Side Of Highway Research Articles

The impact of vegetative and solid roadway barriers on particulate matter concentration in urban settings.

A potentially important approach for reducing exposure to traffic-related air pollution (TRAP) is the use of roadside barriers to reduce dispersion from highway sources to adjacent populated areas. The Trees Reducing Environmental Exposures (TREE) study investigated the effect of vegetative and solid barriers along major controlled-access highways in Atlanta, Georgia, USA by simultaneously sampling TRAP concentration at roadside locations in front of barriers and at comparison locations down-range. We measured black carbon (BC) mass concentration, particle number concentration (PNC), and the size distribution of ultrafine aerosols. Our sample sites encompassed the range of roadway barrier options in the Atlanta area: simple chain-link fences, solid barriers, and vegetative barriers. We used Generalized Linear Mixed Models (GLMMs) to estimate the effect of barrier type on the ratio of particle concentrations at the comparison site relative to the roadside site while controlling for covariates including wind direction, temperature, relative humidity, traffic volume, and distance to the roadway. Vegetative barriers exhibited the greatest TRAP reduction in terms of BC mass concentration (37% lower behind a vegetative barrier) as well as PNC (6.7% lower), and sensitivity analysis was consistent with this effect being more pronounced when the barrier was downwind of the highway. The ultrafine size distribution was comprised of modestly smaller particles on the highway side of the barrier. Non-highway particle sources were present at all sample sites, most commonly motor vehicle emissions from nearby arterials or secondary streets, which may have obscured the effect of roadside barriers.

The heavy metals content in leaves and branch of Hippophae rhamnoides L. and Pyrus elaeagnifolia Pall. in the highway side (European route E80) in Türkiye

The heavy metals content in leaves and branch of Hippophae rhamnoides L. and Pyrus elaeagnifolia Pall. in the highway side (European route E80) in Türkiye

Metal composition and contamination assessment of urban roadway dusts on the Abu Dhabi-Liwa Highway, UAE

The metal composition of road-deposited dust along the Abu Dhabi-Liwa Highway was investigated to provide insight into the contamination profile and levels of road dust. The average concentrations of metals decreased in the order Al (28668 ± 4631 mg/kg)> Fe (21461 ± 2594 mg/kg) > Mn (711.8 ± 76.3 mg/kg) > Zn (210.6 ± 51.6 mg/kg) > Cu (94.9 ± 15.8 mg/kg) > Pb (83.6 ± 5.3 mg/kg) > Cd (75.1 ± 1.6 mg/kg) > Co (62.6 ± 6.4 mg/kg) > As (4.7 ± 2.9 mg/kg) > Ni (0.10 ± 0.19 mg/kg) > Cr (0.08 ± 0.06 mg/kg). The spatial variations of metals suggest different sources and contributing factors for these metals, with most dust metals having mixed traffic and non-traffic origins. The contamination factor (CF) and enrichment factor (EF) showed identically the same order, Cd> Pb> As> Zn> Co> Cu> Mn> Ni> Cr, whereas the geoaccumulation index (Igeo) follows a slightly different ranking, Cd> Pb> Zn> Co> As> Cu> Mn> Ni> Cr. Based on EF and CF levels, roadway dusts are enriched in all metals, except for Ni and Cr. Similarly, the average Igeo values show differing rates of pollution for all metals except for Mn, Ni, and Cr. All pollution indicators suggest extreme pollution with Cd. The pollution loading index values showed sites 1–10 are generally polluted, while sampling sites from 11 to 19 are unpolluted with decreasing pollution loadings. Dusts collected from both sides of highway were higher in metal content than those obtained from the central reservation area. This may be due to the prevailing southeast wind direction, resuspension of road dust, and farmlands, among others. Soils bordering the highway showed high metal contents with potential consequences on the agricultural products.

Anthropogenic Contribution and Migration of Soil Heavy Metals in the Vicinity of Typical Highways

To reveal the secondary anthropogenic contribution and accumulation rate of heavy metals in highway-side soils, we studied soil heavy metals on three representative highways in Southeast China, with different traffic intensities, service years, land use patterns and distances from roads, with high-resolution sampling of soil profiles. Concentrations of soil Cu, Zn, Pb and Cd were measured. The comparison of concentrations in surface soils with original values and their vertical distributions shows that soils within 150 m of the highway side are contaminated by heavy metals, with surface accumulation and possible movement down the profiles. The transferring depth of heavy metals was 10–30 cm. The contribution ratios of heavy metals were 1.0–30.5% in the surface at 30 cm, with the sequence of Cd >> Cu > Zn > Pb. The accumulation rates were 1.27–2.03 kg Cu ha−1 y−1, 2.44–5.27 kg Zn ha−1 y−1, 0.71–1.40 kg Pb ha−1 y−1 and 0.010–0.018 kg Cd ha−1 y−1 in soils within 50 m range. Furthermore, the accumulation of these metals varied with the traffic intensity, service years and land use patterns. Soils under forest have less heavy metal accumulation, which suggests a protective forest to set beside highways at a distance of at least 50 m to prevent soils from being contaminated.

Evaluation of HMF levels in unbranded flower honeys in terms of food safety

5-hydroxymethylfurfural (HMF) is formed by reducing sugars in honey in acidic environments by the Maillard reaction and is known as a carcinogenic, mutagenic and genotoxic compound. The aim of this study is to investigate the toxic HMF content of unbranded flower honey samples sold under the sun under inappropriate conditions and unsupervised on the highway sides and to make an evaluation in terms of food safety. The quality of the analysis results was guaranteed by participating in an international proficiency test. Analysis was performed on a High-Performance Liquid Chromatography (HPLC) device with Diode Array Detector (DAD) and Refractive Index (RI) detectors- The HMF levels of 5 honey samples were determined to exceed the legal limit (40 mg kg-1). It is revealed by the current study that the honey sold on the roadside is not safe in terms of toxic HMF. In addition, 5 samples were not found to comply with the regulation in terms of glucose + fructose content and 2 samples in terms of fructose/glucose ratio. Thus, it has also been determined that these honeys are not reliable in terms of purity.

Biomonitoring and phytoremediation potential of the leaves, bark, and branch bark of street trees for heavy metal pollution in urban areas.

Tree tissues can accumulate heavy metals from the environment. We therefore aimed to evaluate the presence of the metals Pb, Cr, Mn, Cu, and Zn in four street tree species, namely Ailanthus altissima, Broussonetia papyrifera, Pinus tabuliformis, and Rhus typhina, along the highway side of Beijing, China. Sampling from the leaves, trunk bark, and branch annual segment bark of trees was conducted in the summer of 2021, and the concentration of heavy metals was determined. The results revealed the highest average concentration of total heavy metals in the R. typhina leaves (23.724 mg/kg) and barks (14.454 mg/kg). The maximum bio-concentration factor was noted for Zn in the B. papyrifera leaves (0.36) and P. tabuliformis barks (0.21). The maximum comprehensive bio-concentration index was observed for the B. papyrifera leaves (0.225) and P. tabuliformis bark (0.108). The maximum metal accumulation index was measured in the R. typhina leaves (29.682) and bark (12.407). Based on the air-originated metals, P. tabuliformis showed the highest dust collection capacity. In general, B. papyrifera and P. tabuliformis exhibited the highest absorption rate from the soil relative to the other studied species. R. typhina demonstrated the strongest phytoremediation ability for heavy metal pollution in air. In addition, our results proved that the branch annual segment bark of P. tabuliformis is an excellent record carrier that can be used to monitor heavy metal pollution in a specific time duration in an urban area.

Bound to the Land: Cove Fort in Kesler Family History and Memory

Bound to the Land: Cove Fort in Kesler Family History and Memory

Causes and control to lateral displacement of the main girder in the super-long-span cable-stayed bridge with transverse asymmetry dead load

In the densely populated large cities, to save valuable land resources and fit the plane alignment of the approach bridge at two ends of the main bridge, the long-span Rail-cum-Road cable-stayed bridge is arranged on the same deck with the lateral asymmetric layout. This makes the transverse secondary dead load of the main girder asymmetric and the mechanical characteristics different from the conventional cable-stayed bridge. In this paper, firstly, several measures to realize the ideal vertical alignment of the main girder for such cable-stayed bridges were analyzed theoretically, and the mechanical characteristics of the main girder via the measure of asymmetrical cable force were mainly explored. Then, taking the Changzhou-Taixing Yangtze River bridge as a typical example, a simplified mechanical model was proposed to calculate the lateral displacement of the main girder and was compared with the finite element model (FEM) of the whole bridge. Finally, according to the mechanical model, the control measures to lateral displacement of the main girder were discussed. The results show that the unbalanced longitudinal and lateral components corresponding to the asymmetric cable force lead to the main girder to deviate railway side and the highway side, respectively, and the corresponding variance value of lateral displacement is not significant, which greatly reduces the lateral shift effect of the main girder. Furthermore, the simplified mechanical model can effectively calculate the lateral displacement of the main girder and study the control measures for displacement. The conclusions of this study can provide a basis for further design of the same type of bridge.

Performance Assessment of Crash Barriers used in Road Safety: A Case Study of Malekhu Kurintar Section of the Prithvi Highway

Hill roads in Nepal are comprised of critical geometry and limited roadway clearances. It causes high number of runoff roadway type of accidents with single vehicle. These accidents often carry huge number of fatalities and severe injuries. Installation of crash barriers is the most effective way of preventing such accidents along hill roads. However, the existing practice of construction of crash barriers does not show the satisfactory results. Therefore, this research aimed at the evaluation of typical crash barriers constructed along the valley side of highway. Analysis of the road accident of Malekhu-Kurintar section of Prithvi Highway record shows that this section has relatively higher accident rate and most of the accidents are runoff roadway type. Further, these accidents are mainly caused due to either the absence or the failure of the crash barriers along the valley side of the highway. On the basis of field records, kinetic energy absorbed by the crash barriers and their deflections was investigated by application of computer based analysis tool ABAQUS V6.10. It has given satisfactory results on the deflection of W-beam and plum concrete barriers due to the impact of vehicle moving in various range of speed.

New outcrop with vertebrate remains from Solimões Formation (Eocene–Pliocene), Southern Solimões Basin, Acre State, Northern Brazil

Here we describe fossil vertebrate remains from a new Solimões Formation (Eocene-Pliocene) locality, near the highway BR 364 at Sena Madureira municipality (Acre, Brazil). The findings comprise more than forty-four isolated fragments from which twenty-three specimens could be properly identified anatomically and systematically. The materials include at least three different Caimaninae genera (Caiman, Melanosuchus, and Mourasuchus), two distinct side-necked turtles (Chelus and Podocnemididae) and one mammal (Toxodontidae). The studied fossils could be systematized into two taphonomic classes based on their preservational status, indicating a sinuous fluvial meandering paleoenvironment. This new locality seems to be relevant regarding not only its fossil vertebrate diversity but also because of its geographic position: on a highway side, which allows access at any season of the year, as contrary to most common riverine outcrops from Solimões Formation, which are restricted to collections during the dry seasons.

Short Report on an Intensive Archeological Survey for the Schertz-Seguin Local Government Corporation’s Proposed SH123/Austin Street Water Line Installation Project, Guadalupe County, Texas

Schertz-Seguin Local Government Corporation (Client) is proposing to construct an 18-inch water main pipeline along the west side of State Highway (SH) Business 123 (Stockdale Highway/South Austin Street) crossing of the Guadalupe River in the City of Seguin, Guadalupe County, Texas (Project). According to current design plans, the proposed water line would be connected to an existing pipeline located approximately 75 feet (ft) [23 meters (m)] north of the Guadalupe River near the existing Max Starke Park Water Treatment Plant and an existing main pipeline located approximately 75 ft (23 m) south of the Guadalupe River along SH 123 in Seguin, Texas. The Area of Potential Effects (APE) consists of two work areas, one north and one south of the Guadalupe River. The northern work area consists of 0.20 acres (ac) and the southern work area consists of 0.15 ac. The APE is 0.35 ac in total. The Project is within the City of Seguin, a subdivision of the state , and thus triggers a review of cultural resources under the Antiquities Code of Texas (Section 191.0525). Additionally, due to Army Corps of Engineers (USACE) permitting requirements the Project falls under the regulations of Section 106 of the National Historic Preservation Act of 1966, as amended (U.S. Code 16, §470, et seq.). TRC archeologists conducted a limited desktop literature and archives review for the proposed Project to assess whether previously recorded cultural resources are within or adjacent to the APE or within a 1-mile (mi) (1.6-kilometer [km]) of the APE. This included a review of the THC’s Archeological and Historic Sites Atlas (Atlas) which provides information related to the location of previously conducted archeological surveys and recorded archeological sites, cemeteries, properties currently listed or eligible for listing on the National Register of Historic Places (NRHP), Recorded Texas Historic Landmarks (RTHLs), and State Antiquities Landmarks (SALs) that may be impacted by the proposed Project. According to the THC-Atlas, no previously conducted archeological surveys, archeological sites, cemeteries, historic properties, or historical markers intersect or are adjacent to the APE. Fieldwork was conducted by TRC archeologists on February 12, 2020 under Antiquities Permit Number 9263. The intensive archeological field survey included survey of 100 percent of the APE supplemented with shovel testing and visual inspection. Survey methods followed the guidelines and survey standards set forth by the THC and Council of Texas Archeologists (CTA). Review of the project plans showed that of the 155 m (509 ft) proposed water line only 27 m (89 ft) of the line to the north and 18 m (59 ft) of the line to the south will be buried with the remainder above ground and spanning the Austin Street bridge. Survey efforts were concentrated along the buried portions of the proposed water line. Due to the high degree of ground disturbance from existing utilities, bridge construction, and the presence of steep slope only a single shovel test could be excavated. Nine additional ‘No Dig’ observation points were recorded to document the areas of disturbance and slope. No cultural resources or historic structures were identified within the APE. No additional work is recommended.

Stability Analysis of Slopes on Both Sides of Highway in Geotechnical Area under Rainfall Conditions

The objective of this study is to correctly analyze the slope stability, strengthen the guidance of engineering construction, and ensure the safety of people’s lives and property. In this study, the numerical simulation software Geo-Studio is used to simulate the stability variation rules of the slope on both sides of the highway in the rocky region when the angles of the upper and lower slope of the platform width are changed under the action of light rain for a long time respectively, and the corresponding comparison analysis is made with the corresponding natural working condition. The results show that the infiltration of rainwater has a great influence on the slope on both sides of the highway in the geotechnical area, which is mainly reflected in the decrease of the stability of the multi-level slope, the significant change of the sliding surface (including the location, size, shape, etc. of the sliding surface), the potential instability form of the slope (overall stability and local stability), and the slow but continuous change of the pore water pressure in the soil. Through the rainfall test on the highway slope, it is found that the instability mechanism of the slopes on both sides of the highway in the geotechnical area is affected by the conditions of rainfall intensity, rainfall duration, cumulative rainfall capacity, and rainfall patterns. In addition, the changes of rainfall infiltration rate in the side slope of highway in rock and soil area and the migration rules of water field in side slope are also obtained. The findings of this study can be used as a reference and basis for engineering design and construction. Moreover, the safety coefficient of the slope after renovation meets the stability requirement. Therefore, the slope engineering treatment measures on both sides of the highway can effectively deal with the hidden disaster brought by landslide deformation or instability.

A Framework for Green Concrete Noise Barrier Materials using Palm Oil Clinker

Noise pollution from traffic is an increasing environmental problem worldwide. The most popular mitigation measure is the control of path by means of construction of noise barriers. Current concrete barrier incorporated with perforated surface infilled with non-mineral fibre sound absorbing material on the highway side are the commonly found. The disadvantage of this type is it’s easily damaged and the non-mineral fibre is so dreadful to human health. On the other hand, palm oil clinker (POC) is a by-product waste material produced in palm oil mills, are currently dump in open land or landfill sites, which leads to environmental problems. POC is internally porous and if it replaces the aggregate in porous concrete it may absorb sound better than standard porous concrete which is the most important characteristic for noise barrier development. This paper discusses how the palm oil clinker substitution will make concrete noise barrier material to be labelled as green and sustainable. A framework for developing green noise barrier made of palm oil clinker concrete will also be presented and discussed.

Key Design Indicators for Roadside Warning Piles

This study aims to investigate retroreflectivity sheeting matching and design of highway warning piles. The effects of relevant parameters on the nocturnal guidance for a change in horizontal alignment of highway-side warning pile are studied and discussed by using real vehicle tests. We consider the two forms of warning piles that are commonly used on national highways. The first is the red and white warning piles, which is used for warning function of access spots; and the second is the yellow and black warning piles, which is used for the induction function of highway side profile. Deceleration spots before the vehicle enters the bend and the smoothness of the deceleration process are considered identification indicators on the basis of the real vehicle test. We obtain optimal quantities of retroreflectivity sheeting matching and design of highway warning piles using mathematical statistics method and correlation analysis. We also propose a corresponding low-cost solution considering the low budget of low-class highways.

Assessment of Pinus sylvestris L. tree health in urban forests at highway sides in Lithuania

Trees are often grown alongside roads in urban areas for their aesthetic and ecological values but are exposed to an array of natural and man-made stresses that impact on their overall health. The aim of this study was to determine the health of Scots pine (Pinus sylvestris L.) trees growing in urban forests alongside the Vilnius–Kaunas–Klaipėda highway in Lithuania. Long-term monitoring was conducted between 1998 and 2014, when health indicators were evaluated in 714 trees at different distances from the highway. The decrease of crown defoliation, amount of dead branches and foliage discolouration at all distances from the roadbed was detected. The results showed that trees furthest (450–500 m) from the roadbed were in better health than those growing close to the highway, exhibiting lowest crown defoliation (25.8 ± 1.6% in 1998, 12.3 ± 1.6% in 2014) compared with trees growing close to highway (47.2 ± 1.6% in 1998; 25.1 ± 1.7% in 2014), lowest foliage discolouration (14.8 ± 1.2% in 1998, 9.8 ± 0.8% in 2014), a lower amount of dead branches (14.8% ± 1.2% in 1998, 9.8% ± 0.8% in 2014) and a longer needle retention (3.2 ± 0.03 years in 2014 comparing with to 1.9 ± 0.02 close to the highway). The condition of the tree tops was good throughout the study period, with 77% of assessed trees being healthy. Statistically significant improvement in tree health was observed between 1998 and 2014, indicating an improvement in the overall health of the environment.

Spatial Distribution and Risk Assessment of Heavy Metals in Paddy Soils of Yongshuyu Irrigation Area from Songhua River Basin, Northeast China

There is an increasing concern for potentially hazardous metals pollution, which can threaten crops production and human health. In this study, the spatial distribution and environmental risks of eight heavy metals in surface soil samples collected from the paddy fields in Yongshuyu irrigation area, Northeast China were investigated. The mean concentrations of Pb, Cr, Cu, Ni, Zn, Cd, Hg and As were 34.6 ± 4.67, 82.8 ± 9.51, 17.3 ± 4.09, 21.2 ± 12.0, 88.6 ± 17.9, 0.18 ± 0.15, 0.22 ± 0.07 and 8.77 ± 2.47 mg/kg, respectively, which were slightly higher than their corresponding background values of Jilin Province, indicating enrichment of these metals in the paddy soils, especially for Ni, Cd and Hg. The spatial distribution of heavy metals was closely correlated with local anthropogenic activities, such as agricultural production, mining and transportation. The hot-spot areas of As and Cd were mainly concentrated in the up-midstream where were associated with agricultural activities. Cr and Cu showed similar spatial distributions with hot-spot areas distributed the whole irrigation area uniformly. Ni was mainly distributed in the downstream where Ni quarries concentrated, while the spatial distribution patterns of Hg was mainly located in the upstream and downstream where the soil was significantly influenced by irrigation and coal mining emission. The spatial distributions of Pb and Zn were mainly concentrated along the highway side. The pollution levels of Yongshuyu irrigation area were estimated through index of geo-accumulation (Igeo), Nemerow integrated pollution index (NIPI) and potential ecological risk index (PERI). The results showed that Cd and Hg were the main pollutants in the study area. Health risk assessment results indicated that children were in higher non-carcinogenic and carcinogenic risks than adults with the carcinogenic metal of As. Ingestion was the main exposure pathway to non-carcinogenic and carcinogenic risk for both adults and children. Principal component analysis (PCA) indicated that Cr and Cu were mainly from parent materials, while Cd and As were mainly affected by agricultural activities. Pb and Zn were controlled by traffic activities, and the accumulations of Ni and Hg were associated with mining activities. This study would be valuable for preventing heavy metals inputs and safety in rice production of the Songhua river basin.

Spacing and geometric design indexes of auxiliary lanes on two-lane highway in China

Auxiliary lanes on two-lane highway are lanes setting on the right side of highway for the slow vehicles, and they can provide safe overtaking chances for cars using the original lane instead of the opposite lane. Based on the principle that the net benefit is greater than zero, the calculation model of the minimum spacing of auxiliary lanes on two-lane highway is established. After calibrating the model parameters, recommended minimum spacing values for auxiliary lanes are given corresponding to different highway classes, design speeds, and terrains. Based on traffic simulation data, the relationship model is established among the length of auxiliary lane section with uniform widths, traffic volumes, and driving speeds. By analyzing the design capacity of two-lane highway, suggestion values of the length of auxiliary lane section with uniform widths are given for two-lane highway with different design speeds and terrains. Based on driving safety and questionnaire survey on lateral vehicle spaces, calculation formula and suggestion values are presented for the width of auxiliary lanes on two-lane highway.

A single migrant enhances the genetic diversity of an inbred puma population.

Migration is essential for maintaining genetic diversity among populations, and pumas (Puma concolor) provide an excellent model for studying the genetic impacts of migrants on populations isolated by increasing human development. In densely populated southern California, USA, puma populations on the east and west side of interstate highway 15 (I-15) have become fragmented into a small inbred population on the west side (Santa Ana Mountains) and a relatively larger, more diverse population on the east side (Eastern Peninsular Range). From 146 sampled pumas, genetic analyses indicate seven pumas crossed I-15 over the last 15 years, including four males from west to east, and three males from east to west. However, only a single migrant (named M86) was detected to have produced offspring and contribute to gene flow across the I-15 barrier. Prior to the M86 migration, the Santa Ana population exhibited inbreeding and had significantly lower genetic diversity than the Eastern Peninsular Range population. After M86 emigrated, he sired 11 offspring with Santa Ana females, decreasing inbreeding measures and raising heterozygosity to levels similar to pumas in the Eastern Peninsular Range. The emigration of M86 also introduced new alleles into the Santa Ana population, although allelic richness still remained significantly lower than the Eastern Peninsular population. Our results clearly show the benefit of a single migrant to the genetics of a small, isolated population. However, ongoing development and habitat loss on both sides of I-15 will increasingly strengthen the barrier to successful migration. Further monitoring, and potential human intervention, including minimizing development effects on connectivity, adding or improving freeway crossing structures, or animal translocation, may be needed to ensure adequate gene flow and long-term persistence of the Santa Ana puma population.

Soil Investigation at Wet World Hot Spring Complex for Future Development using Active Multichannel Analysis of Surface Waves

Development of hot spring touristic projects receives more interest in Malaysia in recent years since the country has a high potential of hot springs that are vital to the economy. However, such developmental activities could produce negative impacts if not accompanied with adequate knowledge of the subsurface conditions. Active multichannel analysis of surface waves (MASW) was applied to determine the subsurface shear wave velocities and Vs30. The inverted shear waves velocity models have then presented in both vertical cross-sectional plots and depth slices maps. Depth slices were chosen at about 5, 18.5 m and 32 m depths. Model obtained showed that the soil is stiffer near the highway side and turns to be softer as we go away in the scrub direction. Vs30 is also estimated and mapped to show the quality of the soil. Inverted parameters showed that the soil at the site ranges from soft soil to stiff one. Also, the result obtained proposed that the surface occurrence of the hot spring might be a result of intersection of faulted segments, where hot spring is located near the intersection points. Furthermore, the model helped in proposing a suitable for complex extension. The proposed is chosen such that it minimize any possible effects on the geothermal resources at the site.

Prevention of Noise Pollution caused by Highways in Settlement Areas via a Noise Insulation System

The noise, which is taken as unimportant at first glance, had become one of the most important factors, causing pollution of environment, because of civilization. Together with the industrial development, mechanization in work places, increase in the number of highways, increased traffic load had made the noise an important problem in pollution and prevention of environment. In this project prevention of the noise caused by the intensive traffic and heavy vehicles in highways in settlement centers is aimed. When preparing the noise barrier system, it is considered that a double glass vacuumed insulation system placed on highway sides can prevent the noise, with the thought that the sound cannot propagate in space. A vehicle had been located and moved in the model road, and simultaneous noise measurements had been performed during the movement on both the road and outside of the double glass insulation system. After the results of noise measurements it is seen that the noise decreases by 14%-17% and reaches to acceptable normal conservation level 57-64 dB (decibel). Double glass insulation system had also prevented the panoroma pollution.