and dirtier vehicles, equipment, and fuels in use and less regulatory oversight, we should embark in a strong campaign to raise public awareness of the associations between high PM pollution, heavy traffic, UFP, NP, and neuropsychiatric outcomes, including dementia. Neurodegenerative diseases evolving from childhood in polluted, anthropogenic, and industrial environments ought to be preventable.

Flexural Performance and Toughness Characteristics of Geogrid-Reinforced Pervious Concrete with Different Aggregate Sizes.

Pervious concrete is an environmentally friendly paving material to reduce surface runoff in urban construction. However, due to low flexural strength and cracking susceptibility caused by the high porosity, pervious concrete is only used in low-volume traffic roadways and parking lots for current service. This study investigated the permeability, strength, and flexural performance of pervious concrete with different coarse aggregate size, geogrid position, and geogrid layer number. Test results indicate that the geogrid placed at an appropriate position in pervious concrete improved the permeability and compressive strength. Four-point bending tests were conducted in the laboratory to evaluate the flexural performance and toughness characteristics of pervious concrete beam. Meanwhile, this study also proposed a new evaluation method to distinguish the contribution of geogrids and concrete mixture to the flexural toughness of pervious concrete beam at the pre-peak and post-peak stages by two toughness indices. Test results indicate that geogrids improved the flexural strength, deformability, and energy absorption capability of pervious concrete beam. The geogrids placed at both one-third and two-thirds of the heights of pervious concrete beam resulted in the optimum flexural performance. Besides, the small size (5–10 mm) aggregates were conducive to providing high flexural strength for the geogrid-reinforced pervious concrete beam, while the large size (10–15 mm) aggregates played a significant role in obtaining noteworthy post-cracking performance.

Modeling of Driver Behavior on Trajectory–Speed Decision Making in Minor Traffic Roadways With Complex Features

The selection of trajectory and speed is a crucial factor in automobile driving behavior. However, almost all the research objects of existing Driver models are developed for driving on city streets and general highways but are not applicable to driving simulations on minor traffic roads with complex shapes, in particular. Therefore, according to the practical automobile driving processes and characteristics in the real world, this paper proposed a trajectory calculation strategy, which we named as “selecting trajectory point on a preview cross section.” According to this strategy, objective functions was established to describe the different selection patterns of “trajectory and speed” of drivers. Constraint expressions were then designed on the basis of the roadway geometry and pavement condition, passenger car performance and ride comfort. A rolling-horizon algorithm for simultaneous solving, i.e., “target trajectory-target speed,” was proposed. Eventually, validations of the proposed model were conducted using a race circuit and a complex mountain road as a simulation example, and the results indicated that the anticipated computational results could be obtained using the proposed decision-making model and algorithm. The result also showed a fairly good agreement with the trajectory and speed of a car on a practical circuit and mountain road.

Developing air exchange rate models by evaluating vehicle in-cabin air pollutant exposures in a highway and tunnel setting: case study of Tehran, Iran.

The passengers inside vehicles could be exposed to high levels of air pollutants particularly while driving on highly polluted and congested traffic roadways. In order to study such exposure levels and its relation to the cabin ventilation condition, a monitoring campaign was conducted to measure the levels inside the three most common types of vehicles in Tehran, Iran (a highly air polluted megacity). In this regard, carbon monoxide (CO) and particulate matter (PM) were measured for various ventilation settings, window positions, and vehicle speeds while driving on the Resalat Highway and through the Resalat Tunnel. Results showed on average in-cabin exposure to particle number and PM10 for the open windows condition was seven times greater when compared to closed windows and air conditioning on. When the vehicle was passing through the tunnel, in-cabin CO and particle number increased 100 and 30%, respectively, compared to driving on highway. Air exchange rate (AER) is a significant factor when evaluating in-cabin air pollutants level. AER was measured and simulated by a model developed through a Monte Carlo analysis of uncertainty and considering two main affecting variables, vehicle speed and fan speed. The lowest AER was 7h-1 for the closed window and AC on conditions, whereas the highest AER was measured 70h-1 for an open window condition and speed of 90kmh-1. The results of our study can assist policy makers in controlling in-cabin pollutant exposure and in planning effective strategies for the protection of public health.

Identification of accident-prone sections in roadways with incomplete and uncertain inspection-based information: A distributed hazard index based on evidential reasoning approach

Identification of accident-prone road segments based on the results of safety inspection is a widely accepted method for prioritization of safety improvement efforts particularly for low volume traffic roadways. In the existing methods, the items listed in a risk factor checklist are given qualitative or exact scores and then risk items are aggregated without considering the uncertainty in the subjective judgment of the inspector. Other shortcomings include the failure to consider the relative importance of risk factors and the failure to provide a solution to deal with absence or incompleteness of data. This study introduces a method of road safety evaluation and a distributed hazard index (DHI) based on evidential reasoning approach. This approach allows the risk factor to be expressed by several degrees with different values of confidence instead of one definite figure. By adjustment for the extent of user exposure and the approach of road safety authority to improvement, the distributed index is turned into the Hazard Index (HI), which serves as measure for final prioritization of road sections. The proposed method is applied to a case study and the resulting sections ranking show good consistence with the results of empirical Bayesian method based on accident records.

Economic Analysis of Pavement Preservation Techniques

This paper summarizes the research study conducted to develop and implement a methodological framework, using an economic analysis technique, to evaluate the cost effectiveness of the three different preventive maintenance treatments applied to roadways in Texas: chip seals, microsurfacing, and thin overlays. The analysis is based on a stochastic evaluation of the effective life and cost of more than 14,000 maintenance and rehabilitation projects undertaken from 1994 to 2015. The effect of traffic loads, traffic volume, and roadway type was also evaluated. The life-cycle cost of the preventive maintenance techniques was obtained using a Monte Carlo simulation. Among the principal results, it was found that chip seals are the most cost-effective treatment and present the lowest life-cycle cost variability. The effective life of all three treatments was found to be quite similar. Additionally, it was found that the chip seals and microsurfacing tend to present comparable life-cycle costs when used on heavy traffic roadways.

Assessment of the Physico-Chemical Properties of Waste Cooking Oil and Spent Coffee Grounds Oil for Potential Use as Asphalt Binder Rejuvenators

Recycling of waste is an optional approach across industries to reduce environmental harm and turn it into sustainable and valuable resource alternatives. This paper addresses recycling of food industry waste through exploring potential use to enhance damaged asphalt binder used in roadways. The two wastes, spent coffee grounds and waste cooking oil were subjected to different levels of oxidation after which their physical and chemical properties were analyzed. Results show that oxidation significantly affects the oils by increasing the release of fatty acids and breaking of double bonds. The latter, in addition to polymerization and release of high molecular weight compounds, increases the viscosities of the oils while retaining their Newtonian behavior. As such, oxidation may be able to effectively customize physicochemical properties of oils, namely viscosity, for their reported application as asphalt binder rejuvenators. The rejuvenated binder can then be reused in production of asphalt for low traffic roadways.

Influence of solid noise barriers on near-road and on-road air quality

Abstract Public health concerns regarding adverse health effects for populations spending significant amounts of time near high traffic roadways has increased substantially in recent years. Roadside features, including solid noise barriers, have been investigated as potential methods that can be implemented in a relatively short time period to reduce air pollution exposures from nearby traffic. A field study was conducted to determine the influence of noise barriers on both on-road and downwind pollutant concentrations near a large highway in Phoenix, Arizona, USA. Concentrations of nitrogen dioxide, carbon monoxide, ultrafine particles, and black carbon were measured using a mobile platform and fixed sites along two limited-access stretches of highway that contained a section of noise barrier and a section with no noise barrier at-grade with the surrounding terrain. Results of the study showed that pollutant concentrations behind the roadside barriers were significantly lower relative to those measured in the absence of barriers. The reductions ranged from 50% within 50 m from the barrier to about 30% as far as 300 m from the barrier. Reductions in pollutant concentrations generally began within the first 50 m of the barrier edge; however, concentrations were highly variable due to vehicle activity behind the barrier and along nearby urban arterial roadways. The concentrations on the highway, upwind of the barrier, varied depending on wind direction. Overall, the on-road concentrations in front of the noise barrier were similar to those measured in the absence of the barrier, contradicting previous modeling results that suggested roadside barriers increase pollutant levels on the road. Thus, this study suggests that noise barriers do reduce potential pollutant exposures for populations downwind of the road, and do not likely increase exposures to traffic-related pollutants for vehicle passengers on the highway.

Sound wall barriers: Near roadway dispersion under neutrally stratified boundary layer

With the passage of California Senate Bill 375, which motivates infill development near transit hubs, there is the potential to increase vehicle congestion in residential communities and increase in human exposure to toxic mobile source pollutants. Among all the mitigation strategies that protect near roadway residents from health-affecting vehicular emissions (e.g. separating sensitive receptors from high traffic roadways), this paper discusses the impact of sound wall barriers (SBs) in reducing the air pollution exposure of nearby residents. To date, there have been some studies done to understand the impact of these structures on dispersion of vehicular emissions; however, no definitive conclusion has been drawn yet. The main objective of this paper is to provide more information and details on flow and dispersion affected by barriers through a systematic laboratory simulation of plume dispersion using a water channel. Three sets of experiments were conducted: (1) plume visualizations, (2) plume concentration measurements, and (3) flow velocity measurements. Results from this study shows that the deployment of sound barriers induces a recirculating flow over the roadway which transports the surface released emissions to the upwind side of the roadway, and then shifts the plume upward through an induced updraft motion. Plume visualizations clearly demonstrate that the presence of SBs induce significant vertical mixing and updraft motion on the roadway which increases the initial plume dilution and plume height and consequently results in reduced downwind ground level concentrations. Although different SB configurations result in different localized flow patterns, the dispersion pattern does not change significantly after several SB heights downwind of the roadway.

Partial input to output impacts in DEA: The case of DMU-specific impacts

Data Envelopment Analysis (DEA) is a methodology for evaluating the relative efficiencies of a set of decisionmaking units (DMUs). The original model is based on the assumption that in a multiple input, multiple output setting, all inputs impact all outputs. In many situations, however, this assumption may not apply, such as would be the case in manufacturing environments where some products may require painting while others would not. In earlier work by the authors, the conventional DEA methodology was extended to allow for efficiency measurement in such situations where partial input-to-output interactions exist. In that methodology all DMUs have identical input/output profiles. It is often the case, however, that these profiles can be different for some DMUs than is true of others. This phenomenon can be prevalent, for example, in manufacturing settings where some plants may use robots for spot welding while other plants may use human resources for that task. Consider a highway maintenance application where consulting services for safety corrections may not be employed on low traffic roadways, but are commonly used on high traffic, multilane highways. Thus, input to output links in the case of some DMUs are missing in the case of others. To address this, the current paper extends the methodology presented earlier by the authors to allow for efficiency measurement in situations where some DMUs have different input/output profiles than is true of others. The new methodology is then applied to the problem of evaluating the efficiencies of a set of road maintenance patrols.

Land-use regression modelling of highway ultrafine particle number concentrations

Ultrafine particles (UFP; diameter < 100 nm) are suspended atmospheric solids of concern to human health due to their small diameters. Vehicles emit significant numbers of UFP, leading to steep spatial gradients on, and near, high traffic roadways. Particle number concentrations were measured while driving a cyclic route on four Toronto highways during non-rush hour weekday periods during the summer. These data were averaged over roadway length segments to create a concentration map of the route. Road segment-averaged concentrations were bimodal, and ranged from 26,000 to 106,500 particles cm-3, which is significantly greater than the average background downtown Toronto concentration (15,500 cm-3). A land-use regression model incorporating diesel truck traffic, six land use types, and distance to Lake Ontario, accounted for 34% of the variability of on-road concentrations. Understanding the complex spatial distribution of urban UFP is integral to designing epidemiological studies and understanding commute...

Abstract TP176: Residential Proximity to High Traffic Roadways is Associated with Post-Stroke Mortality

Background: Living in areas with higher pollution has been associated with incidence of ischemic stroke and higher rates of all-cause mortality. There is considerable interest in the relative role of traffic related pollution specifically, but less is known about the relationship between traffic related pollution and long term survival after stroke. We hypothesized that living closer to a busy roadway is associated with a higher rate of post-stroke mortality in the Boston area. Methods: We identified 1763 consecutive patients age ≥21 years admitted to Beth Israel Deaconess Medical Center with neurologist-confirmed ischemic stroke between April 1, 1999 and October 31, 2008 and residing in the Boston metropolitan area. The Social Security Death Index was used to identify deaths through June 2012. We obtained average daily traffic counts from the Massachusetts Department of Transportation and geocoded patients’ addresses to determine distance to the nearest roadway averaging ≥10,000 vehicles/day. Categories of residential distance were defined as ≤100 meters (m), 100 to ≤200 m, 200 to ≤400 m or &gt;400 m from a busy roadway. Models were adjusted for demographics, medical history, and socioeconomic factors. Results: Among 1682 stroke patients with complete data, there were 826 deaths [median follow up = 4.6 years]. We observed a higher rate of post-stroke mortality among people living closer to high traffic roadways. Patients living ≤100 m from high traffic roadways had a 23% (95% CI: 2%, 49%) higher rate of post-stroke mortality than patients living &gt;400 m away (Figure, p-trend=0.04). Conclusions: In this study, living close to a busy roadway was associated with an elevated mortality rate. This relationship remained statistically significant after adjustment for individual and neighborhood level factors, providing further evidence of the association between traffic-related pollution and mortality in a susceptible population.

Intelligent Traffic Light Flow Control System Using Wireless Sensors Networks

Vehicular traffic is continuously increasing around the world, especially in large urban areas. The resulting congestion has become a major concern to transportation specialists and decision makers. The existing methods for traffic management, surveillance and control are not adequately efficient in terms of performance, cost, maintenance, and support. In this paper, the design of a system that utilizes and efficiently manages traffic light controllers is presented. In particular, we present an adaptive traffic control systembased on a new traffic infrastructure using Wireless Sensor Network (WSN) and using new techniques for controlling the traffic flow sequences. These techniques are dynamically adaptive to traffic conditions on both single and multiple intersections. A WSN is used as a tool to instrument and control traffic signals roadways, while an intelligent traffic controller is developed to control the operation of the traffic infrastructure supported by the WSN. The controller embodies traffic system communication algorithm (TSCA) and the traffic signals time manipulation algorithm (TSTMA). Both algorithms are able to provide the system with adaptive and efficient traffic estimation represented by the dynamic change in the traffic signals' flow sequence and traffic variation. Simulation results show the efficiency of the proposed scheme in solving traffic congestion in terms of the average waiting time and average queue length on the isolated (single) intersection and efficient global traffic flow control on multiple intersections. A test bed was also developed and deployed for real measurements. The paper concludes with some future highlights and useful remarks.

Characterizing Urban Traffic Exposures Using Transportation Planning Tools: An Illustrated Methodology for Health Researchers

Exposure to elevated levels of vehicular traffic has been associated with adverse cardiovascular and respiratory health effects in a range of populations, including children, the elderly, and individuals with pre-existing heart conditions, diabetes, obesity, and genetic susceptibilities. As these relationships become clearer, public health officials will need to have access to methods to identify areas of concern in terms of elevated traffic levels and susceptible populations. This paper briefly reviews current approaches for characterizing traffic exposure and then presents a detailed method that can be employed by public health officials and other researchers in performing screening assessments to define areas of potential concern within a particular locale and, with appropriate caveats, in epidemiologic studies examining traffic-related health impacts at the intra-urban scale. The method is based on two exposure parameters extensively used in numerous epidemiologic studies of traffic and health-proximity to high traffic roadways and overall traffic density. The method is demonstrated with publically available information on susceptible populations, traffic volumes, and Traffic Analysis Zones, a transportation planning tool long used by Metropolitan Planning Agencies and planners across the USA but presented here as a new application which can be used to spatially assess possible traffic-related impacts on susceptible populations. Recommendations are provided for the appropriate use of this methodology, along with its limitations.

Identification and Initial Characterization of Prominent Air Pollution Sources and Respiratory Health at Secondary Schools in Ibadan, Nigeria

Objective. Research on air quality in and around schools, and the associated vulnerability of school-age children, is limited in less developed countries (LDCs), particularly Africa. The main objective of this study was to conduct an initial assessment of sources of air pollution in and around schools as a surrogate for air quality and report adverse health effects among students at selected secondary schools in urban Ibadan, Nigeria. Methods. The study was a descriptive cross-sectional survey involving eight secondary schools selected purposively, defined with eight acronyms (listed alphabetically): ABHS, AGS, BOHS, CDSS, IGS, LC, MGS, and OAHS. We used pre-tested, self-administered questionnaires, observational checklists to assess certain environmental health indicators, and interviews. The questionnaire was divided into five sections including environmental and health conditions. A total of 400 students from senior secondary classes, 50 from each school, were selected through stratified random sampling. Results. The school's location, especially if close to high traffic roadways, contributed to reported perceived poor air quality of school environments. The majority of students believed air pollution sources in the school environment were mainly refuse burning and car emissions from nearby roadways. Cough and asthma were the most frequently reported adverse health outcomes. The highest prevalence of reported recent asthma episodes (symptoms) were recorded at BOHS (84%) and at CDSS (62%); furthermore, at ABHS it was nearly 1-in-2 students and at OAHS about 1-in-5 students. BOHS and OAHS each reported over 10% for prevalence of bronchitis. Conclusions. Proximity of study schools to certain sources and activities such as refuse burning and major roadways seemed to present substantial risk factors for reported respiratory morbidity among secondary students in urban Ibadan, Nigeria. Future research should quantify source emissions and exposure and further characterize frequency and severity of respiratory symptoms, among other parameters, at schools in Nigeria and other sprawling urban areas of Africa.

Influence of Various Material and Traffic Inputs on Flexible Pavement Design Methods for Alabama Roadways

Statistical analyses of over 2,000 pavement designs using the 1993 American Association of State Highway Transportation Officials Design Guide was conducted. Variations in traffic levels, and subgrade, base, and hot mix asphalt (HMA) moduli and thickness showed that the only significant material and traffic design inputs were the subgrade modulus and the initial ESAL loads. A plus or minus 5% change in the design traffic level did not statistically influence the determination of the structural number (SN). A subgrade modulus of 3,000 psi and a linear growth rate of 4% for roadways with annual average daily traffic of more than 10,000 is recommended for determining the SN. The growth rate for lower traffic volume roadways will vary significantly between 0 and 3%. A more limited evaluation of the 2002 Design Guide showed that a mechanistic–empirical method of flexible pavement design is strongly influenced by the HMA thickness and the distribution of truck types within the annual average daily traffic. Sele...

Evidence for Adverse Reproductive Effects of Exposure to Traffic-Related Air Pollution—Are Pregnant Women at Risk?

MS7-15 Abstract: Evaluating the influence of traffic-related air pollutants on adverse birth outcomes in Southern California, we previously reported 10% to 20% increases in risk of term low birth weight (LBW) and preterm birth in infants born to women living close to heavy traffic roadways or being exposed to high levels of ambient CO and/or PM10 during sensitive periods of gestation (third trimester). The effects observed for CO, PM10, and traffic density might be attributable to toxins sorbed to primary exhaust particles such as polycyclic aromatic hydrocarbons (PAHs). With more recent data, we mapped subject home locations at birth, estimated distance-weighted traffic density (DWTD), and, in addition, determined the number of trucks on freeways within 750 feet of each residence. Although our data for births during 1994–1996 clearly linked DWTD to these outcomes, for the later period (1997–2000), associations between DWTD and preterm birth remained only for women who lived in poorer neighborhoods (relative risk [RR] = 1.08; 95% 95% confidence interval [CI]: 1.00–1.18) or who experienced their third trimester during the fall/winter months (RR = 1.07, 95% CI: 0.99–1.16, highest compared with lowest quintile). Yet, we newly observed a 23% greater risk of preterm and LBW birth among women with ≥13,290 freeway trucks passing within 750 feet of their residence per day (odds ratio: 1.23, 95% CI: 1.06–1.43). This suggests more heavily polluting vehicles within the overall cleaner motor vehicle fleet such as trucks may now be more important for these outcomes. For ambient CO, PM10, and PM2.5, we examined whether residential distance from monitoring stations affected risk estimates because local pollutant heterogeneity may be inadequately captured by ambient stations. For women residing within 1 mile of a station, we observed larger increases in risk for adverse pregnancy outcomes with high third-trimester pregnancy CO or particle exposures than for women living at larger distances from stations. These results confirmed our suspicions that it is important to address local heterogeneity for traffic-related pollutants in Los Angeles when assessing their impact on pregnancy outcomes. Land use regression (LUR) models informed by short-term and dense monitoring for traffic pollutants (typically NOx) may present the best next step in improving exposure assessment beyond these simple traffic metrics or relying on ambient air monitoring measures alone. Residential and personal monitoring of key exhaust pollutants (ultrafine particles, PAHs, hopanes, steranes) in addition to more “traditional” exhaust markers (CO, NOx) in subsamples of women might help to further elucidate the importance of motor vehicle emissions for these outcomes.

Vehicular Air Pollution, Playgrounds, and Youth Athletic Fields

In spite of epidemiological evidence concerning vehicular air pollution and adverse respiratory/cardiovascular health, many athletic fields and school playgrounds are adjacent to high traffic roadways and could present long-term health risks for exercising children and young adults. Particulate matter (PM1,0.02–1.0 μm diameter) number counts were taken serially at four elementary school athletic/playground fields and at one university soccer field. Elementary school PM1 measurements were taken over 17 days; measurements at the university soccer field were taken over 62 days. The high-traffic-location elementary school field demonstrated higher 17-day [PM1] than the moderate and 2 low traffic elementary school fields (48,890 ± 34,260, 16,730 ± 10,550, 11,960 ± 6680, 10,030 ± 6280, respective mean counts; p < .05). The 62-day mean PM1 values at the university soccer field ranged from 115,000 to 134,000 particles cm− 3. Lowest mean values were recorded at measurement sites furthest from the highway (∼34,000 particles cm− 3) and followed a second-order logarithmic decay (R2 = .999) with distance away from the highway. Mean NO2 and SO2 levels were below 100 ppb, mean CO was 0.33 ± 1.87 ppm, and mean O3 was 106 ± 47 ppb. Ozone increased with rising temperature and was highest in the warmer afternoon hours (R = .61). Although the consequence of daily recess play and athletic activities by school children and young athletes in high ambient [PM1] conditions has not yet been clearly defined, this study is a critical component to evaluating functional effects of chronic combustion-derived PM exposure on these exercising schoolchildren and young adults. Future studies should examine threshold limits and mechanistic actions of real-world particle exposure.

Development of Stabilizer Selection Tables for Low-Volume Roads: Arlington, Texas

Expansive soil movements cause damage to low-volume traffic roadways, which is attributed to the low rigidity of the materials used in the pavements. Several treatment methods have been used to stabilize expansive, soft subsoils, which have yielded mixed results due to the presence of sulfates. Because of the ambiguity of these results, the city of Arlington, Texas, established a task force of researchers and practitioners in the area of soil stabilization to develop matrix tables of the various treatment methods and their applicability to stabilize expansive, soft, and sulfate-rich soils. Extensive literature compiled on the stabilizers, several new and previous research studies on stabilizers, and the expertise of the task group members were considered in the evaluation process. The task force developed seven matrix-form selection tables that showed various treatment methods and if their applications were acceptable or unacceptable for the 12 types of soft and sulfate-rich subgrade soils. A summary of the tables was prepared, along with guidelines on how to use these tables to screen the potential stabilizers for pavement construction projects.