Indrajit Ghosh

Kriging-Based Approach for Estimation of Vehicular Speed and Passenger Car Units on an Urban Arterial

AbstractUse of speed-prediction models sometimes appears as a feasible alternative to laborious field measurements, particularly when field data cannot fulfill designers’ requirements. However, dev...

The Effect of Countdown Timer on the Approach Speed at Signalised Intersections

Countdown timers are being installed at major intersections of India cities without analyzing their influence on intersection safety and efficiency. This study tries to investigate the effect of green signal countdown timer (GSCT) component on the vehicular approach speeds. Two approaches of two different signalized intersections, one with countdown display and another without it, have been studied for the present study. Presence of GSCT is found to be linked with fewer red light violations (RLVs) cycles, lower number of mean RLV per RLV cycle, higher vehicular speeds during the phase transition at different locations upstream to the stop line, more number of speeding cars, and higher stop line crossing speed during amber. Overall, GSCT encourages drivers to travel with higher speed which could lead to accidents. This observation makes researchers skeptical about its real effectiveness. An additional safety based study can provide better insight about the utility of GSCT.

Effects of Dynamically Activated Emergency Vehicle Warning Sign on Driver Behavior at Urban Intersections

Emergency vehicles are subjected to substantial risks when traveling through urban signalized intersections, particularly when the cross street traffic is provided with a green signal indication. Much of this risk is due to a lack of awareness of the approaching emergency vehicles on the part of the cross street traffic. To mitigate this problem, a dynamically activated emergency vehicle alert system was developed to provide an additional visual cue to motorists of an impending emergency vehicles approach. The alert system consists of an LED case sign, mounted near the curb line adjacent to a traffic signal, which displays an emergency vehicle symbol when activated by a transmitter installed in the emergency vehicle as it approaches an intersection. A before-and-after evaluation of these warning signs was conducted at five test intersections in two suburban communities near Detroit, Michigan. The results showed that the alert system significantly improved driver awareness and behavior at all study locations as determined by comparing various measures of effectiveness. Overall, the proportion of drivers who yielded the right-of-way to an approaching emergency vehicle increased from 77.1% before installation of the warning signs to 96.6% after installation. Drivers also tended to yield sooner when the alert system was in use, and when violations of the emergency vehicle right-of-way did occur, they generally happened sooner.

Determination of Passenger-Car Units on Two-Lane Intercity Highways under Heterogeneous Traffic Conditions

AbstractThe introduction of the passenger car unit (PCU) concept by the 1965 edition of the Highway Capacity Manual (HCM) enabled researchers around the world to deal with mixed traffic flow. Though some researchers have tried to show the dynamic nature of PCU factors, most of the studies in the world, as well as the latest standards being followed, still provide static PCU values for various types of vehicle categories. The present study demonstrates the dynamic nature of PCU factors on two-lane intercity highways under highly heterogeneous traffic composition. They are estimated based on speed and size of vehicle type in the traffic stream with respect to a standard passenger car. Simultaneous equations are formulated to calculate the speeds of different types of vehicles for a given traffic composition and traffic volume on the road, which lead to the determination of PCU factors. While many plots are made to describe the effect of traffic composition and volume on PCU of a vehicle type, it is felt tha...

Passenger Car Unit of Vehicles on Undivided Intercity Roads in India

The majority of the roads in India are of single-lane or two-lane width. Due to budget constrains sometimes these roads are constructed with one and a half lane width (5.5 m) and is called intermediate-lane road with traffic moving on both directions. To simplify the analysis of mixed traffic on such roads, different types of vehicles are converted into equivalent number of passenger cars by using Passenger Car Unit (PCU). In the present study, an attempt is made to study the effect of the carriageway width on PCU of different vehicle categories. Data are collected at ten sections of intercity roads in different states in India. The results show that PCU value for a vehicle type varies with traffic volume and composition on the road and the carriageway width of the road being used. For example the average PCU for a big car varies from 1.46 to 1.59 on two-lane roads, 1.23 to 1.55 on intermediate roads and 1.58 on single-lane roads. All these results are discussed in this paper.

Saturation Flow Model for Signalized Intersection under Mixed Traffic Condition

Saturation flow is one of the most important functional parameters at signalized intersections. It is to be noted that saturation flow is a functional measure of the intersection operation, which indicates the probable capacity if working in an ideal situation. However, determination of the saturation flow is a challenging task in developing countries like India where vehicles with diverse static and dynamic characteristics use the same carriageway. At the same time, it is influenced by several other factors. In this context, the present research is carried out to examine the effects of traffic composition, approach width and right-turning movements on saturation flow under heterogeneous traffic conditions. This paper proposes a model for computing saturation flow at the signalized intersection under mixed traffic condition based on Kriging approach. A detailed comparison of the mean saturation flow values obtained by the conventional method, regression method, and Kriging method has also been presented. Low mean absolute percentage error values (<5%) have been obtained for saturation flow by Kriging method with respect to the conventional method. Finally, the proposed models are used to evaluate the impact of right-turning vehicles on saturation flow under shared lane condition.

Hydroelectric Flow Optimization of a Dam: A Kriging-Based Approach

This paper presents a novel approach for hydroelectric flow optimization. The proposed approach integrates Kriging into the framework of genetic algorithm (GA). This coupling reduces the computational effort associated with conventional GA without affecting the accuracy. The proposed approach has been used for hydroelectric flow optimization. For the model considered, revenue generated is dependent on (a) hourly turbine flow, (b) hourly spill flow, (c) hourly electricity price and (d) storage level of reservoir. Two case studies have been performed by varying the simulation time considered. For the first case, the simulation is run for 50 h. It is observed that the proposed approach yields accurate result at significantly reduced computational cost. On contrary for the second case, the simulation is run for 20 days. Due to huge computational cost involved, it was not possible to generate benchmark solution. Hence, only the results obtained using the proposed approach have been reported. The results obtained are indicative of the fact that the proposed approach can be utilized for optimization of large-scale system from an affordable computational cost.

What Characterizes a Vehicle as Follower on Two-Lane Intercity Highways under Heterogeneous Traffic Conditions

AbstractThe presence of a high proportion of vehicles in the following condition indicates that a particular roadway facility is performing poorly. Due to lack of related standard guidelines, plann...

Delay at Signalized Intersections under Mixed Traffic Conditions

AbstractDelay caused to an individual vehicle at a signalized intersection is a performance measure to assess the level of service. While dealing with delay in Indian traffic conditions, researcher...