Traffic Volume Variation Research Articles

Heterogeneous Traffic Induced Effects on Vertical Dispersion Parameter in the Near Field of Roadways - a Wind Tunnel Study

The varying traffic parameters such as traffic volume, speed, shape and size, and terrain roughness conditions play a vital role on dispersion of pollutants in the near field of roadways. Simulation experiments were carried out in the Environmental Wind Tunnel (EWT) to evaluate the traffic induced effects on vertical dispersion parameter (σ z ) for heterogeneous traffic conditions in the near field of roadways for evaluating the effect of variations in traffic volume, terrain roughness condition and approaching wind direction. The model vehicle movement system was fabricated and made operational in the EWT, which allowed the variation in traffic volume, speed and wind road inclination. Sixty-six hydrocarbon tracer experiments were performed to evaluate σ z in the near field of roadways for variable traffic volume, three terrain roughness conditions and two approaching wind directions (i.e., 90° and 60°). The values of σ z for heterogeneous traffic conditions were found to be higher for low roughness conditions in comparison to other two higher roughness conditions for various traffic volumes and approaching wind directions.

Traffic-adaptive aggregate channel allocation for future cellular communication systems

A fundamental problem in third-generation mobile systems is the adaptation of the channel allocation to the traffic volume variation. Traffic adaptation may be partly achieved by the following (aggregate channel allocation) problem: given the set of channels, the cell structure and the load to be accommodated in each cell within a certain time zone, find the optimal allocation of channels to cells subject to the restrictions arising from the minimum permissible distance of cells where the same channel can be used at the same time. In this paper the problem is optimally formulated and efficiently solved by a heuristic. In the sequel the performance of a combined channel management scheme that uses the above problem for handling major traffic variations and a distributed DCA scheme for handling local traffic variations is assessed. Finally, results are presented and some concluding remarks are made. © 1998 John Wiley & Sons, Ltd.

Traffic‐adaptive aggregate channel allocation for future cellular communication systems

A fundamental problem in third-generation mobile systems is the adaptation of the channel allocation to the traffic volume variation. Traffic adaptation may be partly achieved by the following (aggregate channel allocation) problem: given the set of channels, the cell structure and the load to be accommodated in each cell within a certain time zone, find the optimal allocation of channels to cells subject to the restrictions arising from the minimum permissible distance of cells where the same channel can be used at the same time. In this paper the problem is optimally formulated and efficiently solved by a heuristic. In the sequel the performance of a combined channel management scheme that uses the above problem for handling major traffic variations and a distributed DCA scheme for handling local traffic variations is assessed. Finally, results are presented and some concluding remarks are made. © 1998 John Wiley & Sons, Ltd.

Modeling Conflicts of Heterogeneous Traffic at Urban Uncontrolled Intersections

The behavior of traffic in the heterogeneous environment of an urban uncontrolled intersection is complex and difficult to model. The present study describes the methodology of simulating the traffic flow and thereby estimating the number of conflicts in varying traffic flow conditions. The arrival pattern of vehicles was represented by a multivariate distribution to generate input to the simulation model. The model was validated externally, using field observed data, and was found to predict the number of conflicts well. As an illustration of usefulness of the model, variation of conflict rate (the probability of a vehicle's getting involved in conflict) due to variation in traffic volume and the proportion of right-turning traffic has been quantified. Under the prevailing traffic composition and turning movements, the conflict rate is estimated to lie in the range of 0.66–0.70, 0.79–0.84, and 0.80–0.87 for intersection volumes of 2,000, 2,500, and 3,000 vehicles per hour, respectively. Issues related to the applicability of the proposed model are briefly discussed.

Using Seasonal and Day-of-Week Factoring to Improve Estimates of Truck Vehicle Miles Traveled

Procedures developed by FHWA for short-duration traffic counts for seasonal and day-of-week variations in traffic volumes are capable of producing estimates of annual average daily traffic (AADT) that are quite accurate. Moreover, there is virtually no bias in these estimates, so AADT estimates for a set of road sections can be used to produce unbiased estimates of total vehicle miles traveled (VMT) for systems of roads. Unfortunately, corresponding procedures are not generally used for estimating AADT by vehicle class, and the less sophisticated procedures that are commonly used contribute to substantial overestimates of truck AADT and VMT. Current procedures apparently overestimate VMT by 25 to 40 percent for combination trucks and possibly more for single-unit trucks. Modified versions of the FHWA factoring procedure that are capable of producing substantially improved estimates of truck VMT and of AADT of combination trucks are presented. These procedures use seasonal and day-of-week facto...

Measurement of Truck Load on Bridges in Detroit, Michigan, Area

The objective of the study was to determine the actual truck loads on selected bridges in the Detroit, Michigan, area. Seven representative bridges were selected. The measurements were taken by using a weigh-in-motion system. For each measured truck, the record included vehicle speed, axle spacing, and axle loads. The variation in the accuracy of the gross vehicle weight (GVW) measurement was estimated to be ±5 percent and that of the axle weights was estimated to be ±20 percent for most types of trucks. Selected bridges were instrumented, and measurements were taken for 2 or 3 consecutive days. There was a considerable variation in traffic volumes and the weights of trucks, even within a given geographic area. The estimated average daily truck traffic varied from 500 to 1,500 in one direction. The maximum observed truck weights varied from 360 kN (81 kip) to 1100 kN (250 kip). The maximum observed axle weights varied from 90 kN (20 kip) to 225 kN (50 kip). The percentage of trucks exceeding the legal limits in Michigan varied depending on the road. The heaviest GVWs and axle weights were observed on Interstate highways. The largest percentage of overloaded trucks was observed for 11-axle vehicles. The maximum lane moments and shears from the trucks varied between 0.6 and 2.0 times AASHTO load and resistance factor design values. It was found that there are similarities in GVW and lane moment distributions.

Using Seasonal and Day-of-Week Factoring to Improve Estimates of Truck Vehicle Miles Traveled

Procedures developed by FHWA for “factoring” short-duration traffic counts for seasonal and day-of-week variations in traffic volumes are capable of producing estimates of annual average daily traffic (AADT) that are quite accurate. Moreover, there is virtually no bias in these estimates, so AADT estimates for a set of road sections can be used to produce unbiased estimates of total vehicle miles traveled (VMT) for systems of roads. Unfortunately, corresponding procedures are not generally used for estimating AADT by vehicle class, and the less sophisticated procedures that are commonly used contribute to substantial overestimates of truck AADT and VMT. Current procedures apparently overestimate VMT by 25 to 40 percent for combination trucks and possibly more for single-unit trucks. Modified versions of the FHWA factoring procedure that are capable of producing substantially improved estimates of truck VMT and of AADT of combination trucks are presented. These procedures use seasonal and day-of-week factoring to reduce the errors in truck AADT estimates and to eliminate the upward bias in truck VMT estimates that result from the use of unfactored weekday classification counts.

Measurement of Truck Load on Bridges in Detroit, Michigan, Area

The objective of the study was to determine the actual truck loads on selected bridges in the Detroit, Michigan, area. Seven representative bridges were selected. The measurements were taken by using a weighin-motion system. For each measured truck, the record included vehicle speed, axle spacing, and axle loads. The variation in the accuracy of the gross vehicle weight (GVW) measurement was estimated to be ±5 percent and that of the axle weights was estimated to be ±20 percent for most types of trucks. Selected bridges were instrumented, and measurements were taken for 2 or 3 consecutive days. There was a considerable variation in traffic volumes and the weights of trucks, even within a given geographic area. The estimated average daily truck traffic varied from 500 to 1,500 in one direction. The maximum observed truck weights varied from 360 kN (81 kip) to 1100 kN (250 kip). The maximum observed axle weights varied from 90 kN (20 kip) to 225 kN (50 kip). The percentage of trucks exceeding the legal limi...

Child pedestrian deaths: sensitivity to traffic volume--evidence from the USA.

In case centred epidemiological studies, traffic volume has been shown to be a potent risk factor for child pedestrian injuries. Nevertheless, over the past two decades child pedestrian death rates have fallen in many countries despite large increases in traffic volumes, suggesting that other factors are responsible for the long term decline in death rates. This study aimed to investigate the relationship between short term changes in traffic volume and child pedestrian death rates. The relationship between child pedestrian death rates and traffic volume in the USA for the period 1970-88 was investigated. Trends in death rates and in traffic volume were removed by the time series method of differencing. After removing the long term trends, there was a close relationship between the year to year variation in traffic volume and the year to year variation in the child pedestrian death rate. Most notably, in the two periods when traffic volume actually fell, the falls in the child pedestrian death rate were considerably larger than those seen at any other time. Overall, decelerations in the rate of increase in traffic volume were accompanied by accelerations in the rate of decline in the child pedestrian death rate. While other factors may determine long term trends in child pedestrian death rates, they are very sensitive to short term changes in traffic volume. Public policy changes which limit the growth in traffic volume have the potential to accelerate the decline in child pedestrian death rates.

Temperature fields and air pollution build-up over the Athens basin

The wind and temperature fields, and the associated vehicle-induced atmospheric pollution build-up over the Athens Basin have been simulated using a time-dependent, three-dimensional numerical model. The model utilizes the continuity equation to produce a non-divergent wind field adopting a mass consistent methodology; then the heat conseration equation is solved, while a two-equation (k-ϵ) turbulence model is used for obtaining the turbulent exchange coefficients. Finally the concentration equation is numerically solved in transformed space and the passive contaminants distribution over the Athens complex topography is obtained. The model has been used to predict the temperature distribution and the surface concentrations of pollutants over the Athens area for South wind and a certain traffic scenario during a 24-hour cycle. The obtained results reproduced successfully the diurnal variation of the atmospheric stability conditions; the variation of the resulting surface temperature agreed well with available measurements, while the results for the atmospheric pollution showed that the banning of the car traffic in the city-center is effective only for certain time periods within the day, and that in the early afternoon hours the traffic could be allowed without any harmful effects to the air quality of the city as at time this unstable atmospheric conditions prevail. Also the use of the model revealed that the daily variation of the CO concentration can be mainly attributed to the atmospheric stability changes during the day rather than to traffic volume variations.

Traffic source emission and street level air pollution in urban areas of Guangzhou, South China (P.R.C.)

Street level air pollution due to traffic emission is a cause of concern in Guangzhou City. During the winter and summer of 1988, the traffic-related air pollutant concentrations, wind field, traffic volume and vehicle speed were measured extensively in three types of street canyons in Guangzhou City. Various types of motor vehicle emission in idle condition were measured and the composite emission factors of vehicles were derived. The variation of traffic volume and vehicle speed in 223 mainstreets were also investigated. The annual air pollutant concentration levels of traffic source emission were calculated. Using CO as a traffic emission tracer for air pollution on the street, the contributions of traffic emission to street level air pollution were determined by the receptor method. Ground level air pollution in Guangzhou has changed from coal combustion emission type into traffic source emission type. The average contributions of traffic source emission to the concentration of CO and NO x on the street in 1988 are about 87% and 67%. The most significant pollutant of ambient air quality that traffic source emission influences in NO x.

Feedback Control of Traffic Congestion Lengths at 2-adjacent Signalized Intersections

This paper presents the feedback control method of traffic congestion lengths at 2-adjacent signalized intersections from system- and control-theoretic viewpoints. Traffic volumes are treated as random sequences, and the traffic volume variation on time is formulated by linear time-varying discrete-time system, The traffic volume balance at each signalized intersection is formulated, and the mechanism for the occurrence, continuation and disappearance of traffic congestion is explained quantitatively. The prediction method of traffic congestion is presented based on the prediction of incoming traffic volumes and flowing out ones. Next, the feedback control method of traffic congestion length, which aimes to hold the traffic congestion length within the permitted queueing length, is proposed. Finally, from the computer simulation results of Route 2 national main road in Fukuyama city, it is confirmed that the feedback control method of traffic congestion lengths at 2-adjacent signalized intersections proposed here is actually effective.

Urban residential location and the comparative statics of traffic congestion

The early land use models tended to ignore externalities associated with urban transportation. More recently, even the models which treat transportation-related externalities analyze the spatial impacts of congestion or pollution mostly numerically by using simulation techniques. This paper theoretically formulates a residential location model which includes congestion and analyzes the comparative statics impacts of variations in traffic volume and road capacity, which are two elements of congestion. The results of comparative static analysis show that a traffic increase will compact the urban form, while provision of more highway capacity induces urban sprawl.

Predicted and measured concentrations of traffic carbon monoxide over Delhi

Carbon monoxide concentration due to vehicular traffic in urban Delhi has been computed by using an analytical dispersion model (IITCO), Pollution Episodic Model (PEM) and Intersection Midblock Model (IMM). While IITCO has been developed in IIT, the other two are operational models in the U.S.A. Computations from models are compared with observations collected at ITO, Janpath, Nazafgarh and Townhall. On-site measurements of CO are taken by using real time analyzers and meteorological parameters are obtained from a micrometeorological tower at IIT Delhi. The model results compare well with observations. The performance of IITCO is compared with PEM and IMM and found to be quite satisfactory. The diurnal variation of concentration is also found to be in good agreement with the diurnal variation of traffic volume.

SOME CHARACTERISTIC FEATURES OF “KIHANSEN” (STEAM-AND-SAIL BOAT) TRAFFIC IN THE SETO INLAND SEA

Even today when land traffic has attained remarkable progress, marine traffic in the Seto Inland Sea is still of high economic value. In fact, “Kihansen” takes up more than half of the total volume of goods transported and is playing an important role in the economic development of that area. It is rather difficult, however, to grasp the actual entity of this business, because over 90% of the shipowners are working on so small a scale that we might say ‘one ship one owner’. And yet in view of its being an important and complicated business, there are many interesting problems to be surveyed in regard to the forms of traffic and management. In this draft, the economic value of the “Kihansen” traffic has been closely studied, by analysing quantitatively the real conditions of fright transport, and through the subsequent regional differences in the degrees of dependence on “Kihansen”, the establishment of the area of operations of traffic, the ways of connection of these area of operations, and through their graphic representation. The following is the gist of the investigation. (1) The “Kihansen” service enjoys some strong points over that of steamships such as adaptability to the traffic conditions of the Inland Sea, reduction of the expenses of loading and unloading, comparative cheapness of short distance freightage, handling chiefly of small cargoes, lack of modernized harbour facilities for steamship, and all this gives the “Kihansen” service the principal position in the Inland Sea traffic. Thus it makes itself one of the fundamental factors in the establishment of the industrial area along the Inland Sea coast. (2) The transported goods being mainly rough and raw materials, the traffic takes the form of one way transport on the whole, while the kinds of goods make a difference in carrying distances, and such goods as coal, metals, fertilizers belong to the long distance transport. (3) While the “Kihansen” traffic in the Seto Inland Sea constitutes a big traffic area of operations centering on the Hanshin (Osaka-Kobe) area, the whole sea may be re-divided into five big traffic areas of operations by regional variations in traffic volume arising from the extent of local industrialization and sectional differences in the kinds and quantities of resources. (4) Namely, they are divided by three north-south lines, Katakami-Naruto line, Fukuyama-Tomo line, Iwakuni-Nagahama line and by two east-west lines, one passing south of Nakashima, Osaki-shimo-jima, Omi-shima, Ikuguchi-shima, Inno-shima, and Kitaki-shima, the other passing north of Nao-shima, and Shodo-shima (Fig.8). (5) As for traffic volume, that within the area of operations is relatively larger. The volume is sweepingly great in the Hanshin (eastern) area, the western area coming next. Aki and Bittyu (northern two) areas are reversely prominent in out-of-the-area-of-operations traffic, but the volume is rather small. The Shikoku (southern) area keeps the balance. The out-of-the-area-of-operations traffic is carried out between the Hanshin area and the western and the Shikoku areas. (6) The main routes of the traffic take this form: raw materials and fuel goods from Northern Kyushu and Shikoku flow into the Hanshin area, and the primary or finished products worked and manufactured there are again distributed among the different parts of the same area of operations. (7) The traffic form can be divided into two big types; one is the external traffic whose object is chiefly to transport rough and raw materials, fuel, and consumer products; the other is the internal traffic shipping various productive and manufactured goods, either primary or finished, to shorter distances, and the principal lies in the latter.