Road Traffic Emissions Research Articles

Removing traffic emissions from CO2 time series measured at a tall tower using mobile measurements and transport modeling

In recent years, measurements of atmospheric carbon dioxide with high precision and accuracy have become increasingly important for climate change research, in particular to inform terrestrial biosphere models. Anthropogenic carbon dioxide emissions from fossil fuel burning have long been recognized to contribute a significant portion of the carbon dioxide in the atmosphere. Here, we present an approach to remove the traffic related carbon dioxide emissions from mole fractions measured at a tall tower by using the corresponding carbon monoxide measurements in combination with footprint analyses and transport modeling. This technique improves the suitability of the CO2 data to be used in inverse modeling approaches of atmosphere–biosphere exchange that do not account for non-biotic portions of CO2. In our study region in Oregon, road traffic emissions are the biggest source of anthropogenic carbon dioxide and carbon monoxide. A three-day mobile campaign covering 1700 km of roads in northwestern Oregon was performed during summer of 2012 using a laser-based Cavity Ring-Down Spectrometer. The mobile measurements incorporated different roads including main highways, urban streets, and back-roads, largely within the typical footprint of a tall CO/CO2 observation tower in Oregon's Willamette Valley. For the first time, traffic related CO:CO2 emission ratios were measured directly at the sources during an on-road campaign under a variety of different driving conditions. An average emission ratio of 7.43 (±1.80) ppb CO per ppm CO2 was obtained for the study region and applied to separate the traffic related portion of CO2 from the mole fraction time series. The road traffic related portion of the CO2 mole fractions measured at the tower site reached maximum values ranging from 9.8 to 12 ppm, depending on the height above the surface, during summer 2012.

A bid-rent land-use adaptation model for mitigating road network vulnerability and traffic emissions

Disruptions of vulnerable links in transportation networks have been widely recognized as a serious safety issue, generating both traffic congestion and significant traffic emissions. This paper aims to consolidate a proposed land-use adaptation (LUA) strategy into transportation vulnerability assessment, quantitatively exploring the question about how to optimize spatial patterns in long-term land-use planning to improve network reliability, protect existing vulnerable links and critical locations, and reduce traffic emissions. To mitigate regional network vulnerability, the LUA model employs the bid-rent theory to describe the agents’ behaviors in the land market. Using the genetic and frank-wolf algorithms, this paper analyzes the relationship between link vulnerability and geographical distribution of land-use patterns. The amount of traffic-related CO emissions is used to evaluate the environmental impacts of the vulnerable link closure. The case study indicates that the long-term LUA strategy at land-cell level effectively reduces road network vulnerability, significantly improves the performance of existing urban road systems, and reduces traffic emissions. The model results also show that road networks tend to become more vulnerable with an increase in travel demand. Furthermore, without considering accessibility reduction caused by vulnerable transportation links, the land-use development is more likely to make the existing vulnerable links more susceptible. The proposed LUA methodology could allow urban system managers and planners to take proactive actions, thereby mitigating negative environmental impacts caused by network disruptions rather than being obliged to react to them .

Relating urban airborne particle concentrations to shipping using carbon based elemental emission ratios

This study demonstrates a novel method for testing the hypothesis that variations in primary and secondary particle number concentration (PNC) in urban air are related to residual fuel oil combustion at a coastal port lying 30 km upwind, by examining the correlation between PNC and airborne particle composition signatures chosen for their sensitivity to the elemental contaminants present in residual fuel oil. Residual fuel oil combustion indicators were chosen by comparing the sensitivity of a range of concentration ratios to airborne emissions originating from the port. The most responsive were combinations of vanadium and sulphur concentration ([S], [V]) expressed as ratios with respect to black carbon concentration ([BC]). These correlated significantly with ship activity at the port and with the fraction of time during which the wind blew from the port.The average [V] when the wind was predominantly from the port was 0.52 ng m−3 (87%) higher than the average for all wind directions and 0.83 ng m−3 (280%) higher than that for the lowest vanadium yielding wind direction considered to approximate the natural background. Shipping was found to be the main source of V impacting urban air quality in Brisbane.However, contrary to the stated hypothesis, increases in PNC related measures did not correlate with ship emission indicators or ship traffic. Hence at this site ship emissions were not found to be a major contributor to PNC compared to other fossil fuel combustion sources such as road traffic, airport and refinery emissions.

POSSIBLE USE OF SPIDER WEBS FOR THE INDICATION OF ORGANIC ROAD POLLUTANTS

The results of the research assessing the possibility of using spider webs for the indication of organic pollutants (PAHs) in the long period of time in the air polluted with road traffic emissions are presented. It was proved that webs could be used for the indication of pollutants of this type. Because of the great availability and dense structure of webs belonging to representatives of Agelenidae family, they can serve as a very effective tool. What is more, the secluded location of webs is favorable and influences the accuracy and credibility of results, since deposited pollutants are not washed off with rain, neither are they decomposed by microorganisms or sunlight. The influence of co-existing contaminants is also minimized.

Time-dependent transportation network design that considers health cost

This paper proposes a bi-level optimisation framework for time-dependent discrete road network design that considers health impacts. A general health cost function is proposed and captured in the framework. The function simultaneously considers the health impacts of road traffic emissions, noise, and accidents due to network expansion. To solve the problem, the artificial bee colony (ABC) algorithm is proposed to search the network design solutions of the upper-level problem, while the method of successive averages and the Frank–Wolfe algorithm are adopted to solve the lower-level time-dependent land-use transportation problem. A repairing procedure is proposed to remedy infeasible solutions. A numerical study is set up to illustrate the conflict between maximising consumer surplus and minimising the health cost. This paper also reveals a paradox phenomenon that with an increasing amount of emissions, the health cost decreases. Moreover, the existence of a health inequity between different residential zones is demonstrated. A modified Sioux Falls network is adopted to show the performance of the solution algorithm as well as the effectiveness of the proposed repairing procedure.

Influence of Festival Celebration on Concentrations of PM<sub>2.5</sub>, PM<sub>10</sub>, SO<sub>2</sub> and NO<sub>2</sub> in Shenyang City

The daily pollutant variations of PM2.5, PM10, SO2 and NO2 are useful for environment protection and advices for human health. Two years data from three different time period before Spring Festival (SF), after SF and after Lantern Festival (LF) in Shenyang city of year 2013 and 2014 was analyzed. Results showed that concentrations of PM2.5, PM10, SO2 and NO2 were higher in 2014 than those in 2013, especially for SO2 and NO2; Among the three periods, concentrations of four air pollutants followed the sequence of after LF > before SF > after SF and road traffic emissions are more contributive than firework combustion during the festival celebration. We conclude that air pollution in Shenyang City is worsening and more influenced by vehicular pollution.

Trends of road dust emissions contributions on ambient air particulate levels at rural, urban and industrial sites in southern Spain

Abstract. The impact of road dust emissions on PM10 and PM2.5 (atmospheric particulate matter with diameteer < 10 μm and 2.5 μm mass concentrations recorded from 2003 to 2010 at 11 locations (rural, urban and industrial) in southern Spain was estimated based on the chemical characterization of PM and the use of a constrained Positive Matrix Factorization, where the chemical profile of local road dust samples is used as a priori knowledge. Results indicate that road dust increased PM10 levels on average by 21–35% at traffic sites, 29–34% at urban background sites heavily affected by road traffic emissions, 17–22% at urban-industrial sites and 9–22% at rural sites. Road dust contributions to ambient PM levels show a marked seasonality with maxima in summer and minima in winter, likely due to the rainfall frequency. Decreasing concentration trends over the sampling years were found at some traffic and urban sites but in most cases the decreases were less significant than for vehicle exhaust emissions, while concentrations increased at industrial sites, probably due to local peculiarities. Concerning PM2.5, road dust contributions were lower than in PM10, as expected but still important (21–31%, 11–31%, 6–16% and 7% for traffic, urban background, urban-industrial and rural sites, respectively). In addition the three main sources of road dust (carbonaceous particles, brake wear and road wear/mineral) were identified and their contributions to road dust mass loadings estimated, supporting the idea that air quality managers should drive measures aimed at preventing the build-up of road dust particles on roads.

Calculation model of road traffic noise annoyance rate in urban areas

This paper presents a calculation model for road traffic annoyance based on traffic flow counting, road traffic noise emission measures and public surveys held in the urban area of inner Budapest, Hungary. Based on the research results a new model for the rate of highly annoyed of road traffic noise annoyance was determined, the subjective response of a person to road traffic noise emissions. Exposure to high road traffic noise may deteriorate everyday life and human well-being especially in urban areas with high traffic flow. With the model developed the rate of high annoyance can be predicted for urban traffic circumstances, for a given noise level. This prediction may help authorities to decide whether a road traffic noise complaint is justified or not and whether further measurements are necessary.

Proposal for estimating ground-level ozone concentrations at urban areas based on multivariate statistical methods

This study focuses on describing ozone patterns and estimating ozone concentrations in urban settings through the classification of an urban area into homogeneous typologies, according to hourly ozone concentrations, and the development of accurate estimation models for each typology. For these proposals, a hierarchical cluster analysis was conducted in order to define homogeneous subareas, and multiple linear regressions were subsequently applied with the aim of obtaining ozone predictions, employing chemical and meteorological variables as predictors. Seville metropolitan area (Spain) is a densely populated area of the Mediterranean Basin that exhibits environmental problems related to ozone pollution episodes. Ozone exceedances are a consequence of the combination of road traffic and industry emissions with hot temperatures and high solar radiation, mainly during anticyclonic events. Cluster analysis evince that this area can be divided into 3 categories according to hourly ozone concentration in summer. Cluster 1 is comprised of monitoring stations located in the outskirts of the city of Seville; Cluster 2 corresponds to monitoring stations located within the city of Seville; and Cluster 3 is comprised of a monitoring station specialized in traffic emissions. Multiple linear regression shows that the relative weight of meteorological variables decreases when moving from the urban periphery towards the urban center, whereas the weight of chemical variables increases. Coefficients of determination (R2) values were 0.885, 0.890 and 0.830 and root mean squared error (RMSE) were 11.226, 11.874 and 11.260 μg m−3 for Cluster 1, 2 and 3, respectively.

Fast and Optimized Methodology to Generate Road Traffic Emission Inventories and Their Uncertainties

Road traffic emissions are one of the main sources of air pollution in urban areas and also main sources of uncertainties in air quality numerical models. Until now, the available models for generating road traffic emission always required a lot of money, manpower and time. This inhibits decisions to preserve air quality, especially in developing countries where road traffic emissions are changing very fast. In this research, we developed a new model designed to quickly produce road traffic emissions. This model, called EMISENS, combines the well‐known top‐down and bottom‐up approaches to force them to be coherent. A Monte Carlo methodology is included for computing uncertainties. This paper presents the EMISENS model and a demonstration of its capabilities through an application over Strasbourg, France. Same input data as collected for Circul'air model using bottom‐up approach which has been applied for many years to forecast and study air pollution by the Alsatian air quality agency, are used to evaluate the impact of several simplifications. These experiments give the possibility to review older methodologies and evaluate EMISENS. We show that same average fraction of mileage driven with a cold engine can be used for all the cells of the study domain and one emission factor could replace both cold and hot emission factors.

Overview of the impact of wood burning emissions on carbonaceous aerosols and PM in large parts of the Alpine region

During the past years, actions implemented for the reduction of particulate matter emissions have in many European countries focused on road traffic emissions. Much less attention was paid to emissions from domestic wood combustion though the importance of residential wood burning as a source of atmospheric particulate matter (PM) in the Alpine region has been shown in many studies.Here we review the current knowledge about the contribution of wood burning emissions to ambient concentrations of elemental carbon (EC), organic carbon (OC) and PM in the Alpine region. The published results obtained by different approaches (e.g. macro-tracer method, multivariate receptor modeling, chemical mass balance modelling, and so-called Aethalometer modeling) are used in an ambient mono-tracer approach to estimate representative relationships between wood burning tracers (levoglucosan and mannosan) and EC, OC and PM from wood burning. The relationships found are applied to available ambient measurements of levoglucosan and mannosan at Alpine sites for estimation of the contributions of wood burning emissions to average levels of carbonaceous aerosols and PM at these sites. Our results imply that PM from wood burning alone adds often up to 50% and more of the EU daily limit value for PM10 in several alpine valleys during days in winter. Concentrations of carbonaceous aerosols in these valleys are often up to six times higher than in urban or rural sites at the foothills of the Alps.

Biogenic and anthropogenic isoprene in the near-surface urban atmosphere — A case study in Essen, Germany

Isoprene is emitted in large quantities by vegetation, exhaled by human beings and released in small quantities by road traffic. As a result of its high reactivity, isoprene is an important ozone precursor in the troposphere and can play a key role in atmospheric chemistry. Measurements of isoprene in urban areas in Central Europe are scarce. Thus, in Essen, Germany, the isoprene concentration was measured at various sites during different seasons using two compact online GC-PID systems. Isoprene concentrations were compared with those of benzene and toluene, which represent typical anthropogenic VOCs. In the summer, the diurnal variation in isoprene concentration was dependent on the biogenic emissions in the city. It was found that its maximum concentration occurred during the day, in contrast to the benzene and toluene concentrations. During the measurement period in the summer of 2012, the average hourly isoprene concentrations reached 0.13 to 0.17ppb between 10 and 20 LST. At high air temperatures, the isoprene concentration exceeded the benzene and toluene concentrations at many of the sites. Isoprene became more important than toluene with regard to ozone formation in the city area during the afternoon hours of summer days with high air temperatures. This finding was demonstrated by the contributions to OH reactivity and ozone-forming potential. It contradicts the results of other studies, which were based on daily or seasonal average values. With an isoprene/benzene ratio of 0.02, the contribution of anthropogenic isoprene decreased substantially to a very low level during the last 20years in Central Europe due to a strong reduction in road traffic emissions. In the vicinity of many people, isoprene concentrations of up to 0.54ppb and isoprene/benzene ratios of up to 1.34 were found in the atmosphere due to isoprene exhaled by humans.

Modelling of air pollution in the area of Algiers City, Algeria

Algiers is the political and economic capital of Algeria. The city drains a large part of the activities of the country with intense road traffic. This road traffic is the main source of air pollution, followed by industry and waste combustion. An application of the new road traffic emission model, called EMISENS, is performed to build road traffic emission inventories for the Algiers region. These emission inventories are then used as input to the MM5/CHIMERE system to estimate air pollution. The objective of this study is to propose a methodology to improve the quality of emission inventories, and to validate results. First, by studying the correlation between observed measurements and data concerning cadastre of primary pollutants emitted mainly by road traffic, then by comparing the pollutants concentrations from observed measures with the simulated concentrations with the model of chemistry-transport CHIMERE.

Size fractionated aerosol composition at roadside and background environments in the Madrid urban atmosphere

The chemical composition of size-segregated particulate matter (PM) was studied during summer and winter sampling campaigns, at two different urban sites (roadside and urban background) in the city of Madrid, Spain. PM was sampled with high volume cascade impactors, in 4 size ranges: 10–2.5, 2.5–1, 1–0.5 and <0.5μm. The carbonaceous content (OC and EC) was determined by a thermo-optical method, whilst the water soluble ionic species were measured by ion chromatography. The most common synoptic meteorological situations, including those causing the transport of African dusty air masses, were identified in both seasons. Whether the PM10 mass or the highest concentrations of EC and OC were found predominantly in the ultrafine size fraction at both sites. In contrast with roadside, at the urban background, the particle mass concentrations for the different size ranges were statistically higher in summer than in winter. Observed inter-site differences suggest the existence of other sources and formation processes contributing in the summer period to the levels of PM at the urban background site apart from road traffic emissions. Secondary organic carbon (SOC) showed a clear seasonal pattern, with much higher concentrations in summer than in winter in both places, as well as higher relative contributions at the urban background than at the road traffic site. (NH4)2SO4 levels were at their maximum at both sites in summer in PM0.5. Differently, higher values were reached in winter for NH4NO3 in PM0.5 and for NaCl in PM2.5–10. From the ion balances, it was observed that, in summer, the formation of secondary inorganic compounds included an unusual enrichment in Ca2+ in the submicrometre fraction, either at roadside or at urban background.

Assessment of potential improvements on regional air quality modelling related with implementation of a detailed methodology for traffic emission estimation

The accuracy and precision of air quality models are usually associated with the emission inventories. Thus, in order to assess if there are any improvements on air quality regional simulations using detailed methodology of road traffic emission estimation, a regional air quality modelling system was applied. For this purpose, a combination of top-down and bottom-up approaches was used to build an emission inventory. To estimate the road traffic emissions, the bottom-up approach was applied using an instantaneous emission model (Vehicle Specific Power — VSP methodology), and an average emission model (CORINAIR methodology), while for the remaining activity sectors the top-down approach was used. Weather Research and Forecasting (WRF) and Comprehensive Air quality (CAMx) models were selected to assess two emission scenarios: (i) scenario 1, which includes the emissions from the top-down approach; and (ii) scenario 2, which includes the emissions resulting from integration of top-down and bottom-up approaches. The results show higher emission values for PM10, NOx and HC, for scenario 1, and an inverse behaviour to CO. The highest differences between these scenarios were observed for PM10 and HC, about 55% and 75% higher (respectively for each pollutant) than emissions provided by scenario 2. This scenario gives better results for PM10, CO and O3. For NO2 concentrations better results were obtained with scenario 1. Thus, the results obtained suggest that with the combination of the top-down and bottom-up approaches to emission estimation several improvements in the air quality results can be achieved, mainly for PM10, CO and O3.

PM2.5 concentrations in London for 2008–A modeling analysis of contributions from road traffic

We report on the analysis of contributions from road traffic emissions to fine particulate matter (PM2.5) concentrations within London for 2008 with the OSCAR Air Quality Assessment System. A spatiotemporal evaluation of the OSCAR system has been conducted with measurements from the London air quality network (LAQN). For the predicted and measured hourly time series of concentrations at 18 sites in London, the medians of correlation, mean absolute error, index of agreement, and factor of two (FAC2) of all stations were 0.80, 4.1 μg/m3, 0.86, and 74%, respectively. Spatial evaluation of modeled and observed annual mean concentrations also showed a fairly good agreement, with all the values falling within the FAC2 range. According to model predictions, the urban increment (including the contributions from urban traffic and other urban sources) was evaluated to be on the average 18%, 33%, 39%, and 43% of the total PM2.5 in suburban environments, in the urban background, near roads, and near busy roads, respectively. However, the highest values of the urban traffic increment can be around 50% of the total PM2.5 concentrations near motorways and major roads. The total concentrations (including regional background, and the contributions from urban traffic and other urban sources) can therefore be almost three times the regional background. The total urban increment close to busy roads was around 7–8 μg/m3, in which the estimated traffic contribution is more than 2 μg/m3. On the average, urban traffic contributes approximately 1 μg/m3 of PM2.5 to the urban background across London. According to modeling, approximately two-thirds of the traffic increment originated from exhaust emissions and most of the rest was due to brake and tire wear.Implications: The urban increment and traffic contribution to the total PM2.5 are significant and spatially heterogeneous across London. The highly heterogeneous distribution of PM2.5 hence requires detailed modeling studies to be carried out at high spatial resolution, which can be particularly important for exposure and health impact assessment. This type of information can be used to quantify health impacts resulting from specific sources of PM2.5 such as traffic emissions, to aid city and national decision makers when formulating pollution control strategies.

Accumulation of polycyclic aromatic hydrocarbons (PAHs) on the spider webs in the vicinity of road traffic emissions

Studies focused on the possible use of spider webs as environmental pollution indicators. This was a first time ever attempt to use webs as indicators of polycyclic aromatic hydrocarbons (PAHs) pollution. The aim of the study was (a) to evaluate whether webs are able to accumulate PM-associated road traffic emissions and be analyzed for organic toxics such as PAHs, (b) to assess if the distance from emission sources could have an influence on the accumulation level of pollutants, and (c) to determine types of pollution sources responsible for a structure of monitoring data set. Webs of four species from the family Agelenidae were sampled for PAHs presence. Data from vehicle traffic sites (i.e., road tunnel, arterial surface road, underground parking) and from railway traffic sites (i.e., two railway viaducts) in the city of Wroclaw (Southwest of Poland) showed a significantly higher mean concentrations of PAHs than the reference site 1 (municipal water supply works). We also found a significant differences at sites differed by the distance from emission sources. The result of PCA analysis suggested three important sources of pollution. We conclude that spider webs despite of some limitations proved useful indicators of road traffic emissions; they could be even more reliable compared to use of bioindicators whose activity is often limited by a lack of water and sun.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-013-2092-0) contains supplementary material, which is available to authorized users.

Health effects of black carbon in the city of Barcelona

Background. Current air quality standards for particulate matter (PM) use the mass concentration of PM with aerodynamic diameters ?2.5 ?m (PM2.5) and ?10 ?m (PM10) as metric. It has been suggested that particles from combustion sources are more relevant to human health than particles from other sources. However, only few studies have assessed for adverse health effects of black carbon (BC) as an additional in air quality indicator in Europe. Aim. To investigate the short-term effects of BC on total daily mortality, in the city of Barcelona (Spain). Methods. We collected daily burials due to natural causes, as indicator of total daily mortality, and daily 24h average levels of BC, PM2.5 and PM10 between 2009 and 2012. We used a time-stratified case-crossover design with Poisson regression allowing for overdispersion. BC estimates are compared with those obtained with the usual indicators of PM mass. Results. Estimated health effects of an interquartile range increase were greater for BC than for PM2.5 and PM10. An increase of 1.4 ?g/m3 in BC increased mortality by 3%, while an increase of 10.5 ?g/m3 in PM2.5, and of 17.0 ?g/m3 of PM10, increased mortality by &lt;1%. Two-pollutant models showed that effect of the BC was more robust than effect of the PM mass. Conclusions. BC is a valuable additional air quality indicator to evaluate the health risks of air quality dominated by primary combustion particles, , in our case by road traffic emissions.

Adopting Black Carbon/Elemental Carbon as a Tool in Mobility Planning: the General Urban Traffic Plan of the City of Milan, Italy

Background. As part of the Strategic Environmental Assessment (SEA) procedure of the General Urban Traffic Plan, the Municipality of Milan introduced Elemental Carbon - basing on the experience with the air quality measurement of Black Carbon within the city - among quantitative indicators. Aims. To obtain a particulate toxicity indicator, easy-to-use within the normal planning activities of a local Public Authority, estimating environmental and health potential effects of different policy scenarios. Methods. Being the carbonaceous nanoparticles such as Black Carbon (BC), a sensitive indicator of the spatial variation of road traffic emissions (‘traffic proximity’ indicator), the emissions of Elemental Carbon (EC), pollutant closely related to BC, have been adopted as tracers of the population exposure. According to the literature, a critical distance from the vehicular traffic source has been identified to which refer evaluations of some health effects that have 'sufficient evidence' (in. asthma). People living at a distance &lt;75 m from major roads have an increased probability by about 30% of receiving a diagnosis of asthma and by about 40%-50% to be on medication for asthma or have had recent acute episodes in children (McConnell et al, 2006; Perez, 2012; Brugge et al, 2007). Thus an exposure indicator has been defined as the daily mean vehicular EC emissions released at a distance less than 75 meters from places of residence. This indicator has been estimated for several mobility planning scenarios. Results. This approach has proven to allow easy scenario comparison analysis. In the city of Milan, road pricing scenario at 2015 leads to an increase of total population exposed to lower emission levels (&lt;10 grams/day) and to a decrease of total population exposed to highest emission levels (&gt;50 grams/day). Conclusions. BC/EC, excellent tracer of 'traffic proximity‘ exposure, offers the possibility to verify the effectiveness of different policies in mobility planning.

Transplantation of epiphytic bioaccumulators (Tillandsia capillaris) for high spatial resolution biomonitoring of trace elements and point sources deconvolution in a complex mining/smelting urban context

Monitoring atmospheric trace elements (TE) levels and tracing their source origin is essential for exposure assessment and human health studies. Epiphytic Tillandsia capillaris plants were used as bioaccumulator of TE in a complex polymetallic mining/smelting urban context (Oruro, Bolivia). Specimens collected from a pristine reference site were transplanted at a high spatial resolution (∼1 sample/km2) throughout the urban area. About twenty-seven elements were measured after a 4-month exposure, also providing new information values for reference material BCR482. Statistical power analysis for this biomonitoring mapping approach against classical aerosols surveys performed on the same site showed the better aptitude of T. Capillaris to detect geographical trend, and to deconvolute multiple contamination sources using geostatistical principal component analysis. Transplanted specimens in the vicinity of the mining and smelting areas were characterized by extreme TE accumulation (Sn > Ag > Sb > Pb > Cd > As > W > Cu > Zn). Three contamination sources were identified: mining (Ag, Pb, Sb), smelting (As, Sn) and road traffic (Zn) emissions, confirming results of previous aerosol survey.