Changes In Traffic Flow Research Articles

Combining kohonen maps with arima time series models to forecast traffic flow

A hybrid method of short-term traffic forecasting is introduced; the KARIMA method. The technique uses a Kohonen self-organizing map as an initial classifier; each class has an individually tuned ARIMA model associated with it. Using a Kohonen map which is hexagonal in layout eases the problem of defining the classes. The explicit separation of the tasks of classification and functional approximation greatly improves forecasting performance compared to either a single ARIMA model or a backpropagation neural network. The model is demonstrated by producing forecasts of traffic flow, at horizons of half an hour and an hour, for a French motorway. Performance is similar to that exhibited by other layered models, but the number of classes needed is much smaller (typically between two and four). Because the number of classes is small, it is concluded that the algorithm could be easily retrained in order to track long-term changes in traffic flow and should also prove to be readily transferrable.

The impact of political changes on transport in Central and Eastern Europe

Major political transformations in Central and Eastern Europe exert substantial changes in transport. The results may be seen in: changes of structure of transported goods (less minerals and heavy products, more processed consumer goods); changes in traffic flows (less trade within Eastern Europe, more with Western states); changes in the means of transport (decrease of railway transport, very rapid increase of motor car transport and private car ownership); changes in human behaviour (more international travel, less subsidized commuting and inland travel); and changes in the ownership of transport companies (decrease of state sector, creation of private firms).

A fundamental consideration on evaluating noise produced by road traffic controlled by traffic signals

The actual road traffic noise that we encounter is affected by traffic signals. So, the random noise fluctuations usually exhibit periodic nonstationary properties caused by the periodic temporal change of traffic flow. Also, statistical parameters such as the equivalent sound level ( L eq) and the median value of sound level ( L 50) are important for noise evaluation and regulation problems. In this paper, a new approximate probability density function (pdf) of nonstationary noise level fluctuation is proposed in a case where the road traffic flow is controlled by traffic signals, by paying special attention to the periodicity of fluctuation patterns of the cumulant statistics of noise level. Next, the explicit expressions of L eq and L 50 are derived as an application of the above theory. The effects of the nonstationary properties caused by the traffic signals on the noise evaluation indices, L eq and L 50, are shown quantitatively. Finally, statistical evaluation methods for the dispersion of L eq and L 50 estimations caused by the finiteness of the sample sizes are theoretically considered, in a case when L eq and L 50 for the periodic nonstationary road traffic noise are experimentally estimated by using the usual sound level meter and sampling method.

Safety effects of 30 km/h zones in the Netherlands

Since 1983, Dutch municipal authorities can institute a maximum speed of 30 km/h on roads or in zones within built-up areas. The safety effects of 30 km/h zones are supposed to be positive. In order to be sure about this, the Ministry of Transport has stimulated 15 municipalities to implement a 30 km/h zone and set up an evaluation of the safety effects of these zones. The evaluation research is coordinated by the Institute for Road Safety Research (SWOV). The evaluation concerns the changes in traffic flows, opinions of residents, conflicts, and accidents. This paper gives the results of the evaluation.

Planning and design of passing lanes for the Trans-Canada Highway in Yoho National Park

This paper describes the techniques used in the planning and design of a system of passing lanes for the Trans-Canada Highway in Yoho National Park. The techniques, which include a traffic simulation model, were developed to allow the evaluation of the impact of low-cost operational improvements such as passing lanes on the level of service. The traffic simulation model allowed the investigation of a wide range of highway alternatives in addition to changes in traffic flow, traffic stream characteristics, and vehicle performance characteristics. The passing lane designs described in the paper are based on the concept of incorporating passing lanes within the existing highway cross section. The design concept has evolved from the experimental passing lane project in Banff. In addition to geometric design, signing, and road marking guidelines, warrants for bicycle lanes on the Trans-Canada Highway are also presented. Key words: highway planning and engineering, two-lane highways, traffic simulation model, level of service, passing lanes, Trans-Canada Highway.

A prediction method of non-stationary road traffic noise based on fluctuation patterns of an average number of flowing vehicles

The actual road traffic noise which is encountered in daily life usually shows non-stationary fluctuation patterns caused by the temporal change of traffic flow. Also, statistical parameters such as the median value of the sound level, L x, as well as the lower order statistical values of the sound energy or level, are important for noise evaluation and regulation problems. In this paper, a statistical theory for the probability density function (pdf) of non-stationary noise level fluctuation is proposed in a case where the road traffic flow is controlled by traffic signals, by paying special attention to the periodicity of fluctuation patterns of the statistics of the noise level and the number of flowing vehicles. Next, a new practical trial of the statistical prediction for the pdf of non-stationary road traffic noise is considered. The experimental results of applying this in a trial to the actual noise data are in full agreement with the theory.

Long Term Prediction of Traffic Flow

Prediction of traffic flow is now becoming a basic problem in designing variable information boards or route guidance (route telling) systems in road networks. Although, time series analysis is widely applied to this problem, it is known that the error of prediction increases rapidly as the prediction lead time increases and it is difficult to decrease the delay of the predictor as long as the methods based on time series analysis are used. In this paper, a new method defined by the combination of autoregressive model fitting and pattern matching, is proposed. It uses the features extracted from historical data of traffic flow to compensate the delay caused by the predictor itself and also real time data are combined in the form of autoregression to trace the sudden changes of traffic flow.

The Effects of Traffic Flow on Residential Property Values

Abstract This article presents an empirical study of the effects of traffic flow on residential property values in the community of Grand Rapids, Michigan. Residential values in two identical neighborhoods are compared over a twenty-five year period. One neighborhood serves as a control for the measurement of the impact of changes in traffic flow upon residential values in the other. The results show that residential property values exhibit a surprisingly high elasticity with respect to reductions in traffic flow. The policy implications of these findings for cities laid out in a gridiron street pattern are explored.

I—The Development of the Specification

Every day several hundred subsonic aircraft travel between the European and North American continents. Because of noise limitations at major airports, aircraft turn-around times and the time difference between the continents, the direction of the main traffic flow changes through the day. In the afternoon (GMT) the flow is predominantly westbound, while in the early hours of the morning the flow is predominantly eastbound. Oceanic air traffic control for the North Atlantic region has evolved into what is now known as the Organized Track System; traffic is divided into streams, each stream flying at a specified set of flight levels on one of several adjacent tracks. Figure 1 shows an example of the subsonic track system during the westbound peak. To secure operating economy the layout of the track system on any day is matched to the pattern of the upper winds.

The energy crisis, characteristics of traffic flows, and highway safety

The impact of changes in traffic flow upon accident frequency and severity as represented by mean speed and standard deviation of speeds was investigated in terms of effects observed during the energy crisis of 1973–1974. Based upon empirically reported results which related accident rate to deviation from mean speed and accident severity to speed at the time of accident, accident rates were predicted as function of highway types and flow characteristics. These relationships were used to investigate the effect of observed changes in traffic flows upon accident rates for the state of Wisconsin. Apparently as much of the improvement in accident conditions observed stemmed from changes in the standard deviation of the vehicle speeds as from the reduction in mean speed.

Statistical-Physical Models of Urban Radio-Noise Environments - Part I: Foundations

Theoretical foundations for an analytical model of urban radio-noise environments are presented at a level of generality broad enough to include the pertinent physical and statistical elements which critically influence the temporal and statistical character of such interference in radio receivers. The central roles of geometry, directionality (beam patterns), waveforms (from the interfering sources), motion (Doppler), source density and distribution, and secular variations of source parameters, as well as the radiation mechanism, are specifically developed. The basic statistical model (BSM) involves independent sources, in space (and in time), leading to Poisson radiation fields and a Poisson process X(t) in a typical receiver. This received process X(t) can be considered the sum of a Gauss process (by the central limit theorem) representing the cumulative effects of a large number of sources, none of which is very large vis-a-vis the rest, and a Poisson process produced by those few strong transients which when present dominate the background. The process X(t) is essentially stationary for periods comparable to the secular period of changes in traffic intensity and flow, which permits the construction of usefully large experimental ensembles from which to estimate the process statistics. A semiempirical, but more analytically tractable model similar to that introduced by Hall [6] for impulsive atmospheric noise but used here for independent sources is also constructed. This model is represented by X(t) = a(t) Z(t), where a,Z are independent processes, both zero mean, and Z is regarded as Gaussian.