Low Traffic Intensity Research Articles

Improvement of Mohr-Coulomb criterion for designing pavements of roads of low traffic intensity

Improvement of Mohr-Coulomb criterion for designing pavements of roads of low traffic intensity

Quantification of Airborne Particulate Matter and Trace Element Deposition on Hedera helix and Senecio cineraria Leaves.

In both developed and developing countries, atmospheric pollution with particulate matter (PM) remains an important issue. Despite the health effects of poor air quality, studies on air pollution are often limited by the high costs of continuous monitoring and the need for extensive sampling. Furthermore, these particles are often enriched with potentially toxic trace elements and organic pollutants. This study evaluates both the composition of atmospheric dust accumulated during a certain timespan on Hedera helix and Senecio cineraria leaves and the potential for their use as bio-monitors. The test plants were positioned near automatic air quality monitoring stations at four different sites with respectively high, moderate and low traffic intensity. The gravimetric deposition of PM10 and PM2.5 on leaves was compared with data recorded by the monitoring stations and related to the weather conditions reported by Argentina's National Meteorological Service. To determine the presence of trace elements enriching the PM deposited on leaves, two analytical techniques were applied: XRF (not destructive) and ICP (destructive). The results indicated that only in the unpaved street location (site 2) did PM10 and PM2.5 concentrations (90 µg m-3 and 9 µg m-3) in the air exceed more than five times WHO guidelines (15 µg m-3 and 5 µg m-3). However, several trace elements were found to be enriching PM deposited on leaves from all sites. Predominantly, increased concentrations of Cd, Cu, Ti, Mn, Zn and Fe were found, which were associated with construction, traffic and unpaved street sources. Furthermore, based on its capability to sequester above 2800 µg cm-2 of PM10, 2450 µg cm-2 of PM2.5 and trace elements, Senecio cineraria can be taken into consideration for adoption as a bio-monitor or even for PM mitigation.

Traffic intensity and vegetation management affect flower‐visiting insects and their response to resources in road verges

Abstract Road verges can support high densities of flowers and could therefore provide new opportunities for the conservation of flower‐visiting insects. One way of optimizing road verges for vascular plant diversity is to adjust mowing regimes, but to date it is unclear how this affects flower‐visiting insects. Furthermore, for mobile organisms like wild bees and butterflies, there is a risk that the benefit of increased habitat quality in road verges is limited by the proximity to traffic, but this is poorly studied. In a crossed study design, we separated mowing time and frequency (early summer and autumn, or only late summer) from road verge habitat classification (valuable for biodiversity according to transport authority, or regular). We did so along a gradient of traffic intensity, to investigate if a mowing regime designed to enhance plant diversity can also benefit wild bees and butterflies, and if traffic limits the conservation potential of road verges. Road verges that were mown only in late summer had higher flower densities, and there was a positive relationship between flower density and wild bee abundance and species richness. Butterfly abundance and species richness only benefitted from a late summer mowing in valuable but not in regular road verges. Traffic intensity had a substantial negative impact on abundance and species richness of wild bees and butterflies. Higher traffic intensities limited the positive relationship between plant and butterfly species richness that we observed at lower traffic intensities. Increasing width of the road verges buffered negative effects of the traffic on wild bee as well as butterfly abundances, and on wild bee species richness. Synthesis and applications. Road verges can play a valuable role for the conservation of wild bees and butterflies, but there is a need to consider both traffic intensity and resource availability when implementing management strategies. To support wild bee and butterfly diversity, we recommend actions to enhance plant species richness and flower resource availability, and to focus these conservation efforts on roads with low traffic intensity, or on wide road verges.

Transient staffing at the beginning of work

Production and service systems often rely on stationary queueing formulas to determine the number of agents that need to be scheduled. However, this results in over-staffing decisions when the system starts empty. To address this issue, we propose a solution called transient staffing, which involves providing appointment times for agents to ensure that the expected queue length remains below a certain threshold. We model the system as a transient Erlang-A queue. To compute the appointment times, we employ a uniformized approximation that discretizes the elapsed time, which can be made as accurate as desired. We prove that the appointment times decrease with the arrival rate and traffic intensity, while increasing with the abandonment rate. Through numerical investigations, we find that adopting a transient staffing strategy leads to substantial cost savings, especially in scenarios where demand is high, customers are patient, traffic intensity is low, and the service level objective is intermediate. Furthermore, we use a fluid approximation to derive closed-form expressions for the agents' appointment times, and prove the impact of the system parameters. We show that this approximation performs well in predicting the first appointment times in contexts with high demand, low traffic intensity, and lax service level objective.

Spatial Identification and Hotspots of Ecological Risk from Heavy Metals in Urban Dust in the City of Cartagena, SE Spain

In the present work, a study has been carried out on the contamination of heavy metals in urban dust deposited on the roads of the city of Cartagena (Spain) in order to know the content of metals such as Ni, Zn, Pb, Cd, Cr and Cu. Likewise, the possible relationship between the concentration of heavy metals and the color of the sample, level of magnetism and traffic density was studied. Contamination was evaluated using several indices such as contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo), pollutant load index (PLI) and ecological risk index (RI). A total of 88 samples were taken in the urban area of Cartagena, and the metals were determined by acid digestion and measured by inductively coupled plasma mass spectrometry. The concentration of heavy metals in urban dust from Cartagena was Zn (672 mg kg−1) > Cu (248.9 mg kg−1) > Pb (227 mg kg−1) > Cr (82.7 mg kg−1) > Ni (47.7 mg kg−1) > Cd (4.1 mg kg−1). Contamination levels were high in Pb, Zn, Cd and Cu, according to environmental indices. A correlation was found between magnetism and metal concentration, which was repeated for all metals except Cd. Dark-colored samples contained higher metal concentrations than light-colored samples. Meanwhile, streets with medium and low traffic intensity were found to have higher concentrations of heavy metals. This study’s objective was to identify pollution hotspots caused by heavy metals in dust in the urban ecosystem of Cartagena city.

Assessment of the impact of ground-based skidding on soil physical properties: initial effect and medium-term recovery

ABSTRACT Soil profile disturbance and compaction can have a medium-term detrimental impact on soil physical properties. We investigated the recovery of physical properties of disturbed soils on four abandoned skid trails in a deciduous mountain forest in northern Iran. The trails ranged from immediately after skidding operations (IAS), through 5 years and 10 years, to 20 years since forest harvesting. For each recovery period, mean values for soil bulk density, total porosity, macroporosity, and rut depth were assessed for three levels of traffic intensity and two levels of slope gradients, as well as within the general harvesting area and compared to those in untrafficked control areas. Over the 20-year recovery period, skid trails with lower traffic intensity on gentle slopes exhibited mean values that were 16.1% (bulk density), and 3.5 cm (rut depth) greater and 9.5% (total porosity) and 32.7% (macroporosity) lower compared to undisturbed areas; on steep trails with higher traffic intensity, values were 43.1% (bulk density), and 13 cm (rut depth) greater and 30.3% (total porosity) and 64.5% (macroporosity) lower, respectively. During this period (over the 20-year recovery period), surface soil compaction showed recovery in the general harvesting area. These results raise serious concerns about medium-term resilience to traffic on forest soils and indicate the necessity to properly retire skid trails to avoid further soil degradation as trails age.

Effects on soil physicochemical properties and seedling growth in mixed high forests caused by cable skidder traffic

The use of wheel skidders for timber extraction from tree stump to roadside landing has become more and more widespread. Although the use of wheel skidders has the advantages of high production and reduced extraction costs, it also damages the soil and impedes forest regeneration. The main purpose of this study was to investigate the effect of machine traffic using the Timberjack 450C (two, six and 15 passes) on two slope classes (SC) of skid trails. A low slope is considered to be <20% and a high slope is at >20%. The effects on soil physicochemical properties and seedling growth (alder, Alnus subcordata C.A. Mey. and maple, Acer velutinum Boiss.) in natural mixed beech stands in the Hyrcanian forests in Northern Iran were observed and studied. The results showed that the different factors of traffic intensity (TI) and SC had a significant impact on soil physicochemical properties and subsequent seedling growth. After two machine passes in a low TI on both low and high slopes, soil bulk density (BD) increased by 49.3% and 59.2% and penetration resistance increased by 30.5% and 38.5%, while total porosity decreased by 19.5% and 23.5%. The forest floor decreased by 30.9% and 42%, organic carbon decreased by 25.6% and 39.4%, nitrogen decreased by 18.5% and 26.3%, phosphorus decreased by 14.1% and 23%, and potassium decreased by 10.7% and 24.2%, respectively as compared with the control area. Our results indicated additional BD increments after two, six and 15 machine passes of 49.3%, 17.9% and 8.3% in the low slope, respectively, and 59.2%, 16.5% and 7.1% in the high slope, respectively. The mean of the germination rate (GR) of alder and maple seedlings in the control area was 58.3% and 46.1%, respectively, while after two, six and 15 passes, the GR of alder seedlings reduced to 50%, 46.4% and 37.5%, respectively, while that of maple seedlings reduced to 36.1%, 28.6% and 25.6%, respectively. Additionally, after two machine passes, stem length, main root length, and total dry biomass decreased by 28.7%, 34.9% and 34% in alder seedlings, respectively, and 27.9%, 27.6% and 33.3% in maple seedlings, respectively. Comparison of the response of the two seedling species to soil compaction showed that although alder had a higher GR than maple, the root growth of maple was higher than that of alder.

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.

Black Carbon Personal Exposure during Commuting in the Metropolis of Karachi

Black carbon (BC) exposure and inhalation dose of a commuter using four traffic modes (car, bus, auto-rickshaw, and motorbike) were monitored in Karachi, Pakistan. The real-time exposure concentrations in office-peak and off-peak hours were recorded during the winter season using microAeth® AE51 BC monitors. Exposure concentrations were higher in peak hours and were reduced to half in the off-peak time. The inclination levels of the inhaled dose were similar, and this trend was observed with all four modes of commute. The motorbike was found to be the most exposed mode of transportation, followed by auto-rickshaws, cars, and buses, respectively. However, the order was reversed when accounting for inhaled doses, e.g., the inhalation dose for auto rickshaws was highest, followed by the bus, motorbike, and car, respectively. Spatiotemporal analysis reveals that driving roads with lower traffic intensity and fewer intersections resulted in lower exposures. Therefore, traffic intensity, road topology, the timing of the trip, and the degree of urbanization were found to be the major influences for in-vehicle BC exposure.

An analysis of particulate pollution using urban aerosol pollution island intensity over Delhi, India.

The accent of the present study is determination of Urban Aerosol Pollution Island (UAPI) intensity and spatial variability in particulate matter concentration (PM10 and PM2.5) over Delhi. For analysis, the hourly concentration dataset of PM2.5 and PM10 from January 2019 to December 2020 was obtained from ten air quality monitoring stations of Delhi. Additionally, UAPI Index has been calculated to assess the intensity of particulate pollution. The daily, monthly, and annual variations in the trends of PM10, PM2.5, and UAPI index along with related meteorological parameters have been analyzed. Particulate pollution peaked majorly during two seasons, i.e., summer and winter. The highest concentration of PM10 was observed to be 426.77 µg/m3 while that of PM2.5 was observed to be 301.91 µg/m3 in January 2019 for traffic-affected regions. During winters, higher PM2.5 concentration was observed which can be ascribed to increased local emissions and enhanced secondary particle formations. While the increase in PM10 concentrations led to an increment in pollution episodes during summers over most of the sites in Delhi. The UAPI index was found to be declining in 2020 over traffic affected regions (77.92 and 27.22 for 2019 and 2020, respectively) as well as in the background regions (64.91 and 19.80 for 2019 and 2020, respectively) of Delhi. Low traffic intensity and reduced pollutant emission could have been responsible for the reduction of UAPI intensity in the year 2020. The result indicates that lockdown implemented to control the COVID-19 outbreak led to an unexpected decrease in the PM10 pollution over Delhi.

Polycyclic Aromatic Hydrocarbons in Araucaria heterophylla Needles in Urban Areas: Evaluation of Sources and Road Characteristics.

Araucaria heterophylla needles were collected in urban areas of the city of Quito, Ecuador, to analyze the relationship between the concentration of polycyclic aromatic hydrocarbons (PAHs) with different emission sources and road characteristics. The PAHs were analyzed by high-performance liquid chromatography (HPLC) and included naphthalene (Naph), benzo[a]anthracene (BaA), chrysene (Chry), and benzo[a]pyrene (BaP), which are related to the sources considered in this work. The results indicated that some streets with moderate and low traffic intensity had higher total concentrations of PAHs than streets with high traffic intensity, showing the importance of non-traffic related emission sources and road characteristics on PAH emissions. All the studied PAHs were associated with traffic emissions, although Naph and BaP were more associated with acceleration and braking activities, while BaA and Chry also seemed to come from restaurant emissions. The presence of gas stations was also important in the emission of PAHs. Road capacity seems to have a higher effect on pollutant emission than road gradient and urban forms. The outcomes of this study are expected to facilitate the diagnostics of the concentration of PAHs in urban areas, which contribute to the design of strategies for the mitigation of pollution by PAHs in urban environment.

Bumblebee queen mortality along roads increase with traffic

Managing road verges to promote diverse and flower-rich plant communities has been proposed to mitigate the decline of pollinating insects caused by the loss of natural and semi-natural habitat. There is, however, a concern that flower-rich road verges can be ecological traps for pollinators as insects might be attracted to a habitat where there is a risk that they are killed by traffic. Therefore, we investigated the combined effects of traffic intensity and flowering plant diversity in road verges on the mortality and behaviour of bumblebee queens. The probability that an observed bumblebee queen was dead almost quadrupled when traffic increased from 100 to 6000 vehicles per day and tended to be lower when the flowering plant diversity in the road verge was high. Further, the number of nest-seeking bumblebee queens decreased dramatically with increasing traffic intensity in sites with low diversity of flowering plants, but not in sites with high diversity. Based on published data on bumblebee colony densities in different habitat types, we estimate that between 0.2 % and 32 % of all bumblebee queens present in our study landscapes were killed by traffic. We conclude that the flowering plant diversity in the road verge neither mitigates nor exacerbates the mortality from traffic. Road verges often provide pollinators with a high abundance of resources in florally poor landscapes. We therefore advise management to prioritise plant diversity along roads with low traffic intensity.

Comparison of Unbound Granular Materials’ Resilient Moduli Determined by Cyclic Triaxial Test and Innovative FWD Device

In addition to the conventional laboratory tests of input materials and construction mixtures, the technically correct design of pavement structure involves more frequent functional tests of the input materials and mixtures. Our study summarizes findings from a long-term monitoring of pavement on selected road sections with lower traffic intensity. The research involved the comparison of resilient moduli as a design parameter of unbound pavement base layers’ unbound granular materials (UGMs), determined in a laboratory by a test device for a cyclical triaxial test and in situ by impact load test using a falling weight deflectometer (FWD). In particular, the resilient moduli determined in the laboratory by a cyclic triaxial test (Mr,CTT) were compared with the real values of resilient moduli measured by FWD (Mr,FWD). A new, unique, and innovative FWD device was used to determine the Mr,FWD of the UGMs. The innovation lay in the dual-axis deflection measurement—measurement performed not just in the axis parallel to the road, but also in the axis in the transversal direction. It was found that, especially on roads with lower traffic load, such dual-axis (spatial) determination of Mr,FWD moduli was of great importance because it often allowed the identification of local pavement sections with low bearing capacities, especially at the edges, which have a significantly lower value of Mr,FWD.

Effects of Forest Harvesting Operations on the Recovery of Earthworms and Nematodes in the Hyrcanain Old-Growth Forest: Assessment, Mitigation, and Best Management Practice

The quality and performance of forest soil is closely related to the characteristics of the faunal community in the soil. Focusing on soil organisms can provide good indicators to choose the best soil restoration methods to improve the properties of degraded forest soils. Therefore, the present study aimed to evaluate the effects of the tree litter of different species on the recovery of soil organisms (earthworms and nematodes) from skid trails over a 20-year period after harvest operations. For this purpose, three skid trails with different ages after harvest operations (6, 10, and 20 years), considering three tree litter treatments (beech, beech–hornbeam, and mixed beech) and three traffic intensity classes (low, medium, and high), were identified. The combination of treatments was carried out in the forest with three replications, and a total of 18 sample plots of 0.5 m2 were harvested to measure earthworms and nematodes. The results showed that 20 years after harvest operations, the highest values of earthworm density (5.72 n m−2), earthworm biomass (97.18 mg m−2), and total nematodes (313.65 in 100 g of soil) were obtained in the mixed beech litter treatment compared to other litter treatments. With decreasing traffic intensity from high to low, the activity of soil organisms increased, and the highest values of earthworm density (5.46 n m−2), earthworm biomass (87.21 mg m−2), and soil nematodes (216.33 in 100 g soil) were associated with low traffic intensity. Additionally, in all three litter treatments and traffic intensities, the epigeic ecological species were more abundant than the anecic and endogeic species. Key soil variables including water content, porosity, available nutrients, pH, total organic C, and total N were significantly correlated with earthworm density and biomass and soil nematode population. Litter management and addition to compacted soil can support the functional dynamics and processes of the soil and maintenance of the abundances and activities of the soil fauna.

Анализ эффективности способов приоритета автобусам при проезде перекрестков с применением адаптивного управления светофорами

In recent years in the cities of the Russian Federation, within the framework of the national project “Safe and high-quality roads” the concept of “priority development of public transport” has been actively implemented and Intelligent transport systems have been created. The article discusses ways to prioritize public transport when passing through intersections using adaptive traffic light control as a possible alternative to a lane for route vehicles. The aim of the study is to reduce the loss of time for road users by determining the best ways to prioritize buses when passing regulated intersections, taking into account the number of passengers in public transport and the loss of time for all traffic participants. During the study, field observation methods, mathematical and simulation modeling were used. The account of the moments of the approach of buses to the regulated intersection and the analysis of the loss of time for buses when passing through the section on the central street of Tyumen was carried out. The scientific novelty lies in establishing the dependencies of the average speed of the bus on the approach to the intersection from the moment until the end of the traffic signal, the delay time of the buses on the number and moment of stopping the buses when passing the intersection. With the help of simulation micromodeling, the dependence of the delay time of buses and cars on traffic intensity was established for five options for priority to public transport. Two variants of priority for buses when passing through intersections are based on the methods of adaptive control of traffic lights and the algorithms “stage recall” and “green extension”. The use of a dedicated lane and the “stage recall” method at high traffic intensity reduces the delay time for buses by 94%, for personal vehicles – increases by 85%. At low traffic intensity, the delay time changes by 11 and 6%, respectively, for buses and cars. The use of the “green extension” method allows to reduce the total delay time by 3.2% with a high traffic volume (1900 veh/h) and a small number of buses (40 veh/h) and has a greater effect than the lane for fixed-route vehicles (deterioration by 148%). To determine the most efficient priority method, it is proposed to take into account the number of passengers in public transport. The dependence of the total delay time of all traffic participants on the traffic intensity of cars and buses with different priority methods has been established. This approach allows us to further determine the area of rational application of priority methods for public transport with the target function of reducing the loss of time for all traffic participants.

Taxonomic composition and condition of tree plantations of roadside strips in Kyiv

Aim. The analysis of the taxonomic composition and living condition of tree plantations of roadside strips in Kyiv. Methods. Determination of the species composition and viability of trees and shrubs was carried out by route survey on test areas along the routes with different traffic intensity. The plants living condition was established according to the methodology developed by us, which provides an integrated vitality assessment based on a set of morphometric, reproductive and phenological features. Results. It is established that in the conditions of traffic flow of high intensity 23, of moderate 27 and of low 29 species of trees and bushes were found on the test areas. The tree plants of most common genera and species of roadside plantations are identified. The plants living condition analysis showed, that in the conditions of traffic flow of high intensity, plants of moderate and low vitality predominate; while in the conditions of moderate and low traffic intensity, the predominant numbers of plants have high vitality. Conclusions. Analysis of the range of roadside plantations indicates its limited and almost complete absence of conifers. The species composition is not optimal and is not always determined by the degree of resistance to transport pollution specific conditions. The woody plants vitality is largely determined by the traffic intensity and compliance with care technology.

Increasing the Efficiency of Recuperation Through the Use of Energy Storage Systems for the Own Needs of Traction Substations

The use of regenerative braking by electric rolling stock on DC railways makes it possible to increase the energy efficiency of the transportation process. The effective use of regenerative braking is associated with creation of conditions for receiving energy obtained through it. For these purposes, rectifier-inverter converters and energy absorbing devices are currently used in the traction power supply system.A promising technology that provides an increase in theefficiency of the use of regenerative braking is energy storage, which allows this energy to be used in the future to cover the traction load curve. A feature of the use of regenerative braking on singletrack sections of DC railways with low traffic intensity is the need to use converters or energy absorbing devices. One of the options for increasing the efficiency of recuperation energy use is the adoption of energy storage systems for the own needs of traction substations. The use of this technical solution is advisable on single-track sections with intensive use of regenerative braking, the effectiveness of which is explained through a decrease in power consumption for own needs of the substation from the external grid.The international research allows us to identify the widespread trend towards the application of electricity storage technology in various fields: from renewable energy sources to electric power systems, including transport power supply systems. International practices demonstrate successful implementation of pilot projects of adoption of energy storage systems for solving problems of increasing the efficiency of electric urban and suburban transport, as well as of metro systems.The objective of the work is to assess the energy performance of energy storage systems when using recovered energy for own needs of a traction substation. The study is based on the methods of mathematical and simulation modelling, optimisation, and mathematical statistics.The discussed issues refer to the use of energy storage systems to provide power supply for own needs of DC traction substations. Main issues of operation of storage systems are considered with the help of a substation case study. The features of the recuperation load curve are described to explain the use of hybrid technologies for developing a storage system. The example of the considered traction substation helps to demonstrate the solution to the problem of determining main parameters of the storage system, considering the specifics of operation of electrochemical and electrical modules.

Optimal traffic routing in the network virtualization context

SummaryNetwork virtualization enables service providers to instantiate virtual networks on a common physical infrastructure. Virtual networks are then allocated to clients in order to deploy or test their services. Thus, clients do not know how their traffic is routed, which server is responding, and which path is crossed. Service providers who own the physical infrastructure aim to share the load among multiple servers for traffic routing. However, those who do not own the infrastructure and want to lease it essay to concentrate all the traffic on one server and exactly the closest server. In this paper, we model the problems of load sharing on multiple servers and traffic concentration on one server as two mathematical programs. The objective functions correspond to service providers' aims under a delay constraint based on the M/D/1/N queue's mean sojourn time's formula. Due to its hardness, we provide an approximation of the delay constraint at low and medium traffic intensities. The approximation is analytically proved by the Taylor series development at a chosen point. Finally, through simulation and analytical models, we compare the performance of programs' optimal solutions. We notice that load sharing decreases the packet loss and jitter values. However, traffic concentration reduces the latency.

A Balanced Algorithm for In-City Parking Allocation: A Case Study of Al Madinah City

Parking in heavily populated areas has been considered one of the main challenges in the transportation systems for the past two decades given the limited parking resources, especially in city centres. Drivers often waste long periods of time hunting for an empty parking spot, which causes congestion and consumes energy during the process. Thus, finding an optimal parking spot depends on several factors such as street traffic congestion, trip distance/time, the availability of a parking spot, the waiting time on the lot gate, and the parking fees. Designing a parking spot allocation algorithm that takes those factors into account is crucial for an efficient and high-availability parking service. We propose a smart routing and parking algorithm to allocate an optimal parking space given the aforementioned limiting factors. This algorithm supports choosing the appropriate travel route and parking lot while considering the real-time street traffic and candidate parking lots. A multi-objective function is introduced, with varying weights of the five factors to produce the optimal parking spot with the least congested route while achieving a balanced utilization for candidate parking lots and a balanced traffic distribution. A queueing model is also developed to investigate the availability rate in candidate parking lots while considering the arrival rate, departure rate, and the lot capacity. To evaluate the performance of the proposed algorithm, simulation scenarios have been performed for different cases of high and low traffic intensity rates. We have tested the algorithm on in-city parking facility in the city of Al Madinah as a case study. The results show that the proposed algorithm is effective in achieving a balanced utilization of the parking lots, reducing traffic congestion rates on all routes to candidate parking lots, and minimizing the driving time to the assigned parking spot. Additionally, the proposed algorithm outperforms the MADM algorithm in terms of the selected three metrics for the five periods.

Optimal server selection for competitive service providers in network virtualization context

Network Virtualization enables service providers to instantiate virtual networks while sharing the same physical infrastructure. Virtual networks are allocated to clients for deploying their services. In this context, clients are served without knowing which server is replying and which routing strategy is adopted. In this paper, we focus on the server selection problem for competitive service providers in Network Virtualization context. These latter do not own the physical infrastructure and aim to minimize the cost of leased resources while meeting their clients’ SLA (Service Level Agreement) targets. We propose a mixed integer linear program whose objective is to minimize latency under clients’ demand and server’s bandwidth constraints based on low and medium traffic intensities. We show that concentrating the traffic on the closest server yields an optimal solution. In addition, through simulation and analytical results, we show that Traffic Concentration reduces the response time, jitter, and node and link utilization compared to YouTube, random server selection, and equal load distribution of traffic among servers. However, the latter technique yields the best performance in terms of packet loss.