Gaurang Joshi

Time occupancy as measure of PCU at four legged roundabouts

This study is carried out to estimate the passenger car unit (PCU) values of different vehicle categories at a typical four-legged roundabout based on the concept of time occupancy. A stream equivalency factor (k) has also been developed based on the estimated PCU to convert the heterogeneous traffic flow into a homogenous stream equivalent without making use of PCU factors. Relationship between entry flow and circulatory flow has been plotted based on the observed data corresponding to the time period in which there was queue formation in the approach. Further, estimated critical gap and follow-up time have been used to derive the capacity by HCM 2010 equation. A multiplicative adjustment factor is suggested for the use of HCM 2010 equation directly in the field to estimate entry flow under heterogeneous traffic condition. The study results may be suitable for revising the code of practice, named IRC 65–1976, and useful for ongoing national-level efforts of developing Indian Highway Capacity Manual.

Effect of traffic composition and emergency lane on capacity: a case study of intercity expressway in India

ABSTRACT The study is intended to investigate the effect of traffic composition and the use of a paved emergency lane on capacity. Ahmedabad–Vadodara four-lane divided intercity expressway (Mahatma Gandhi expressway, designated as NE-1) which has an emergency lane on either side is taken as a case study. For modeling traffic flow on expressway, a microscopic simulation technique is employed in this study. The simulation model was developed, calibrated, and validated for rendering as well as replicating the real traffic conditions. Results of the study show that the capacity is greatly influenced by emergency lanes and traffic composition. The result of the present study is expected to highlight the ongoing national-level efforts of developing guidelines for Indo-Highway Capacity Manual.

Multimodal of Lateral Transport System: A Case Study of Successful Cities Worldwide

These days, inefficient utilization of transportation network has turned out to be one of the significant issues for fast growing urban regions. Numerous initiatives are taken by the governments keeping in mind the end goal to evolve sustainable transportation by increasing the mode share of public transportation system; particularly the bus services. The major deficiency with the present public transport system is lack of proper first and last mile connectivity, delays of buses due to traffic density, improper route management of buses, etc. Past studies have demonstrated that coordinated planning and usage of multimodal transport system may prompt increment in mode share of public transport and may enhance effectiveness of transportation network. In this context, the present paper is an endeavor to examine the current multimodal transportation framework running effectively in the global cities, London, Hong Kong, and Singapore, with exemplary multimodal transport systems The five noteworthy mainstays of the multimodal transport that is physical joining, operational incorporation, informational integration, toll coordination, and institutional combination are reviewed briefly for each the selected urban areas. Focus of the present paper is simply to see how the idea of multimodal transportation framework can help the local authority to run the transportation system in a productive way.

Methodological Framework for Modeling Following Behavior of Vehicles Under Indian Traffic Scenario

The present research work is originated with an intent of studying traffic flow characteristics on intercity. For this purpose, two expressway sections: (i) Pune-Mumbai Expressway and (ii) Ahmedabad-Vadodara Expressway were selected, as these are the best available roads in category of intercity expressways, in India. During the course of work, it was found that data may not be fully adequate to develop Measure of Effectiveness (MOEs) thresholds. Consequently, simulation-based approach is to model the traffic flow on selected study sections. With this motivation, simulation model, namely, VISSIM-9.0 was calibrated using newly developed methodology for mixed traffic conditions. In particular, driving behavior parameters were calibrated using high-quality vehicular trajectories. A well-calibrated simulation model was then applied for developing speed-flow-density fundamental diagrams, and thereby determining capacity and Level-of-Service (LoS) thresholds using density and V/C ratio. It was found that the capacity value for six-lane divided expressway (three lanes in each direction) is determined as about 7500 PCU/h/direction, which reasonably matches with the US-HCM (2010) guidelines. It is anticipated that the proposed method of calibrating vehicle-following driving behavior using high-quality trajectory data is transferable to other mixed traffic conditions.

Application of Trajectory Data for Investigating Vehicle Behavior in Mixed Traffic Environment

The research work reported here investigates driving behavior under mixed traffic conditions on high-speed, multilane highways. With the involvement of multiple vehicle classes, high-resolution trajectory data is necessary for exploring vehicle-following, lateral movement, and seeping behavior under varying traffic flow states. An access-controlled, mid-block road section was selected for video data collection under varying traffic flow conditions. Using a semi-automated image processing tool, vehicular trajectory data was developed for three different traffic states. Micro-level behavior such as lateral placement of vehicles as a function of speed, instant responses, vehicle-following behavior, and hysteresis phenomenon were evaluated under different traffic flow states. It was found that lane-wise behavior degraded with increase in traffic volume and vehicles showed a propensity to move towards the median at low flow and towards the curb-side at moderate and heavy flows. Further, vehicle-following behavior was also investigated and it was found that with increase in flow level, vehicles are more inclined to mimic the leader vehicle’s behavior. In addition to following time, perceiving time of subject vehicle for different leading vehicles was also evaluated for different vehicle classes. From the analysis, it was inferred that smaller vehicles are switching their leader vehicles more often to escape from delay, resulting in less following and perceiving time and aggressive gap acceptance. The present research work reveals the need for high-quality, micro-level data for calibrating driving behavior models under mixed traffic conditions.

Impact assessment of driver speed limit compliance behavior on macroscopic traffic characteristics under heterogeneous traffic environment

ABSTRACT This study aims to evaluate the change in roadway capacity with increasing driver compliance levels for a given posted speed limit. The simulation experiment was conducted for all-cars traffic and varying traffic compositions on an eight-lane divided multi-lane urban road in Delhi, India. It is found that with increasing driver compliance level for a given posted speed limit, there is an increase in roadway capacity but with marginal increase in the critical speed of the traffic stream. Also, higher critical speeds are observed at very high and very low compliance levels. Furthermore, based on speed–flow plot developed from field observed conditions, the present compliance on selected multilane urban road at stream level is found as 40% approximately. The results of the study may be useful in underlining the importance of driver compliance with posted speed limit along with its enforcement for better safety.

New Approach for Estimating Passenger Car Units on Multilane Urban Roads with Heterogeneous Traffic Conditions

AbstractThis paper illustrates a newly developed methodology for passenger car unit (PCU) estimation under non-lane–based heterogeneous traffic conditions on multilane urban roads, using area occup...

Novel Area Occupancy–Based Method for Passenger Car Unit Estimation on Multilane Urban Roads Under Heterogeneous Traffic Scenario

This research was aimed at developing an area occupancy–based method for estimating passenger car unit (PCU) values for vehicle categories under heterogeneous traffic conditions on multilane urban roads for a wide range of traffic flow levels. First, PCU values of vehicle categories were determined according to the Transport and Road Research Laboratory definition and replaced the commonly considered measure of performance speed with area occupancy using simulation. The PCU values obtained were found to be significantly different for different volume-to-capacity ratios; this result shows that the PCU value is dynamic in nature. While the dynamic nature of PCU values is well appreciated, practitioners may prefer a single set of optimized PCU values (unique for each vehicle category). Hence, a new method with a matrix solution was proposed to estimate the optimized or unique set of PCU values with area occupancy as the performance measure. To check the credibility of the proposed method, the estimated PCU values were compared from existing guidelines regulated by the Indian Roads Congress (IRC) and values estimated with the widely accepted dynamic PCU concept of speed–area ratio. Results show that the PCU values suggested by IRC and the dynamic PCU concept using the speed–area ratio underestimate and overestimate the flows, respectively, at different traffic volumes. However, the values obtained with the area-occupancy concept were found to be consistent with the traffic flow in a cars-only traffic situation at different flow conditions. The derived set of optimized PCU values proposed can be useful for traffic engineers, researchers, and practitioners for capacity and level-of-service analysis under heterogeneous traffic conditions.

Modeling expressway lane utilization and lane choice behaviour: a case study on Delhi–Gurgaon Expressway

Abstract Expressways in India are vastly different from those in the developed countries due to its varied vehicle composition and quasi-lane disciplined traffic movement. Relatively, limited research has been done on the lane utilization and lane choice behavior of different vehicle types on Indian expressways. This study thus focuses on building a structural equation model to study the influence of different vehicle categories and stream speed on lane utilization of Delhi-Gurgaon Expressway and further develop three lane choice models using lane utilization factor, class of vehicles, and stream speed as independent variables. The three lane choice models are validated with observed lane wise traffic composition and lane discipline. From the sensitivity analysis of parameters affecting lane choice, it is observed that stream speed and class of vehicle significantly affect the drivers’ lane choice behavior. The results of this study in the form of lane utilization and lane discipline behavior by different vehicle types are used to differentiate the expressway traffic characteristics from other road types in India. The findings are also helpful in developing and calibrating the microscopic simulation models for Indian expressways.

Determination of Pedestrian Level of Service for Undivided Stairways at Suburban Rail Stations in Developing Countries

Bidirectional pedestrian movement is predominant on undivided stairways. Under a given situation, it is imperative to assess the level of service (LOS) provided to pedestrians on a stairway. Currently, limited guidelines are available for assessing the LOS on undivided stairways in South Asian countries. With this motivation, the current study was conducted to develop LOS criteria for undivided stairways by using the case of a busy suburban railway station at Dadar in Mumbai, India. The LOS can be considered as the classification of different pedestrian flow states on the basis of facility performance. This study is focused on employing the k-means clustering technique to define the LOS thresholds of relevant flow variables. Data on four major variables of pedestrian flow are used: space per pedestrian, flow rate, walking speed, and volume-to-capacity ratio. Derived LOS thresholds are then delineated by using the rate of change in slope for the average walking speed of pedestrians. LOS thresholds are further validated for different percentile values of pedestrian flow data to check whether given data sets fall within the range of established LOS thresholds. Ranges of the flow parameters defined for LOS criteria found in this study are significantly different from those reported in the literature and in manuals in developed countries such as the U.S. Highway Capacity Manual. This difference may be attributed to the demographic and sociocultural characteristics of the pedestrians. The results and approach adopted here can be useful for practitioners to assess the LOS of stairways operating under similar pedestrian flow conditions and to respond appropriately for their improvement. The study results can also be useful for the ongoing project of developing a highway capacity manual for India.