Akhilesh Kumar Maurya

Microscopic Analysis of Cellular Automata Based Traffic Flow Models and an Improved Model

Abstract A large number of cellular automata (CA) based traffic flow models have been proposed in the recent past. Often, the speed‐flow‐density relations obtained from these models are only presented and their apparent similarities with observed relations are cited as reasons for considering them as valid models of traffic flow. Hardly any attempt has been made to comprehensively study the microscopic properties (like time‐headway distribution, acceleration noise, stability in car‐following situations, etc.) of the simulated streams. This article proposes a framework for such evaluations. The article also presents the results from the evaluation of six existing CA‐based models. The results show that none of them satisfy all the properties. A new model proposed by the authors to overcome these shortcomings is briefly presented, and results supporting the improved performance of the proposed model are also provided.

Multivariate analysis of microscopic traffic variables using copulas in staggered car-following conditions

ABSTRACT The current study investigates the applicability of the copula approach to capture the potential dependence among microscopic traffic variables (time headway, speed and centreline separation) and the joint probabilistic behaviour of the variables in staggered car-following conditions, using trajectory data from video recording of a four-lane divided road in Kolkata, India. As importantly, the study indicates that although Frank, Clayton and Gaussian copulas provide better fits for the two-dimensional traffic variables; considering both the positive and negative associations among the three microscopic variables, and checked by the goodness-of-fit measures based on Rosenblatt’s transformation, the Gaussian copula is found acceptable to model the multivariate joint distribution and is hence, employed to construct the joint and conditional probabilities among the three variables. Overall, the findings of the study justify the need to explicitly consider centreline separation and vehicle speed in time headway modelling for elucidating the integrated driving behaviour of non-lane-based traffic streams, a proper consideration of which will further ameliorate the realistic replication of rider’s behaviour in simulation modelling.

Determinants of time headway in staggered car-following conditions

Abstract Precise understanding of the factors affecting the choice of following time headway in staggered car-following conditions is essential on the part of traffic modelers to provide a detailed representation of traffic flow, which has a predominant role in microsimulation model development, safety evaluation, capacity estimation and evaluation of traffic management strategies. Using trajectory data from video recordings, an evaluation of the impact of a number of factors (i.e. road width, centerline separation, lead vehicle type) on the following headway of a driver is undertaken in this study. A seemingly unrelated regression (SUR) model for time headways is also developed to examine the correlation of headways with different determinants and speeds of following vehicles. Results of the study suggest that though there is a direct relationship between speed and headway, the extent of off-centeredness between the interacting pair and vehicle type-specific interactions need to be considered to develop mixed-traffic microsimulation models.

Bivariate modeling of time headways in mixed traffic streams: a copula approach

ABSTRACT Vehicle headway distributions provide an efficient representation of the uncertainties in traffic flows that have diverse applications in capacity estimation, safety evaluation, planning, design of roadway systems and in traffic operation studies. The current study is aimed at investigating the applicability of the copula approach to accommodate the dependence structure between vehicle headway and the centerline separation between the interacting vehicles in vehicle-following conditions for different vehicle-pair combinations, using trajectory data from video recordings. The results of the study indicated that Frank copula could model the joint distribution for almost all leader–follower vehicle pairs. As importantly, the joint distribution and the conditional non-exceedance probabilities of time headways demonstrated the importance of explicitly considering centerline separation in time headway modeling and the need to develop bivariate vehicle type-specific behavioral models for mixed traffic streams, in order to augment the reliability of existing models, better understanding and modeling of non-lane-based traffic streams.

Modelling of motorised two-wheelers: a review of the literature

ABSTRACT Motorised two-wheeler (MTW) has emerged as the most widely used transportation mode for short distance trips in many Asian and European countries because of its affordable price and flexibility in manoeuvring through traffic. Its small size and aggressive riding patterns can considerably affect the overall traffic flow characteristics and safety. Modelling the characteristic behaviour and complex movement patterns of motorised two-wheelers is essential due to their pronounced role in microscopic traffic simulations, traffic management strategies, safety evaluation, transport planning and intelligent transportation systems. This paper begins with an overview of the determinant factors used for MTW modelling, followed by a critical review of various modelling approaches that have been adopted to depict the movement patterns of MTWs. The review concentrates on (i) identifying the factors mostly studied with respect to MTW-research, (ii) discussing the potential and limitations of each modelling approach and (iii) reporting some of the aspects that need further consideration for modelling MTWs in heterogeneous mixed traffic streams. The findings of the paper suggest that an integrated approach can be more viable to depict the unique riding patterns of motorised two-wheelers and some possible directions for future studies are also proposed.

A review of pedestrian flow characteristics and level of service over different pedestrian facilities

Present paper reviewed the past studies on pedestrian flow characteristics (such as speed, flow, density, space, free-flow speed and jam density) and development of Pedestrian Level of Service (PLOS) for various pedestrian facilities (i.e., sidewalk, walkway, crosswalk, grade separated, stairways and escalators). Fundamental relationships (between speed and density) were observed over different facilities and were found to be significantly different. The fundamental relationships for sidewalk facility predicted the range of free flow speeds to be 65 − 85 m / min and jam densities to be 3 . 5 − 5 . 3 ped / m 2 . The minimum and maximum pedestrian speeds over sidewalk facility in different countries observed were 52 m / min and 98 m / min respectively, with a mean speed of 79 m / min . The male pedestrians walked at 4 − 9 m / min higher speed in comparison to their female counterparts; while the older pedestrians walked at 15 − 20 m / min lower speed than the younger ones over the various types of crosswalk facilities. Similarly, speed-density relationships for ascending and descending stairways showed that the difference between the two directions varied between 4 − 12 m / min , and that the speed was significantly higher in case of descending direction. Moreover, the jam densities for stairways were also observed to be lower in case of descending direction, as the pedestrians generally maintain higher gap (than in ascending direction) with other pedestrians in front to avoid pushing and the risk of falling down. The flow characteristics were significantly influenced by the type of facility, width, age, gender and location of the study. Primarily factors such as physique (height), culture (dress), attractions (presence of hawkers located along sidewalks), friction (due to parked vehicles), purpose of walking trip and environmentl conditions were the main reasons for pedestrians of countries such as Saudi Arabia, Iraq, Bangladesh, Indonesia and Sri-Lanka to walk significantly slower than the counterparts pedestrians in the USA, UK or Canada. The review conducted on the PLOS mainly looked into the type of survey conducted (qualitative vs. quantitative), LOS parameters and the various software/models used in development of LOS. Researchers from the USA and Japan preferably used both qualitative and quantitative approaches in defining LOS over sidewalks; while in India, China and Malaysia qualitative method was highly preferred. Pedestrian volume, safety, surface, obstruction and width were observed as essential parameters for qualitative survey while density, flow rate, pedestrian speed and width were used in quantitative survey for sidewalks. In developing the PLOS over sidewalk facility; Conjoint analysis, Landis method, HCM method, affinity propagation cluster algorithm and Gainesville method were preferred by various researchers. Studies conducted over crosswalk facility measured space, flow rate, vehicle volume and delay as the most significant factors in developing LOS based on quantitative technique; while vehicle speed, pedestrian volume and traffic control were mostly used for LOS development using qualitative technique.

Economic Evaluation of Transportation Project: A Case Study of Ferry System for IIT Guwahati

Transportation projects hold a major share of the economic investments made in India. Evaluation of alternate strategies is necessary to optimize gain from investments in terms of facilities and costs. Various methods like NPV, IRR can be used for feasibility studies of projects. The study consists of measuring the direct--indirect costs and overall benefits. For the economic evaluation of the proposed project, we have used a cost-effective approach comparing the costs and the outcomes from the different means of transportation. In IIT Guwahati campus, the major means of public transportation is a Bus service provided by Green Valley Travels Private Ltd. The rise in campus population is pushing this service to an extreme level causing discomfort to passengers. Located on the north side of river Brahmaputra, IITG Campus is 20 km away from the main Guwahati city with Saraighat Bridge being the only connecting link by road. Saraighat Bridge is the first rail-cum-road bridge constructed over the River Brahmaputra in Guwahati in 1962 by the then Prime Minister Jawaharlal Nehru. It is the only bridge over the river Brahmaputra for about 100 km upstream and downstream. Daily huge amount of highway traffic is forced to take Saraighat Bridge in order to enter city and northeast States, resulting in slow moving long queues, almost choking the vehicular flow. This traffic jam on the way to city is responsible for the further increment in travel time. It takes about 75–90 min to reach city due to high level of congestion. The alternate ways to reach city are either by Auto-rickshaw or by Ferry. The existing Govt. Ferry Transport hardly takes 20 min to reach city, but there is no proper facility available to reach Ferry-Ghat. Our work elaborates the socioeconomic evaluation of establishing Ferry Transportation system from the IITG campus to Guwahati city. After a thorough survey of the costs and benefits involved, final Cost benefit analysis of the proposed ferry system show a high internal rate of return. The project appears to be beneficial both in terms of cost-saving and time-saving. Practical implementation of the proposed project will promote overall socioeconomic growth.

Modelling the Gap Acceptance Behavior of Drivers of Two-Wheelers at Unsignalized Intersection in Case of Heterogeneous Traffic Using ANFIS

The gap acceptance concept is an important theory in the estimation of capacity and delay of the specific moment at unsignalized junctions. Most of analyzes have been carried in advanced countries where traffic form is uniform, and laws of priorities, as well as lane disciplines, are willingly followed. However, in India, priority laws are less honored which consequently create more conflicts at intersections. Modeling of such behavior is complex as it influenced by various traffic features and vehicles’ as well as drivers’ characteristics. A fuzzy model has been broadly accepted theory to investigate similar circumstances. This article defines the utilization of ANFIS to model the crossing performance of through movement vehicles at the four-legged uncontrolled median separated intersection, placed in a semi-urban region of Ahmedabad in the province of Gujarat. Video footage method was implemented, and five video cameras had been employed concurrently to collect the various movements and motorists’, as well as vehicles’ characteristics. An ANFIS model has been developed to estimate the possibilities of acceptance and rejections by drivers of two-wheelers for a particular gap or lag size. Seven input and one output parameters, i.e. the decision of the drivers are considered. Eleven different diverse combination of variables is employed to construct eleven different models and to observe the impact of various attributes on the correct prediction of specific model. 70 % observations are found to prepare the models and residual 30 % is considered for validating the models. The forecasting capability of the model has been matched with those experiential data set and has displayed good ability of replicating the experiential behavior. The forecast by ANFIS model ranges roughly between 77 and 90 %. The models introduced in this study can be implemented in the dynamic evaluation of crossing behavior of drivers.

Vehicle Classification Using Adaptive Neuro-Fuzzy Inference System (ANFIS)

Accurate vehicle classification and traffic composition data are an important traffic performance measures which are used in many transportation applications. In this paper, an attempt is made to develop a model to classify the vehicles into five categories: light commercial vehicle, car/jeep/van, two-axle truck/bus, three-axle truck, and multi-axle vehicles based on the fuzzy inference system (FIS) and adaptive neuro-fuzzy inference system (ANFIS) algorithms. Wheelbase and average track of the vehicles are the two parameters considered in the classification of the vehicles which can be measured easily in the field. Two wheelers and three wheelers are not considered in this study as these can be easily classified based on the selected parameters. Both of these parameters of all classified vehicles on Indian roads have been collected from various sources including the Web sites of automobile companies. Vehicle classification has been done for decided classes of vehicles to check the accuracy and performance of the model. Model with modified FIS by ANFIS is more significant than a model with the initial FIS. The overall classification rate is significant with 89.34 % accuracy.