Traffic Growth Rate Research Articles

Migration cost analysis for upgrading WDM networks

We present a generic step-by-step methodology for evaluating the total cost of migrating from a capacity-exhausted WDM network to different upgraded alternatives. The presented methodology is the first effort to provide a generic evaluation framework (allowing the evaluation of scenarios with different traffic growth rates, optical technologies, network architectures, and resource allocation algorithms) that considers both capital and operational expenditures of the upgraded alternatives to then identify the lowest-cost option. Previous works have just evaluated specific scenarios or only CapEx or OpEx (not both). As a way of illustration, the proposed methodology was applied to compare the migration cost of two upgrading scenarios. The methodology allowed identifying the lowest-cost alternative, categorizing the key cost factors of CapEx and OpEx, and evaluating its impact on the migration cost. Surprisingly, results for the study case presented show that migrating to an automatically provisioned network does not necessarily lead to cost savings.

Rating of steel bridges considering fatigue and corrosion

In the present work, the capacity ratings of steel truss bridges have been carried out incorporating dynamic effect of moving vehicles and its accumulating effect as fatigue. Further, corrosion in the steel members has been taken into account to examine the rating factor. Dynamic effect has been considered in the rating procedure making use of impact factors obtained from simulation studies as well as from codal guidelines. A steel truss bridge has been considered to illustrate the approach. Two levels of capacity ratings- the upper load level capacity rating (called operating rating) and the lower load level capacity rating (called inventory rating) were found out using Load and Resistance Factor Design (LRFD) method and a proposal has been made which incorporates fatigue in the rating formula. Random nature of corrosion on the steel member has been taken into account in the rating by considering reduced member strength. Partial safety factor for each truss member has been obtained from the fatigue reliability index considering random variables on the fatigue parameters, traffic growth rate and accumulated number of stress cycle using appropriate probability density function. The bridge has been modeled using Finite Element software. Regressions of rating factor versus vehicle gross weight have been obtained. Results show that rating factor decreases when the impact factor other than those in the codal provisions are considered. The consideration of fatigue and member corrosion gives a lower value of rating factor compared to those when both the effects are ignored. In addition to this, the study reveals that rating factor decreases when the vehicle gross weight is increased.

Traffic and revenue forecast at risk for a BOT road project

This paper presents the risk analysis of revenue and traffic forecast of a Build Operate Transfer (BOT) road project using cumulative distribution method. In road project, traffic is the main source to earn money/revenue. Traffic is projected using various methods. Actual traffic may not follow the projected traffic and actual traffic may be reduced/increased depending on the development of the road side and near areas. Rapid development i.e., industrial, commercial, business activity creates rapid traffic growth rate which is not expected and reverse happening where road side development is negligible. Traditional traffic forecast may not consider the risk of projected traffic. This paper presents the risk analysis of the projected traffic and alternatively revenue with a real case study and determine lower and upper limit of revenue and expected revenue has been determined using Monte Carlo Simulation Method.

Emission consequences of introducing bio ethanol as a fuel for gasoline cars

This article describes the direct vehicle emission impact of the future use of bio ethanol as a fuel for gasoline cars in Denmark arising from the vehicle specific fuel consumption and emission differences between neat gasoline (E0) and E5/E85 gasoline-ethanol fuel blends derived from emission tests using primarily the European NEDC and ARTEMIS driving cycles. The E0-E5 test vehicles (nine cars) represent today’s gasoline car traffic well where most of the driving is being made with cars certified as Euro 3+. The FFV test cars (25 cars) are all certified according to the Euro 4 emission standard introduced in Europe from the mid-2000s. This matches well with the propagation of the FFV technology in Europe.For vehicles using E5 rather than E0, the average fuel consumption and emission differences are small. For CO, VOC and NOx the derived average differences are 0.5%, −5% and 7%, respectively. For FFVs using E85 rather than E5, the emission differences become even smaller for VOC and NOx, but greater for CO. The derived average emission differences are in this case 18%, −1% and 5% for CO, VOC and NOx, respectively. In both comparative cases there is a large variation in the emission difference values calculated for the individual cars. The large standard deviations introduce some uncertainties in the final averages computed for each emission component.The vehicle based emissions are made up for two fossil fuel baseline scenarios (FS), characterised by high and low traffic growth rates. For each FS, two biofuel scenarios (BS1, BS2) are presented. BS1 reaches the Danish policy targets (10% biofuel share in 2020). BS2 is more ambitious (25% in 2030). By definition the biofuel part of the combusted fuel is CO2 neutral and the maximum CO2 emission difference between FS and BS2 becomes 27% in 2030. As predicted by the vehicle specific emission differences the calculated emission impacts of using bio ethanol are small for NOx, VOC and CO. Instead, for FS, BS1 and BS2 large emission reductions are due to the gradually cleaner new sold gasoline cars and the decline in total mileage until the mid-2010s.

A high‐performance switch architecture based on mesh of trees

SUMMARYWith emergence of various new Internet‐enabled devices, such as tablet PCs or smart phones along with their own applications, the traffic growth rate is getting faster and faster these days and demands more communication bandwidth at even faster rate than before. To accommodate this ever‐increasing network traffic, even faster Internet routers are required. To respond for these needs, we propose a new mesh of trees based switch architecture, called MOTS(N) switch. In addition, we also propose two more variations of MOTS(N) to further improve it. MOTS(N) is inspired by crossbar with crosspoint buffers. It forms a binary tree for each output line, where each gridpoint buffer is a leaf node and each internal node is 2‐in 1‐out merge buffer emulating FIFO queues. Because of this FIFO characteristic of internal buffers, MOTS(N) ensures QoS like FIFO output‐queued switch. The root node of the tree for each output line is the only component connected to the output port where each cell is transmitted to output port without any contention. To limit the number of buffers in MOTS(N) switch, we present one of its improved (practical) variations, IMOTS(N) switch, as well. For IMOTS(N) switch architecture, sizes of the buffers in the fabric are limited by a certain amount. As a downside of IMOTS(N), however, every cell should go through log 2N + 1 number of buffers in the fabric to be transmitted to the designated output line. Therefore, for even further improvement, IMOTS(N) with cut‐through, denoted as IMOTS‐CT(N), is also proposed in this paper. In IMOTS‐CT(N) switch, the cells can cut through one or more empty buffers to be transferred from inputs to outputs with simple 1 or 2 bit signal exchanges between buffers. We analyze the throughput of MOTS(N), IMOTS(N), and IMOTS‐CT(N) switches and show that they can achieve 100% throughput under Bernoulli independent and identically distributed uniform traffic. Our quantitative simulation results validate the theoretical analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Effectiveness of Traffic Forecasting on Pavement Designs for Sri Lankan Roads

Pavement design plays an important role in any improvement or rehabilitation. It is a responsibility of the road design Engineer to ensure that he has come up with an effective design, so that it will last for the design life. This effectiveness or the optimization is very important as otherwise it could lead to financial implications. The method adopted for the design of flexible pavements is the TRL, Road Note 31. The two main parameters considered in the design of the pavements under Road Note 31 are Cumulative Number of Standard Axles (CNSA) (i.e. Traffic Class) and the sub-grade strength (i.e. California Bearing Ratio (CBR)% class). In this research study, flexible pavement designs of recently rehabilitated or improved set of roads were analyzed to check the effectiveness of the traffic forecasting on pavement design. As the subgrade strength of the pavements is a fixed parameter in all the cases, the only possible variable is the Traffic Class relevant to predicted CNSA. It was found in the study that the actual traffic growth rates of different modes of traffic which travels along the selected roads is different to the predicted rates at the time of design. It has also been shown and statistically proved that the Equivalent Standard Axles (ESA) values actually applied on these pavements by large trucks / heavy goods vehicles are significantly high, compared to the ESA values recorded at the design stage. The authors have proposed a methodology to evaluate the effectiveness of traffic forecasting on pavement designs, and improvements to the present practice of pavement designs carried out by the Road Development Authority (RDA) and its presentation.

New approaches in the new chapter of telecommunications

Over the last few years, the telecommunications industry has faced significant changes fueled by the mass market adoption of smartphones. Smartphones have created the need for more data-centric network services by accelerating the introduction of new applications and services. This evolution has helped wireless broadband service mature as a next wave of communication. In particular, due to the migration of Internet use on fixed network to mobile network, the mobile data traffic growth rate has grown beyond network capacity. Overall mobile data traffic in Korea is expected to grow to 152 petabytes (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> bytes) per month by 20 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> , a 35-fold increase over 2010 according to KCC(Korea Communications Commission).

Heavy-traffic analysis of mean response time under Shortest Remaining Processing Time

Shortest Remaining Processing time (SRPT) has long been known to optimize the queue length distribution and the mean response time (a.k.a. flow time, sojourn time). As such, it has been the focus of a wide body of analysis. However, results about the heavy-traffic behavior of SRPT have only recently started to emerge. In this work, we characterize the growth rate of the mean response time under SRPT in the M/GI/1 system under general job size distributions. Our results illustrate the relationship between the job size tail and the heavy traffic growth rate of mean response time. Further, we show that the heavy traffic growth rate can be used to provide an accurate approximation for mean response time outside of heavy traffic regime.

Viability of new road infrastructure with heterogeneous users

This paper explores the importance of heterogeneity in value of time and route choice when assessing the viability of new road infrastructure to alleviate congestion problems. The model incorporates strategic interaction between road operators in a cost-benefit framework and several competitive regimes are considered. It is then employed to establish the financial and socio-economic viability of a congestion pricing demonstration entering Madrid city centre, where road users have to choose between a free but highly congested road and a priced free-flowing road (semi-private regime). A logit estimation is undertaken with information from a questionnaire among road users in the Eastern Madrid area to obtain users’ value of time and of congestion. The tolls obtained generate a traffic reallocation towards the new roadway such that revenues suffice to render the infrastructure socio-economically viable. The private and the low toll regimes generate similar welfare gains that are close to the first best. Yet the former supposes large losses to users. The low toll and the semi-private regimes do not raise such distributional concerns. However, the low toll regime requires a sufficiently high traffic growth rate to make it financially viable; this does not happen for the other competitive regimes.

Do Planners Get it Right? The Accuracy of Travel Demand Forecasting in Norway

This paper deals with the accuracy of travel demand forecasts among Norwegian road projects. We use data collected from tolled roads and toll free roads. The results reveal that while traffic forecasts of tolled schemes are fairly accurate, traffic forecasts among toll free roads have a higher degree of inaccuracy and are generally underestimated. An explanation for the observed discrepancy between estimated and actual traffic among toll free roads is that road planners may have ignored the existence of induced traffic and that the standard national traffic growth rates used in the transport models has been too low. For tolled roads, an explanation for the higher degree of forecast accuracy is that planners over the years have been scrutinized to provide careful estimates. Our recommendation is that traffic forecasts provided by planners should constantly be subjected to scrutiny by independent consultants before being presented to the decision makers. Aspects that need to be specifically examined include: (1) the extent to which a road project may lead to induced traffic, (2) the extent to which transport models accommodate appropriate factors and, (3) the extent to which forecasts made address uncertainties by providing confidence intervals of estimates.

Pavement Rehabilitation Strategy Selection for Steel Suspension Bridges Based on Probabilistic Life-Cycle Cost Analysis

Field inspections on long-span steel suspension bridges in China reveal that the pavements undergo a fast deterioration process attributed to the flexibility of suspension bridges and the heavy traffic loads. Such extensive damage and enormous repair costs call for a cost-effective rehabilitation strategy for these bridges. In this paper, the pavement rehabilitation strategy is investigated for the Runyang Suspension Bridge in China with the aid of the life-cycle cost analysis (LCCA). Three alternatives are compared for their economic efficiency, and both agency costs and user costs are taken into account. To consider the uncertainties that abound in the LCCA, probabilistic analyses are made in which the Latin hypercube method is used to provide samples of random variables. According to the LCCA results, the user costs are a considerable proportion of the total costs so that the selection of rehabilitation strategies is significantly influenced by the user costs. In this regard, the second alternative, the double-layer pavement (guss asphalt plus stone matrix asphalt) is the most cost-effective rehabilitation strategy for the bridge. Additionally, sensitivity analyses show that the traffic growth rates, the discount rate, the work zone duration, and the delay cost rate for passenger cars are the most sensitive variables in the user costs. The methodologies and approaches introduced herein can be easily implemented by practitioners and would be of benefit to pavement rehabilitations for steel suspension bridges.

The average response time in a heavy-traffic srpt queue

Shortest Remaining Processing Time first (SRPT) has long been known to optimize the queue length distribution and the mean response time (a.k.a. flow time, sojourn time). As such, it has been the focus of a wide body of analysis. However, results about the heavy-traffic behavior of SRPT have only recently started to emerge. In this work, we characterize the growth rate of the mean response time under SRPT in the M/GI/1 system under general job size distributions. Our results illustrate the relationship between the job size tail and the heavy traffic growth rate of mean response time. Further, we show that the heavy traffic growth rate can be used to provide an accurate approximation for mean response time outside of heavy traffic.

Eco-sustainable system and network architectures for future transport networks

Technology analysis indicates that silicon technology evolution will not be able to catch up with future global Internet traffic growth rates. As a result, current network and system designs as wel...

Violation or strengthening of the self-financing doctrine at international airports by SMCP funded PPP schemes?

International airports are among the few examples of transport infrastructures which can well achieve self-financing. The growing interest of private companies in airport construction and operation is the visible testimony to this fact. However, the financing structures of airports are complex, involving not only traffic, passenger and goods handling, but also non-aviation services, such as retail, car parking or intermodal facilities. The integration of social marginal cost pricing schemes into this organizational structure according to the strategic plans of the European Commission, however, is challenging. This paper investigates whether they comply with a second strategic policy objective at European and national level, which is to foster public–private partnerships (PPPs) in transport financing in terms of full cost coverage, risks and incentives. The cases analysed in this paper deal with two sites with very different characteristics: Munich Airport which has been publicly operated since 1991 and the Bulgarian airports Varna and Burgas, which have been managed since 2007 by one concessionaire and whose planning and future development is being accomplished with private capital. The results of both cases showed that self-financing is possible in case congestion costs are considered in the SMCP schemes, and given that air traffic growth rates return to the significant levels prior to the economic crisis. The chapter will discuss the legal implications of congestion pricing at European airports which are violating current EC legislation, as well as the impact of alternative pricing schemes on the environmental performance and technological innovation in aviation.

Highway Project Level Life-Cycle Benefit/Cost Analysis under Certainty, Risk, and Uncertainty: Methodology with Case Study

One of the key steps in the highway investment decision-making process is to conduct project evaluation. The existing project level life-cycle cost analysis approaches for estimating project benefits maintain limited capacity of probabilistic risk assessments of input factors such as highway agency costs, traffic growth rates, and discount rates. However, they do not explicitly address cases where those factors are under uncertainty with no definable probability distributions. This paper introduces an uncertainty-based methodology for highway project level life-cycle benefit/cost analysis that handles certainty, risk, and uncertainty inherited with input factors for the computation. A case study is conducted to assess impacts of risk and uncertainty considerations on estimating project benefits and on network-level project selection. First, data on system preservation and expansion, usage, and candidate projects for state highway programming are used to compute project benefits using deterministic, risk-based, and uncertainty-based analysis approaches, respectively. Then, the three sets of estimated project benefits are implemented in a stochastic optimization model for project selection. Significant differences are revealed with and without uncertainty considerations.

Aviation and global climate change in the 21st century

Aviation emissions contribute to the radiative forcing (RF) of climate. Of importance are emissions of carbon dioxide (CO 2), nitrogen oxides (NO x ), aerosols and their precursors (soot and sulphate), and increased cloudiness in the form of persistent linear contrails and induced-cirrus cloudiness. The recent Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) quantified aviation's RF contribution for 2005 based upon 2000 operations data. Aviation has grown strongly over the past years, despite world-changing events in the early 2000s; the average annual passenger traffic growth rate was 5.3% yr −1 between 2000 and 2007, resulting in an increase of passenger traffic of 38%. Presented here are updated values of aviation RF for 2005 based upon new operations data that show an increase in traffic of 22.5%, fuel use of 8.4% and total aviation RF of 14% (excluding induced-cirrus enhancement) over the period 2000–2005. The lack of physical process models and adequate observational data for aviation-induced cirrus effects limit confidence in quantifying their RF contribution. Total aviation RF (excluding induced cirrus) in 2005 was ∼55 mW m −2 (23–87 mW m −2, 90% likelihood range), which was 3.5% (range 1.3–10%, 90% likelihood range) of total anthropogenic forcing. Including estimates for aviation-induced cirrus RF increases the total aviation RF in 2005–78 mW m −2 (38–139 mW m −2, 90% likelihood range), which represents 4.9% of total anthropogenic forcing (2–14%, 90% likelihood range). Future scenarios of aviation emissions for 2050 that are consistent with IPCC SRES A1 and B2 scenario assumptions have been presented that show an increase of fuel usage by factors of 2.7–3.9 over 2000. Simplified calculations of total aviation RF in 2050 indicate increases by factors of 3.0–4.0 over the 2000 value, representing 4–4.7% of total RF (excluding induced cirrus). An examination of a range of future technological options shows that substantive reductions in aviation fuel usage are possible only with the introduction of radical technologies. Incorporation of aviation into an emissions trading system offers the potential for overall (i.e., beyond the aviation sector) CO 2 emissions reductions. Proposals exist for introduction of such a system at a European level, but no agreement has been reached at a global level.

The potential for European aviation CO 2 emissions reduction through the use of larger jet aircraft

There is increasing pressure to reduce global CO 2 emissions, with aviation targeted as an industry with high future expected growth and limited potential for reduced emissions. In Europe, air transport is likely to be included in the Emissions Trading Scheme from 2012, allowing open trading with other sectors. The proposed scheme may be economically efficient but will it do much towards curbing aviation emissions? A number of papers have looked at the ETS impact on air traffic growth rates, and others have forecast the rate of likely future fuel efficiency gains. This paper examines the potential for greater fuel efficiency through the use of larger aircraft and different patterns of operation. Fuel efficiency was found to be related to aircraft size with more benefit from trading up with short/medium-haul than with long-haul aircraft. This relationship only held for long-haul aircraft if those aircraft with two main decks were removed from the sample (these types showing inherently lower fuel efficiency). Combining these findings with manufacturers' and other forecasts of average aircraft size suggests that less than 1% a year of fuel efficiency gains will be available from this source over the next 20 years.

100 Gigabit-per-second: Ultra-high transmission bitrate for next generation optical transport networks

Abstract Modern telecommunication networks have to provide enormous data transport capacity in order to enable the dramatic annual internet traffic growth rates. As an illustration, today some internet exchange nodes partly exhibit annual peak traffic growth rates of more than 200% due to strongly emerging data and broadband video services. This explosion of internet data and video traffic can only be assured by the implementation of the most advanced optical metro and core transport network technologies. It is likely that next generation telecommunication transport networks will be based on 100 Gigabit/s Ethernet (100 GbE) interconnections. Here we will report on the technical challenges and achievements associated with the development of ultra-high speed components and systems for serial 100 Gbit/s optical transmission. To cite this article: G. Veith et al., C. R. Physique 9 (2008).

The Dependence of Vehicle Emission Profiles on Traffic Growth, Technology Gain, and Fleet Turnover: A Comparative Study and Sensitivity Analysis

In this paper we explore the dependence of vehicle emission profiles over a twenty-five year period on three factors: the rate of traffic growth ( g), the fleet renewal rate (Λ), and the technology ‘gain’ (θ) following a step change in emission standards. Using analytic and numerical methods we determine the conditions relating to g, Λ, and θ which result in three types of emission profile. These consist of: type-I profiles, in which emissions continue to rise but at a reduced rate; type-II profiles which fall, attain a minimum, and subsequently rise from a lower base; and type-Ill profiles which continue to fall over a forecasting period. For all profiles we determine the total reduction in vehicle emissions arising from revised standards, and the sensitivity of the total emissions to changes in their determining factors. Data from the UK are used to illustrate the approach which is extended in a wide range of sensitivity tests to explore differences in emission profiles between advanced industrialised and rapidly developing countries. We show that while it may be necessary for all countries to rely on both technological and behavioural policy instruments to reduce emissions, in advanced industrialised countries it may be more effective to improve emission standards, while, in contrast, moderating the rate of traffic growth may be relatively more effective in the rapidly industrialising world. The profiles resulting from the change in emission standards accompanying the introduction of catalytic converters are used to illustrate the general approach.

Sensitivity of Design Parameters on Optimal Pavement Maintenance Decisions at the Project Level

Sensitivity analyses are important parts of both studying complex systems and measuring the variation in input parameters on the response. They are useful to decision makers for understanding the robustness of the optimal solution that they are to adapt to variations of the parameters of the problem. The sensitivity of the optimal solution of a project-level pavement management problem is analyzed, and the robustness of the optimal solution to the interventions and the timing, cost, and benefit are investigated. The input parameters, which affect the optimal maintenance solution, are identified as the structural and functional condition parameters (defined in terms of deflection and roughness, respectively, at the beginning of the analysis period), traffic volume, growth rate, and discount rate. The problem of computing the optimal treatment and timing for a given budget level is modeled as a mixed integer nonlinear optimization problem and solved by using a computationally efficient network-optimization technique. The benefits are evaluated by considering the pavement performance and are quantified as the area between the performance curve and the threshold values. The optimal budget required for pavements in different structural and functional conditions as well as traffic levels is presented. The effect of initial pavement condition on the optimal maintenance actions as well as their timings is studied. The result of the sensitivity analysis showed that the cumulative standard axle loads and traffic growth rate have a significant effect on the selection and timing of rehabilitation and preventive maintenance actions. The effect of the discount rate on the maintenance management decisions is also presented.