Traffic Flow Volume Research Articles

Integrated model for traffic flow forecasting under rainy conditions

SummaryInclement weather, such as heavy rain, significantly affects road traffic flow operation, which may cause severe congestion in road networks in cities. This study investigates the effect of inclement weather, such as rain events, on traffic flow and proposes an integrated model for traffic flow parameter forecasting during such events. First, an analysis of historical observation data indicates that the forecasting error of traffic flow volume has a significant linear correlation with mean precipitation, and thus, forecasting accuracy can be considerably improved by applying this linear correlation to correct forecasting values. An integrated online precipitation‐correction model was proposed for traffic flow volume forecasting based on these findings. We preprocessed precipitation data transformation and used outlier detection techniques to improve the efficiency of the model. Finally, an integrated forecasting model was designed through data fusion methods based on the four basic forecasting models and the proposed online precipitation‐correction model. Results of the model validation with the field data set show that the designed model is better than the other models in terms of overall accuracy throughout the day and under precipitation. However, the designed model is not always ideal under heavy rain conditions. Copyright © 2016 John Wiley & Sons, Ltd.

Layout Improvement Study to Reduce Staff Walking Distance in a Large Health Care Facility: How to Not Walk an Extra 4740 Miles.

Inefficient facility layouts have been found to be a challenge in health care, with excessive walking adding to the demands of staff and creating delays, which can impact the quality of care. Minimizing unnecessary transportation during care delivery improves efficiency, reduces delays, and frees up resources for use on value-added activities. This article presents a methodology and application of facility design to improve responsiveness and efficiency at a large hospital. The approach described provides the opportunity to improve existing layouts in facilities in which the floor plan is already defined, but there is some flexibility to relocate key areas. The existing physical constraints and work flows are studied and taken into consideration, and the volume of traffic flow throughout the facility guides the decision of where to relocate areas for maximum efficiency. Details on the steps followed and general recommendations to perform the necessary process and data analyses are provided. We achieved a 34.8% reduction in distance walked (4740 miles saved per year) and a 30% reduction in floors traveled in elevators (344 931 floors, which translate to 842 hours spent using elevators) by relocating 4 areas in which frequently used resources are housed.

A hybrid traffic flow model with considering the influence of adaptive cruise control vehicles and on-ramps

Recently, autonomous vehicles and the relevant studies have attracted much attention. Adaptive cruise control (ACC), which is a kind of cruise control system for vehicles, automatically adjusts the vehicle speed to maintain a safe distance from vehicles ahead. Since the vehicle with ACC (called ACC vehicles) is semi-autonomous, the performance of ACC vehicle must be quite different from that of manual vehicle. The characteristics of traffic flow with ACC vehicles should be carefully investigated, especially when the traffic system is a bit complicated, such as on-ramp system. The primary objective of this paper is to propose a traffic flow model to simulate the traffic flow with considering the influence of ACC vehicles and on-ramps. Based on the model proposed by Yuan in 2009 [Yuan Y M 2009 Ph. D. Dissertation (Hefei: University of Science and Technology of China)], a hybrid traffic flow model with considering the influence of ACC vehicles and on-ramps is developed. Considering the differences between ACC and manual vehicles, a car-following sub-model based on constant time headway principle is developed for ACC vehicles, while an MCD cellular automata sub-model is proposed for manual vehicles. Besides, a new parameter, , is introduced to show different psychologies of drivers when changing lane from on-ramp to main road. The lane-changing model for vehicles on-ramp is developed as well. At the end, numerical simulation is demonstrated to study the influence of ACC vehicles on traffic flow at on-ramp, and to reveal the influence of parameters on the proposed hybrid model (i.e., the length of merge area, the desired time headway of ACC vehicle and ) on model performance. The results of this paper are as follows. 1) When the ACC vehicles exist in a traffic system, the performance of traffic flow in a on-ramp area is improved: the influence of merged vehicles on main road is reduced, and the average speed and volume are increased. 2) The increase of ACC vehicles can help to alleviate traffic congestion in both congestion duration and scope aspects. 3) The newly proposed hybrid model is sensitive to the length of merge area lw, the desired time headway of ACC vehicle Hd and lane-changing psychology parameter : the decrease of Hd and the increase of can both improve the average speed and volume of traffic flow. In addition, when the volume of on-ramp is small, the speed and volume of main road can be improved by enlarging lw. When the volume of on-ramp is large, a small lw will be better for traffic flow.

Simulation of Traffic Flows on the Road Network of Urban Area

This paper represents some investigation of models, criteria and methods of estimation of current traffic conditions on urban network. These data have been used for studying of reliability parameters of traffic flow for specific urban transport situations at deriving the information from traffic detectors and probe vehicles. Relationships between trip time, stop time, volume of traffic flow, occupancy and capacity have been obtained.

Software Solution for Planning and Conducting a Transport Survey

In cases when there is no ability to use different intrusive methods for the counting of traffic volume usually a non-intrusive method is used – manual observation using tally sheets. This method of data collection has the following drawbacks: expenses for the decoding of handwritten symbols from the tally sheets; expenses for data input into the database; observers can be irresponsible, etc. In the article a software solution which helps to solve some of the mentioned drawbacks is presented. The requirements for the software solution and software's architecture are presented. The solution consists of three main components: 1) web application – space for project manager for a project configuration, managing observation areas, observers and data exporting; 2) mobile application – application from which an observer can send data about traffic flow volume the system; 3) API – application program interface for communication between the mobile application and the server. The software solution has been implemented and tested for a real problem solution. The paper presents the results of testing, the advantages/disadvantages of the offered solution and directions of future development.

On Missing Traffic Data Imputation Based on Fuzzy C-Means Method by Considering Spatial–Temporal Correlation

The lack of some traffic flow data seriously affects the quality of data collection and analysis in the traffic system. Completing the missing data is one of the most important steps in achieving the functions of intelligent transportation systems. In this paper an approach based on fuzzy C-means (FCM) imputes missing traffic volume data in loop detectors. With spatial–temporal correlation between detectors, the conventional vector-based data structure is first transformed into a matrix-based data pattern. Then, the genetic algorithm is applied to optimize the parameters of cluster size and weighting factor in the FCM model. Finally, the actual traffic flow volume collected at different locations is designed as a testing data set, and two indicators including root mean square error and relative accuracy are used to evaluate the imputation performance of the proposed method by comparison with some conventional methods (multiple linear regression, autoregressive integrated moving average model, and average historical method) by missing ratio. The applications in four scenarios demonstrate that the FCM-based imputation method outperforms conventional methods.

Operational characteristics of mixed traffic flow under bi-directional environment using cellular automaton

Mixed traffic flow composed of autos and non-autos widely exists in developing countries and areas. To investigate the operational characteristics of the mixed traffic flow consisting of vehicles in different types (large vehicles, cas, and bicycles), we develop a cellular automaton model to replicate the travel behaviors on a bi-directional road segment with respect to the physical and mechanic ftures of different vehicle types. By implementing the eesential parameters calibrated through the field data collection, a numerical study is carried out considering the variation in volume, density, and velocity with different compositions of mixed traffic flows. The primary findings include: the average velocity of traffic flow and total volume decrease 60% and 30% after incorporating 10% bicycles, respectively; the phenomenon of double-summit in terms of the total volume appears when the proportion of bicycle is beyond 60%; the maximal total volume starts to recover when the proportion of bicycle is higher than 10 %. Language: en

Capacity of Intersection with and without Connection Lane on the Left of Running Lane

The paper deals with problems of capacity assessment of intersection with or without the connection lane on the left of running lane. The paper describes capacity calculations for intersection without this lane according to Czech standards and proposes the possible procedure of calculation for intersection with the connection lane on the left of running lane. Comparison of capacity reserves is made on concrete example with real traffic flow volume values.

Comparison of Capacity of Intersection with Connection Lane on the Left of Running Lane and the other Types of Intersections

The paper deals with problems of capacity assessment of intersection with the connection lane on the left of running lane and intersections with traffic light and roundabouts. The paper describes capacity calculations for controlled intersections and roundabouts according to Czech standards and shows comparison of calculated capacity reserves of these types of intersections with reserves determined on intersection with the connection lane on the left of running lane on concrete example with real traffic flow volume values.

Capacity Analysis of Priority Intersections with Flare under Mixed Traffic Conditions

The gap-acceptance method is the common approach to assess the performance of the priority intersection which is implemented to regulate low volume of traffic flow. However, among the drawbacks of the gap-acceptance method are the non-compliance to the right of way, and the heterogeneous traffic condition. Conflict method has been developed to overcome these shortcomings. Surveillance equipment is used to obtain the required data, such as traffic volume and occupation time. The occupation time and approaching time of vehicle are used to calculate the capacity of vehicular movements for each conflict group. The results from intersections with flare and without flare are provided. Result comparison has also been made between the conflict method and the HCM 2000. The relationship between the occupation time and critical gap is discovered. The results of the conflict method are found to be comparable with the HCM 2000 using field data.

해상풍력발전단지의 대체통항로 통항안전성 평가에 관한 연구

In this paper, we analysed vessel traffic volume and patterns of traffic flow for ships using areas where included wind farm site and adjacent waters of Daejeong Offshore Wind Farm, and estimated traffic volume by classified navigational routes according to suggestion of rational routeing measures on the basis of classified patterns after installation of offshore wind facilities. Also, we assessed vessel traffic safety for each designed routeing measures on the basis of estimated traffic volume and proposed requisite countermeasures for the safe navigation of ships. With a result of analysing patterns of traffic flow, the current traffic flow was classified by 8 patterns and the annual traffic volume was predicted to 8,975 ships. On the basis of these, expected the vessel traffic volume according to designed four routeing mesaures after installation of wind farm. As result of assessing vessel traffic safety by using powered-vessel collision model of SSPA on the basis of the estimated traffic volume, the value of collision probability was less than safe criteria 10 -4 . Thereby we made sure usability of the designed routeing measures for the safe navigation of ships.

The Influence of Accumulation Area and the Length of Pedestrian Route on Functioning of Roundabouts with Traffic Signals

The paper presents issues related to the functioning of storage areas on roundabouts with traffic signals with high and very high traffic volumes. This kind of intersection is commonly used in the centres of Polish cities on multilane roads and fairly common in the case of tram lines running through a central island. The increase of traffic flow volumes on left turn and U-turn has made this type of roundabout difficult to operate. Small storage areas around central islands are critical places that significantly influence the capacity of this kind of intersection. The use of multiphase traffic signals causes major lengthening of crossing time for pedestrians which results in pedestrian delays at this kind of intersection. During the conducted analyses, microscopic models carried out in Transyt program, were used. They enabled the reconstruction of the traffic conditions and a few other important issues while assessing their capacity.

Modeling trailer-traffic flow on a Kenyan highway

Traffic flow modelling is studied in order to ease congestion on roads. However, congestion is also caused by irregular occurrences, such as traffic accidents, poor roads, vehicle disablement, spilled loads and hazardous materials. This study explored the area of poor roads which was considered to be as a result poor planning for road network repairs. Traffic flow was categorized to be either in low, intermediate, or high volume. Modelling for every flow required a different distribution namely the Exponential, Pearson type III and Normal distributions for low, intermediate and high traffic flow volume respectively. However, we modelled the trailers traffic flow using a model that covered all the 3 states, in this case,the Pearson type III distribution. Further,we investigated the shape of the probability distribution function assumed by the trailers. After data collection,extraction and analysis, Pearson type III distribution model was calibrated to fit. Lastly, Kolmogorov-Smirnov and Chi-square tests of goodness of fit was run on the observed data. Although, the data was also fitted into Normal, Erlang, Exponential, Beta and Gamma Distributions, Pearson type III distribution provided the best fit. Mathematics Subject Classification: 49K05 Keywords: Traffic flow, Modelling, Congestion, Road network, Trailers, Probability distribution Language: en

Low Multilinear Rank Approximation of Tensors and Application in Missing Traffic Data

The problem of missing data in multiway arrays (i.e., tensors) is common in many fields such as bibliographic data analysis, image processing, and computer vision. We consider the problems of approximating a tensor by another tensor with low multilinear rank in the presence of missing data and possibly reconstructing it (i.e., tensor completion). In this paper, we propose a weighted Tucker model which models only the known elements for capturing the latent structure of the data and reconstructing the missing elements. To treat the nonuniqueness of the proposed weighted Tucker model, a novel gradient descent algorithm based on a Grassmann manifold, which is termed Tucker weighted optimization (Tucker-Wopt), is proposed for guaranteeing the global convergence to a local minimum of the problem. Based on extensive experiments, Tucker-Wopt is shown to successfully reconstruct tensors with noise and up to 95% missing data. Furthermore, the experiments on traffic flow volume data demonstrate the usefulness of our algorithm on real-world application.

Level of Service Criteria of off-street Pedestrian Facilities in Indian Context using Affinity Propagation Clustering

To know how well roadways accommodate pedestrian travel or how they are pedestrian friendly it becomes necessary to assess the walking conditions. Estimation of PLOS criteria is very important as this is the first step of LOS analysis but this is not well defined in Indian context. The analysis followed in India is basically an adaptation of the Highway Capacity Manual (HCM) 2010 methodology. However, the defined ranges of various measuring parameters mentioned in HCM 2010 are more suitable for developed countries. In this research, an in- depth study has been carried out to define PLOS criteria of urban off-streets facilities in developing countries having heterogeneous traffic flow conditions. Defining LOS is basically a classification problem and to solve it Affinity Propagation (AP), a very recently developed cluster algorithm is used. Inventory details and speed data are collected from two important cities (Bhubaneswar and Rourkela) of Odisha state, India having less than a million populations, through the application of video camera.After the collection of data, based upon average pedestrian space, flow rate, speed and volume to capacity ratio (v/c), six categories of PLOS are estimated. PLOS ranges found from this study for six categories (A-F) using average pedestrian space are (in m2/pedestrian) >15.67, >(13.84-15.67), >(10.67-13.84), >(7.63-10.67), >(5.08-7.63), ≤5.08, flow rate are (in pedestrian/sec/m) ≤0.065, >(0.065-0.081), >(0.081-0.096), >(0.096-0.116), >(0.116-0.141), > 0.141, speed are (in m/pedestrian) >1.51, >(1.32-1.51), >(1.13-1.32), >(0.91-1.13), >(0.69-0.91), ≤0.69 and volume to capacity ratio (v/c) are ≤0.4, >(0.4-0.57), >(0.57-0.76), >(0.76-0.9), >(0.9-1), >1 for PLOS categories A, B, C, D, E and F respectively. The PLOS ranges defined in this study are proportionately lower than that mentioned in HCM (2010) because of highly heterogeneous traffic flow and low volume of pedestrian movements in less than a million population cities in Indian context.

Development of a Real-Time Model of the Occupancy of Short-Term Parking Zones

The lack of reliable information about the occupancy of on-street parking places in the inner districts of large cities causes an unnecessarily high amount of parking search traffic. Previous attempts to solve the problem rely on accurate information systems that navigate drivers to the next available parking space. They have failed due to high costs for roadside sensors and are also controversial, because they indirectly support car use. A service that informs road users early about the situation at the destination would support a shift towards public transport modes and reduce parking search traffic particularly at times of unexpectedly high parking pressure. The real-time occupancy model presented in this article does not aim to indicate the occupancy of single parking lots, but to provide a sufficiently accurate description and reliable prediction of the occupancy at the destination. Three existing real-time indicators were tested for their predictive power: (i) location data of mobile-phone parking; (ii) counts of car parks in the vicinity; and (iii) traffic flow volumes. Experimental results indicated that models using mobile-phone parking data have the potential to improve predictions of the occupancy rate by detecting exceptional deviations from the average day curve.

Formula omitted] state dependent travel time models and properties

One of the most important problems in today’s modeling of transportation networks is an accurate estimate of travel time on arterial links, highway, and freeways. There are a number of deterministic formulas that have been developed over the years to achieve a simple and direct way to estimate travel times for this complex task. Realistically, however, travel time is a random variable. These deterministic formula are briefly reviewed and also a new way to compute travel time over arterial links, highway, and freeways, is presented based on an analytical state dependent queueing model. One of the features of the queueing model is that it is analyzed within the context of the theoretical three-phase traffic flow model. We show that the model provides a quantitative foundation alternative to qualitative three-phase traffic flow theory. An important property shown with the model is that the travel time function is not convex, but a sigmoid S-shaped (i.e. logistic curve). Extensive analytical and simulation experiments are shown to verify the S-shaped nature of the travel time function and the use of the model’s method of estimation of travel time over vehicular traffic links as compared with traditional approaches. Finally, it is shown that the point-of-inflection of the S-shaped curve represents the threshold point where the traffic flow volume switches from Free Flow to Congested Flow.

Delay Analysis of Stop Sign Intersection and Yield Sign Intersection based on VISSIM

Travel efficiency and traffic safety of unsignalized intersections are two main objectives considered in traffic management and control. Stop sign and yield sign are the most common traffic signs to display the right of the way for all direction vehicle flows of unsignalized intersections. While in most cities in China, signalized control are always adopted for all intersections without considering level of traffic flow volume. This paper analyzes the difference between the stop sign intersection and yield sign intersection from the aspects of delay analysis. Firstly, intersections are designed in VISSIM software and traffic flow performance is validated via VISSIM. Then average vehicular delay under different traffic volumes is analysed under stop sign and yield sign respectively. Taking the lowest delay as the optimal objective, the critical traffic volume is proposed to set stop sign or yield sign. The results can be used in practice to guide the installation of traffic signs.

Model of a Traffic Circle

In this paper, the relationship between the number of entrance and exit, and traffic flow volume. When the number of entrance and exit is equal to 4 or greater than 4, and when the weaving section length is taken into consideration, the relationship has been studied in detail. For a given traffic circle, the road conditions in, around and out of the circle have been determined. We treat these calculation results as the reference criteria and construct two models. The one is regular critical space model and the other is two-left-turn phase control model. Finally, taken by the example of Lianban Circle in Xiamen, China, the above models have been tested and their strengths and weaknesses have been analyzed.

Performance of the Priority Control Strategies for Bus Rapid Transit: Comparative Study from Scenario Microsimulation Using VISSIM

Bus rapid transit (BRT) has a great potential to improve the service level of transit system and has been implemented in many Chinese cities. However, the priority it can provide to buses has not been explored fully. Therefore, this study mainly investigated two advanced control strategies (signal priority using advanced detection and transit speed control). Signal priority using advanced detection is a strategy which detects one cycle ahead of buses’ arrival in order to adapt a more flexible control algorithm to provide signal priority for buses. Another is transit speed control, which provides priority at intersections for buses by controlling the speed of them and predicting their arrival at certain intersection. These two advanced strategies were modeled and evaluated using simulation software VISSIM and presented better performance than other three scenarios (base case, exclusive bus lane, and conventional transit signal priority). Only the eastbound direction would be researched as its traffic flow and bus volume are much larger than those of the other direction. Data used in this model was collected in Yingtan City. It is also shown that both the operation of BRT and the efficiency of private traffic can be much improved by applying the two strategies proposed above.