Traffic Intensity Research Articles

Fast noise mapping: A machine learning approach for predicting traffic noise indicators

Noise mapping has become a popular tool for assessing the impact of traffic noise on human health and wellbeing. Usually, models for estimating exposure of a population rely on a (standardized) simplification of the noise emission and propagation. Mapping is simplified by considering only the equivalent noise level since it removes all temporal information from the source prediction, the propagation, but unfortunately also from the impact assessment. Yet, it is known that noise events can play an important role in, e.g., sleep disturbance and temporal information are essential in the evaluation of outdoor soundscapes. Models for calculating spectro-temporal levels with a one-second resolution have been proposed, but these quickly become too slow for large scale exposure assessment. Here, a convolutional neural network (CNN) based on environmental characteristics is proposed as a fast alternative. The CNN-model is trained on thousands of detailed physical simulations with varying propagation conditions and traffic intensities on the surrounding roads. To increase the understanding of this machine learning model, Shapley values are used. They show the importance of different features in calculating indicators, e.g., loud events are mainly explained by close-by traffic, L50 by high intensity roads, also at larger distances.

The use of gravel crushing siftings sands for the production of cast emulsion-mineral mixtures «Slarri Sil»

In the article, the authors present the main use results of mineral materials from local open cast mines for the cast emulsion-mineral mixtures making «Slarri Sil» for the protective wearing course installation for asphalt concrete pavements. The production of cast emulsion-mineral mixtures «Slarri Sil» using sand sifting from crushing local gravel materials was carried out on regional category III highways (according to traffic intensity) of the Amur Federal Highway passing through the Amur Region. In accordance with the requirements for mineral materials for the production of cast emulsion-mineral mixtures «Slarri Sil», it was ruled to use the sandy fraction of the stone crushing sifting products of igneous rocks in accordance with National State Standard 8736 with the following properties quality indicators: strength grade greater than or equal to 1200, abrasion grade greater than or equal to I-1, frost resistance grade greater than or equal to F50. Due to the limited number of deposits with siftings for crushing dense rocks and the length of regional highways in the Amur Region, deposits use for the production of cast emulsion-mineral mixtures throughout the entire route make the construction of wear layers unprofitable. The research objective is the local sand and gravel mix of the Zeya and Bureya rivers for the production of Slurry Seal type cast emulsion-mineral mixtures. The authors present the results of determining the physical and mechanical parameters and grain compositions of sands from siftings of crushing sand and gravel mix and rock for protective wear layers of asphalt concrete pavements. The results of determining the adhesion of the binder with the mineral part of cast emulsion-mineral mixtures «Slarri Sil» on various sands of crushing siftings are presented. The results of testing sands from siftings of crushing gravel and siftings of igneous rocks for wet abrasion are shown. The results of experimental studies made it possible to substantiate the use of sand from gravel crushing siftings for the construction of a protective wear layer for asphalt concrete pavement made of cast emulsion-mineral mixtures type «Slarri Sil» on the roads of the Amur Region, including federal ones. The obtained results were used to prepare the standard of the organization company standard — closed stock corporation «Asfalt» — 001-2012 «Production of works on the installation of protective wear layers for asphalt concrete pavements from cast emulsion-mineral mixtures of the Slurry Seal type».

The economic impacts of COVID-19 and city lockdown: Early evidence from China

As the first major developing country heavily struck by the COVID-19 pandemic, China adopted the world's most stringent lockdown interventions to contain the virus spread. Using macro- and micro-level data, this paper shows that both the pandemic and lockdown policies have had negative and significant impacts on the economy. Gross regional product (GRP) fell by 9.5 and 0.3 percentage points in cities with and without lockdown interventions, respectively. These impacts represent a dramatic recession from China's average growth of 6.74% before the pandemic. The results indicate that lockdown explains 2.8 percentage points of the GDP loss. We also document significant spill-over effects of the pandemic in adjacent areas but no such effects of lockdown. Reduced labor mobility, land supply, and entrepreneurship are among the most significant mechanisms underpinning the impacts of the pandemic and lockdown. Cities with higher share of secondary industry, higher traffic intensity, lower population density, lower internet access, and lower fiscal capacity suffered more. However, these cities seem to have recovered well from the recession and quickly closed the economic gap in the aftermath of the pandemic and city lockdown. Our findings have broader implications for the global interventions in pandemic containment.

How Much Impact Has the Cover Crop Mulch in Mitigating Soil Compaction?—A Field Study in North Italy

Soil compaction was largely studied in different scenarios with laboratory and field scale experiments, with various soil conditions and traffic intensities. However, a detailed analysis to better understand the protective role of plant residues or cover crop mulch is still required. A field test was conducted in Northeast Italy aiming to fill this gap. Rye was chosen as a winter cover crop, and growth on a controlled traffic random block experimental field. Four different cover crop mulch treatments were compared to study the effects of root systems: roller crimper, flail mower, bare soil control and harvested biomass control. Four different traffic intensities were used to evaluate the multiple passages with 0, 1, 3, 5 traffic events. During traffic events, the mean normal stress was measured. Penetration resistance was then evaluated after trafficking and soil samples were collected. The obtained results showed a 19.3% cone index increase in bare soil compared to flail mower treatment after the first traffic event, while low differences were found in harvested biomass bulk density during the first and third traffic events. Moreover, mean normal stress increased 16.5% on harvested biomass treatment compared to the flail mower. These findings highlight that the cover crop maintains a lower soil penetration resistance during compaction events, helping the subsequent field operations. Furthermore, roller crimper and flail mower cover crop termination impact soil bearing capacity differently due to different soil moisture content. However, the results showed a low contribution of cover crop mulch on mitigating soil compaction effects during the experiment.

Road traffic-induced particle matter dispersion in a calm wind environment at the main roundabout in Douala, central Africa


 
 
 
 Introduction: Road traffic emissions are among the most significant sources of pollution in Douala, Cameroon's economic town, alongside industrial operations. The morning and the evening are two times of the day when traffic is heavier and the winds are also at their calmest. The majority of the non-exhaust Particulate Matters (PMs) produced by autos is re-suspended road contaminants. The purpose of this research is to estimate fine particle dispersion in conditions of calm winds.
 Materials and methods: In one of Douala's roundabouts, the Gaussian Plume model is employed to calculate the PM concentration under calm winds conditions. Different vehicle classes (HDV: Heavy Duty Vehicles, LDV: Light Duty Vehicles, PC: Passenger Cars) are used to figure out the amount of PMs they produce. Measurements of ambient fine particle concentrations are made with the OC-300 laser dust particle detector.
 Results: The results made it possible to compare actual measurements of PM2.5, PM10 (300±150 μg/m3 and 650±150 μg/m3, respectively) with simulated values (PM2.5, PM10: 310 μg/m3 and 631 μg/m3, respectively). The difference between in-situ and computed values can range from 10 to 132 μg/m3. From 6 to 10 AM, the population's exposure to PM pollution is more severe. It has also been demonstrated that there is a significant association between traffic flow and PM Concentration during the dry season (R2=0.921). With increased traffic flow intensity, particle concentration levels rise.
 Conclusion: The concentration threshold stays above the World Health Organization (WHO) limits regardless of the approach. Furthermore, this paper provides important information about Douala's pollution levels.
 
 
 

Approximate waiting times for queuing systems with variable long-term correlated arrival rates

We consider waiting times in queuing systems with variable arrival rates in the presence of long-term correlations and periodic trends. We focus on a simplified model where the contributions of periodic and stochastic components could be analyzed separately, leading to queue lengths exhibiting periodic and stochastic resetting, respectively, with their effects summarized additively. We provide an approximate analytical solution that is based on the universal scaling of return interval statistics between level crossing events in long-term correlated data series. The accuracy of our results is validated explicitly by computer modeling, using both simulated data series and empirical traffic data from a network cluster hosting the World Cup ’98 web services characterized by extremely variable traffic intensity. We believe that the proposed approach could be useful to characterize the impact of long-term correlations and periodic trends in various complex systems, with prominent examples ranging from information, communication, logistic, transportation networks to climate, hydrological, as well as other natural, social and engineering systems.

A methodology to assess a mobile urban street cleaning activity

An experimental methodology to assess the human exposure of a street cleaning service, performed by a worker handling a leaf blower followed by a water-flushing sweeper, was developed. The sampling campaign was achieved by considering data from road dust, personal air sampling and portable particulate matter detector. The experimental design allowed to obtain qualitative and quantitative information on the chemical composition of road dust, the size and chemical composition of potentially inhalable particles suspended during the street cleaning activity, as well as the duration of the particles' suspension effect. The methodology employed showed: i) the compliance with the occupational exposure threshold values for the total inhalable dust and with the occupational exposure limit values according to national and international regulatory approaches for polycyclic aromatic hydrocarbons (PAH) and inorganic elements; ii) a good agreement of the metals concentrations from the road dust (i.e., calcium, magnesium, potassium, iron, aluminium and sodium) with those from the material collected by the personal air sampler, highlighting the negligible effect of the investigated sweeping activity compared to the material already present on the road; iii) a similar pattern of inorganic elements within the three different monitoring areas; iv) a “dust wave” effect detected by the particle counter lasting no more than 2 min. Thus, such information suggested that performing the urban sweeping activity in the early mornings, when there is a general low PM10-PM2.5 average concentration, low traffic intensity, and the almost absence of passers-by, lead to a low probability of citizens’ exposure.

An Optimization Model for Structuring a Car-Sharing Fleet Considering Traffic Congestion Intensity

Ever-growing mobility and traffic congestion within urban areas make the need for a sustainable form of transport inevitable. Traffic congestion has a significant effect on the amount of energy consumption of a vehicle and, as a result, on its associated environmental impacts. Any decision-making regarding structuring a fleet without taking into account the traffic congestion level (TCL) will lead to a less sustainable fleet with higher environmental and economic costs. To address this issue, this study examines the effects of the traffic congestion intensity level on the fleet structure of an urban car-sharing company over a certain planning period. We present a new optimization framework for finding an optimal vehicle composition of the fleet of an urban car-sharing company considering the energy consumption of vehicles at different traffic congestion levels. The results show that electric vehicles (EVs) are more competitive than diesel vehicles (DVs) in high-peak traffic congestion from the outset of the planning period. In addition, we perform a sensitivity analysis to take into account the effects of specific uncertain parameters such as the energy and purchasing costs of EVs on the total cost of ownership. As expected, the purchasing price of EVs, energy prices of DVs, and increase in diesel prices have the highest impact on the total cost.

Accumulation of antimony and lead in leaves and needles of trees: The role of traffic emissions

Antimony (Sb) is a toxic metalloid, which has been increasingly used in the brake lining of vehicles, and increased concentrations have been found in soils near abundant traffic. However, since very few investigations of Sb accumulation in urban vegetation have been undertaken there exists a knowledge gap. We studied the concentrations of Sb in leaves and needles of trees in the Gothenburg City area, Sweden. In addition, lead (Pb), also associated with traffic, was investigated. Sb and Pb concentrations of Quercus palustris leaves at seven sites with contrasting traffic intensity varied substantially, correlated with the traffic-related PAH (polycyclic aromatic hydrocarbon) air pollution at the sites and increased during the growing season. Sb but not Pb concentrations were significantly higher in needles of Picea abies and Pinus sylvestris near major roads compared to sites at larger distances. In Pinus nigra needles at two urban streets both Sb and Pb were higher compared to an urban nature park environment, emphasising the role of traffic emissions for these elements. A continued accumulation of Sb and Pb in three years old needles of Pinus nigra, two years old needles of Pinus sylvestris and eleven years old needles of Picea abies was observed. Our data suggest a pronounced link between traffic pollution and Sb accumulation in leaves and needles, where the particles carrying Sb seem not to be transported very far from the source. We also conclude that there exists a strong potential for Sb and Pb bioaccumulation over time in leaves and needles. Implications of these findings are that increased concentrations of toxic Sb and Pb are likely to prevail in environments with high traffic intensity and that Sb can enter the ecological food chain by accumulation in leaves and needles, which is important for the biogeochemical cycling.

On-board measurements using two successive vehicles to assess in-cabin concentrations of on-road pollutants

Gaseous and particulate pollutants are produced in large quantities from road vehicles. These traffic-related air pollutants can infiltrate the car-cabins exposing drivers and passengers to toxic substances with serious adverse health effects. The infiltration process depends on many parameters, those from outside of the vehicle (e.g. traffic intensity, meteorology, road type) and those depending on the vehicle itself such as the ventilation and/or the vehicle speed/age. In the present study, we undertook on-road measurements to assess the impact of ventilation and vehicles spacing (proximity effect) on in-cabin to on-road (I/O) concentration ratios of nitrogen oxides (NOx) and ultrafine particles (UFP). The novelty of the present work is that two successive vehicles have been used to circumvent the influence of the emissions of the upstream vehicle on the downstream test vehicle. We show that the distance to the upstream vehicle influences significantly the (I/O) ratios. Overall, the results show that car cabin is less polluted when the ventilation is set to recirculation mode and keeping a distance to the upstream car corresponding to twice its height in non-idle conditions.

A Lightweight Method for Detecting Cyber Attacks in High-traffic Large Networks based on Clustering Techniques

Protecting information systems is a difficult and long-term task. The size and traffic intensity of computer networks are diverse and no one protection solution is universal for all cases. A certain solution protects well in the campus network, but it is unlikely to protect well in the service provider's network. A key component of a cyber defence system is a network attack detector. This component needs to be designed to have a good way to scale detection capabilities with network size and traffic intensity beyond the size and intensity of a campus network. From this point of view, this paper aims to build a network attack detection method suitable for the scale of large and high-traffic networks based on machine learning models using clustering techniques and our proposed detection technique. The detection technique is different from outlier detection commonly used in clustering-based anomaly detection applications. The method was evaluated in cases using different feature extraction methods and different clustering algorithms. Experimental results on the NSL-KDD data set are positive with a detection accuracy of over 97%.

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.

Congestion Problem during Covid-19 in the University College Hospital, Ibadan, Oyo State, Nigeria: An Application of Queuing Theory

Outpatient services have become an important component of healthcare especially during the era of pandemic (Covid-19). The amount of time a patient spends waiting in an outpatient setting may have an impact on their satisfaction with the service(s) provided. In this research, an attempt was made to investigate the arrival and service rates of patients for the period of one month between the hours of 9:00am and 2:00pm at the University College Hospital (UCH), Ibadan during Covid-19 using Poisson Process in order to deduce traffic intensity (ρ), expected number of patients at a steady rate (L), expected queue length (Lq), expected waiting time (Wq), total patients waiting (W) and mean number of Patients in the system. Results showed that more patients visit the clinic everyday of the week due to the high traffic intensity close to 100% and the high minutes spent in the hospital before being attended to. Conclusively, waiting time on Saturdays and Tuesdays are much compared to the remaining days.

Mobile measurements of black carbon: Comparison of normal traffic with reduced traffic conditions during COVID-19 lock-down

A mobile monitoring campaign was conducted (by bicycle) to assess the black carbon (BC) concentrations in Cluj-Napoca city, Romania, in 2020, before, during and after COVID-19 lock-down. Over the entire study period, the BC concentrations ranged between 1.0 and 25.9 μg/m³ (averaged per street section and period characterized by different traffic conditions). Marked spatial and temporal differences were observed. Observed differences in BC concentrations between locations are attributed to traffic intensities, with average BC concentrations, under normal circumstances, of 6.6–14.3 μg/m³ at roads with high to intense traffic, compared to 2.8–3.1 μg/m³ at areas with reduced traffic, such as residential areas, parks and pedestrian streets. The COVID-19 measures impacted traffic volumes, and hence average BC concentrations decreased from 5.9 μg/m³ to 3.0 μg/m³ during lock-down and in a lower extent to 3.4 μg/m³ and 4.4 μg/m³ in post-lockdown periods with reduced and more normalized traffic. Two approaches to account for variations in background concentrations when comparing different situations in time are assessed. Subtracting background concentrations that are measured at background sites along the monitoring route is an appropriate method to assess spatio-temporal differences in concentrations. A reduction of about 1–2 μg/m³ was observed for the streets with low to medium traffic, and up to 6 μg/m³ at high traffic locations under lockdown. The approach presented in this study, using mobile measurements, is useful to understand the personal exposure to BC along the roads in different seasons and the influence of traffic reduction on BC pollution during prolonged restrictions. All these will support policymakers to reduce pollution and achieve EU directives targets and WHO recommendations.

Corrosion Fatigue Degradation Characteristics of Galvanized and Galfan High-Strength Steel Wire.

Cables are the main load-bearing components of a cable bridge and typically composed of high strength steel wires with a galvanized coating or Galfan coating. Galfan steel wire has recently started to be widely used because of its better corrosion resistance than galvanized steel wire. The corrosion characteristics of the coating and the difference in the corrosion fatigue process of the two types of steel wire are unclear. To further improve the service performance and maintenance of cable bridges, this study investigated the corrosion characteristics of galvanized steel wire and Galfan steel wire through accelerated corrosion tests and established a time-varying model of uniform corrosion and pitting corrosion of high-strength steel wire. Then, a long-span suspension bridge was taken as the research object, and the corrosion fatigue degradation of the two kinds of steel wire under a traffic load was analyzed on the basis of traffic monitoring data. The results showed that the uniform corrosion of the two types of steel wire conformed to an exponential development trend, the corrosion coefficient of galvanized steel wire conformed to the normal distribution, and the corrosion coefficient of Galfan steel wire conformed to the Cauchy distribution. The maximum pitting coefficient distribution of the two kinds of steel wire conformed to the generalized extreme value distribution. The location parameters and scale parameters of the two distributions showed an exponential downward trend with the increase of corrosion duration. When the traffic intensity was low, the corrosion characteristics of the steel wire was the main factor affecting its service life, and the average service life of Galfan steel wire was significantly higher than that of galvanized steel wire. Under a dense traffic flow, the service life of the steel wire was mainly controlled by the traffic load, and the service life of Galfan steel wire was slightly improved. Effective anti-corrosion measures are a key factor for improving the service life of steel wire.

A Comparative Study of Air Pollutant Concentrations before the COVID-19 Pandemic and in the New Normal in the Región de Murcia (Spain)

The management of the COVID-19 pandemic, which required global lockdowns and mobility restrictions, positively impacted air quality (especially the concentrations of primary pollutants). With the progressive return to normal activity during the last few months of 2020 and 2021, air pollutant concentrations were expected to rise again. In this work, together with meteorological conditions and traffic intensity, the concentrations of NO, NO2, O3, PM10, and SO2 measured at three different locations (urban, industrial, and rural) in southeast Spain, from January 2016 to December 2021, were analyzed. For the three locations, PM10 concentrations did not change significantly in 2020 or 2021. SO2 concentrations did not experience changes at the industrial site in 2020 or 2021, but SO2 concentrations did slightly increase in five months of 2021 in the urban location (with a maximum monthly average concentration of 11 μg·m−3). In 2020, NO and NO2 concentrations were, in general, lower than those measured in previous years (2016–2019). Interestingly, at the urban site (San Basilio), the levels of NO and NO2 were significantly lower in 2021 than in 2020 despite the higher traffic intensity in 2021. While the concentrations of NO and NO2 decreased, in VOC-limited areas, O3 concentrations increased. This was clearly observed at the industrial and the urban sites. Despite the increase, O3 concentrations were still below the European O3 target value for the protection of human health. An analysis of new registrations of EVs and HEVs in the latter years and their impact on the vehicle fleet of Murcia and, subsequently, on road emissions was carried out. Regardless of the steep increase in environmentally friendly vehicles in 2021, their share of the vehicle fleet is still negligible; thus, the lower concentrations of NO and NO2 are likely due to more favorable weather conditions in 2021 than in 2020.

Energy Efficiency Improvement with Reversible Substations for Electrified Transportation Systems

More and more often overall energy efficiency of an electrified transportation system appears as target of new constructions, sometimes with incomplete definitions of performance indexes to assess that target has been reached. A worked out example is based on the introduction of reversible substations. Reversible substations are a method to improve energy efficiency, whose application in an existing system can be progressive and does not require large traffic intensity to be effective. Their effectiveness depends on some system parameters (nominal catenary voltage in particular). A simulation model fed with experimental data from a line section of Metro de Madrid is used to demonstrate the operation and optimization of reversible substations. Background The ambitious reduction of CO2 greenhouse gas emission within 2050 declared by the European Commission also involves transportation systems. In this context an optimum recovery of the electric braking energy produced by railway vehicles is more and more relevant. Several strategies to completely recover the braking energy are being developed and applied. A methodology that allows the accurate determination of the amount of recovered energy in real operating conditions becomes then a valuable tool. Objective Reversible substations are one of the braking energy recovery methods that are widely applicable. Their effect is analyzed in a system perspective, considering them integrated in the transportation system with its dynamics and various operating points. The effectiveness and consequences of the operation of one or more reversible substations are evaluated by identifying relevant system conditions and scenarios. Methods An electric network model is provided, fed by measured timetable and traction current. Simulation results are analyzed and compared with some experimental results: simulation configurations will be selected to match those of the available experimental data. Results The selected substation no-load output voltage level has a significant effect on efficiency and performance of reversible substations. A reduction of 50 V, from 1700 V to 1650 V produces a decrease of the energy dissipated by the braking rheostat on-board trains of about 13%. The voltage increase caused during braking phases is kept under control better for track positions close to reversible substations: tests show that line voltage increase is 2.5% of nominal value with a reversible substation, and only 0.5% when it is operated. Trimming the thresholds that trigger the operation of the on-board braking chopper (intermingling regenerative and dissipative braking) has a dramatic effect on regenerability: a reduction of 50 V causes an improvement of 19%. Conclusion The paper presents a methodology that merges measurements and circuital model to investigate on the energy saving provided by reversible substations supplying railway system. The methodology has been applied to a real case. Preliminary results regarding the impact of supply voltage level, reversible module position and threshold levels of the braking chopper control system on the dissipated braking energy and power quality has been carried out.

Experimental Evaluation of the Layered Flow-Based Autonomous TSCH Scheduler

The Industrial Internet of Things (IIoT) requires wireless connectivity that meets the strict industrial requirements on metrics such as reliability and latency. Promising approaches include Time Slotted Channel Hopping (TSCH) media access, where nodes operate according to a schedule. Autonomously built schedules typically rely on shared resources, where reliability and latency may suffer depending on traffic scenarios and topologies. We have earlier proposed the Layered scheduler, which belongs to a new category of autonomous schedulers: Flow-based scheduling. Layered allocates resources to traffic flows, and as opposed to typical autonomous schedulers, dedicated resources are guaranteed to be scheduled at every hop from source to destination in a convergecast scenario. In addition, Layered minimizes the number of channels required through the novel employment of autonomous spatial reuse. We extend earlier theoretical analysis and simulations by evaluating Layered using the FIT IoT-LAB testbed and compare it to Orchestra and 6TiSCH Minimal scheduler. The experiments demonstrate the feasibility of spatial reuse and that Layered retains performance independent of network topology and traffic intensity - a desirable feature in industrial scenarios. The performance comes at the expense of energy consumption, which in the worst case is 75 % higher compared to Orchestra and Minimal. We also present lessons learned, such as the impact of TSCH configuration on RPL convergence, the benefits of black-listing on performance, and how co-located TSCH networks could be divided by channel offsets as opposed to physical channels. Lastly, we discuss flow-based scheduling in general, its properties, and future research areas.

THE METHOD OF EXPERIMENTAL STUDY OF THE DISTRIBUTION OF TRAFFIC INTERVALS IN THE TRANSPORT FLOW

The method of experimental determination of the distribution of traffic intervals between cars in the traffic flow on the sections of races between simple interchanges on the same level with a traffic intensity of 300 to 600 vehicles per hour per lane is described, as well as the influence of interchanges on the same level on the time interval is established and on the change in traffic intensity to determine the dependence of the availability and number of free traffic intervals in the traffic flow. For this purpose, the following tasks were solved: a method of experimental research on changing traffic intervals in the traffic flow was developed; the necessary amount of data is established to ensure the necessary reliability of the results; the experimental part was carried out (collection of statistical data on traffic intensities and intervals and other characteristics on different categories of highways); processing of experimental data using methods of mathematical statistics; specified time interval distribution function; analyzed the nature of the change in time intervals between vehicles in a "package" and between "packages" when moving through intersections at the same level; the dependence of the number of vehicles of a given traffic interval on the time interval between vehicles is established.

The Environmental Consequence of Automobile and Motor-bike Traffic Noise Intensity on the Activity of African Grey Parrots (Psithacus erittacus) in Limbe Botanic Garden, Southwest Region, Cameroon

Highway traffic noise pollution is unavoidably generated by human activity, and has caused serious health problems to the human society. However, it’s also a challenge to many wildlife species, though, continous exposure to the noise stimuli has seemingly given them adaptation. Understanding the ability of wildlife species to cope with noise pollution is complex, thus, requires research. Therefore, the objective of this study was to explore automobile and motor bike traffic noise intensity on African grey parrots’ activity in Limbe Botanic Garden. The research data was collected for a period of three months from 8:00 am - 5:00 pm each day. Traffic noise pollution is difficult to avoid in urban settings because of huge human population and its activity, however, its interference with other sounds is common, and wildlife population living in cities, such as birds are affected. The study revealed a positive significance X2 = 25.796 df=2 P=0.000 and X2 =39.489 df=6 P=0.000 on photoperiod and meteorological conditions respectively. Moreover, meteorological changes in the study area recorded significance on sun 75%, cloud 15%, wind 6%, and rain 4% respectively. Furthermore, noise intensity of automobile and motor bike traffic around the botanic garden area showed a significance X2 = 5.657 df=8 P<0.05, and r = 0.209 P=0.000 on behavior and parrots' food availability respectively. The highest parrots’ activity recorded during this study was on contact calls 54%, and the least was roosting 3%. Though a comprehensive inventory is not carried out on the parrot population in Cameroon, there are signs, these birds are already facing population reduction; principally because of the pet-trade driven by the craving human love for the colourful plumage morphology and the talented sound-mimicking behavior of the parrots. There is a necessity for further study to be carried out on the birds’ population census in the country. The study found that traffic noise intensity at all levels have a negative influence on the aggregation activity of grey parrots, reason why they avoid the vegetation along the streets of the garden. Finally, oil palm fruit-feeding was a dominant activity recorded in this study, hence, we recommend more oil palm trees be planted in the garden far from major roads to enrich the feeding environment of the grey parrots.