Showing papers on "Traffic count published in 1992"

Roadway seasonal classification using neural networks

Abstract: The parameter average annual daily traffic (AADT) is an important factor used in transportation planning, design, maintenance, and other transportation decision-making processes. The most commonly used approach for obtaining the AADT of a particular roadway facility is to obtain short-term counts (usually 48 h), apply the appropriate seasonal coefficients (also known as seasonal factors), and compute the AADT. In this study, a thorough discussion regarding AADT parameter, seasonal factor, annual traffic pattern, and road attributes related to roadway systems is presented. The existing approaches for determining traffic pattern—cluster analysis and regression analysis–are reviewed. Subsequently, an investigation of the potential applicability of the adaptive resonance theory 1 type of neural network associated with roadway classification and pattern recognition is given. In the comparative-analysis part of this paper, all three methods are applied to the same database, and the results of each method’s performance are presented. Finally, after discussing the results, the conclusion is made that the presented adaptive resonance theory’s performance for the given problem is superior when compared to the conventional methods. Some thoughts for further research in this area are also presented.

Freight demand model estimation from traffic counts

Abstract: This paper presents a freight demand estimation model which uses traffic counts. In this model, the tonnage moved between points per unit of time is represented in the form of an origin destination (O-D) matrix. In the estimation, it is assumed that the commodity movements are represented by a gravity model. Two types of gravity model are used: the GR (Gravity Model) and the GO (Gravity-Opportunity model). In the procedure, the link flows are expressed as a function of the O-D matrix. The parameters of the postulated model are then estimated so that the errors between the estimated and the observed link flows are minimised. Three methods of estimation are demonstrated: a) the Non-Linear- Least- Squares Estimation Method (NLLS), and b) two Maximum- Likelihood Estimation Methods. Two goodness-of-fit (GOF) statistical tests are used to ascertain how well the calibrated model reproduces the observed O-D matrix (the Root Mean Square Error (RMSE) and relative %RMSE, and the Coefficient of determination). An inter city freight movement data survey in Bali Province of Indonesia was used to test these models and estimation methods. In this the freight was classified into 5 commodity groups. There were no traffic counts available, but 30 were generated by loading the observed matrices onto the network using all or nothing asignment. Conclusions are provided about the best model to use in Bali, the relative accuracy of the models and what parameters this depends upon, and the number of traffic counts required. For the covering abstract of the publication see IRRD 850746.

Layout and design factors affecting cycle safety at t-junctions

Abstract: This paper describes an investigation of cyclists' safety at priority- controlled T-junctions, which account for a significant proportion of injury accidents to cyclists. Previous classification studies have identified six main types of junction-related accidents. About 30% of cycling injury accidents at T-junctions involve a motor vehicle, emerging from a minor road, conflicting with a cyclist on the major road. In the present study, accident and control sites were identified and then surveyed. Information was collected about: (1) junction geometry and layout; (2) traffic count data; (3) driver behaviour. Seven differences in geometry were found between accident and control groups, of which the most significant concerned the wider entry of the minor arm at the accident sites. Accident sites were generally found to have more traffic, especially from the minor road. Visibility from the minor road to its right side was significantly better at accident sites. The authors recommend that a review of entry treatments be made, with a view to identifying appropriate measures to be applied at junctions with high main-road cycle flows expected. It is possible that good visibility at junctions should be accompanied by traffic calming or speed reduction measures on entry. Behaviour of drivers entering from a minor road could affect accident potential.

Impact of changes in vehicle weight legislation on pavements in alberta, canada

Abstract: In 1988 the Canadian Council of Ministers of Transportation under the Roads and Transportation Association of Canada (RTAC now TAC) made recommendations for a common set of truck weight and dimension limits on highway pavements in Canada. This effort was aimed at ensuring uniform interprovincial regulations in order to improve the efficiency of the trucking industry. The changes were implemented in Alberta in 1988. One-year "before" and "after" data from an instrumented traffic counting and weigh-in- motion site on a major 4-lane rural arterial highway in Alberta were used to investigate the impact of increased axle weight limits and different axle configurations on the pavement structure. This paper describes the data set-up, analytical process used and illustrates the severity of the impact on pavements using a design example. The analysis indicates that the one-directional average daily traffic increased some 12%, from 13,000 vehicles/day in 1986 to 14,600 in 1989. Although the percentage of trucks only increased from 10 to 11.8%, the equivalent single axle loads (ESALs), were almost 70% higher. Based on these data, it appears that the impact of the changes in trucking regulations is significant. (A) For the covering abstract of the conference see IRRD 852196.

The use of a capacitative mat for dynamic weighing of vehicles in normal traffic

Abstract: A methodology was developed for the analysis of dynamic road loads using a capacitive weigh-in-motion mat with two inductive loops installed on the road surface in less than 25 min The dynamic impact caused by this obstacle was assessed by means of a theoretical model Load spectra were found per type of road The possible effects of decisions as to vehicle weights and dimensions on traffic aggressivity were demonstrated They are not always as intended (A) For the covering abstract of the conference see IRRD 852196

Truck behaviour on highway facilities

Abstract: The recent availability of weigh-in-motion (WIM) traffic monitoring data is exploited for the purpose of investigating safety-related truck behaviour on highway facilities. This paper briefly describes WIM technology and its capabilities to generate traffic monitoring data which are important for traffic safety analysis. The body of the paper provides examples of data analysis that demonstrate the usefulness of WIM data for investigating safety-related truck behaviour. The examples include determination of truck exposure rates, and evaluation of vehicle speed and headway distributions as a function of truck type and truck load. (A) For the covering abstract of the conference see IRRD 852196.

A survey of traffic monitoring and surveillance in the los angeles area

Abstract: Large metropolitan areas wrestle daily with the problem of accommodating a vehicle population that exceeds the capacity of portions of the road network. When the vehicle demand exceeds the capacity of the roadway, the resulting congestion produces low travel speeds, erratic stop-and-go driving on freeways, unpredictable travel times, increased operating costs, higher accident frequencies, and increased environmental damage. The Los Angeles region has a well earned reputation for the worst traffic congestion and air quality in the United States. A wide range of traffic management and congestion management techniques are being employed by the various state, county and city agencies in the Los Angeles region. These public agencies continue to develop monitoring and control systems that range from the extensive monitoring systems for the freeways and major urban corridors to small scale systems monitoring just a few problem intersections. This paper presents a survey of the various traffic congestion monitoring systems in use within the Los Angeles Metropolitan area. The paper describes a wide range of surveillance and control technologies from the simple to the complex. Items discussed include approximate cost of installation and operation, the potential effectiveness of the systems, and the approximate applications. (A) For the covering entry of this conference, see IRRD abstract no. 843369.

Surveying traffic delays at a roundabout near plymouth

Abstract: Traffic delay models can be no more accurate than the data on which they are based. This paper attempts to highlight some of the problems of site data collection experienced in a survey of traffic delays at a roundabout near Plymouth. Data quality of the level required for high level definition modelling of roundabouts may not always be available at reasonable costs, placing constraints on the practical range of modelling techniques which may legitimately be attempted. Surveys of observed vehicle delays are discussed concentrating on problems of estimating peak flows, vehicle composition, occupancy and queue length. Physical overloading of enumerators involved a reduction in the number of vehicle categories which could be recorded, and a need to sample only one minute in each five minute period. Problems of observing 4 lanes of vehicles, often in low sun, rain or spray conditions, often in waves are noted. The inadequacy of alternative procedures such as video or tape recording of number plates at exits up to 300 metres distant is also highlighted. The need to be able to model the effects of traffic at roundabouts, and possibly present results including the moments of delay distributions is one which may challenge modellers in the future. (A) For the covering abstract of the conference see IRRD 851540.

Value of a sharp traffic analysis for highway companies: the experience of saprr

Abstract: This article describes the HESTIA traffic analysis station developed by the Electronique Control Company as part of the French "Weighing in Motion" research project. This provides real time information about traffic compositions, speeds, and flows. There are two piezo electric sensors and one induction traffic loop per traffic lane as well as an intelligent detector which analyses the data collected by the sensors. The following data are obtained for each vehicle: passage time; speed; classification; the weight of each axle; total weight; distance between each axle; vehicle length; and time since the preceding vehicle. Data are sent to the central control unit which can produce a range of statistical reports. These can be displayed in a number of graphical formats, including graphs and histograms. Examples provided include the distribution of number of axles by vehicle weight class; speeding by time of day (or hour) by specific classes of vehicle; and monthly distribution of heavy goods vehicles. Measurement accuracy has been found to be high, as is the repeatability. For the covering abstract of the conference see IRRD 852196.

Ccats: image processing-based traffic sensor

Abstract: The method of operation of a CCATS (camera and computer-aided traffic sensor) system is outlined. CCATS is based on an image window approach in which conventional traffic parameters are derived for a maximum of three separate lanes. The sensor has the intelligence to detect definable traffic situations based on the programmable combinations of all the measured parameters and is able to control variable message signs. Applications of CCATS are described and include statistical data collection, automatic queue detection, automatic incident detection and a traffic monitoring extension for CCTV surveillance systems. In the development of CCATS the involvement of the potential user has been particularly important in design. An evaluation of cost benefits in Belgium has proved favourable. For the covering abstract of the conference see IRRD 854422.