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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. [ABSTRACT FROM AUTHOR]

The present study focuses on modeling roundabout in heterogeneous condition and understanding the effect of change in two-wheeler composition on the entry capacity using microscopic simulation technique. A four-legged roundabout of 25m diameter, located in the city of Chandigarh, India was considered as the study area. As Indian traffic flow is highly heterogeneous due to the presence of vehicles with varying physical and operational characteristics, each vehicle modelled separately in PTV VISSIM. Model calibrations were performed using speed distributions, conflict areas, priority rules, and driving behavior parameters. Comparison with the field data obtained from the study roundabout (indicates the applicability of the developed simulation model in assessing the hypothetical scenarios. Study results indicate that the PCU values remain steady under varying compositions of two-wheelers in the traffic stream. In addition, the effect of two-wheeler proportion on roundabout capacity is insignificant in the study area. [ABSTRACT FROM AUTHOR]

Models developed in Highway Capacity Manual (HCM) are not suitable to cater to the effects of mixed traffic conditions and hence, its use is unjustifiable. This research investigates such a challenging problem as the effect of undesignated pedestrian crossings on the entry capacity of roundabouts. For the present study, field survey data were collected using video cameras from three roundabouts such that the base section (roundabout without pedestrian influence) and non-base sections (with pedestrian influence), both scenarios, were captured. A modified HCM equation was developed to estimate entry capacity and further, the reduction in capacity with respect to pedestrian volume is determined. Lastly, a relationship was developed to check the effect of pedestrian crossflow on the entry capacity. The relation shows that capacity reduced to 1841 Passenger Car Unit (PCU/h) when the pedestrian flow increased to 288 pedestrians/hour. [ABSTRACT FROM AUTHOR]

Thermal power plants in India produce a large quantity of fly ash, which is harmful to the environment. Underutilization of fly ash and the scarcity of natural minerals have created the need for an unusual construction strategy to prevent huge waste dumps on valuable land and to preserve fast-depleting resources. A study was conducted to determine the efficacy of lime-stabilized fly ash blended with quarry fines as flexible pavement subbase materials. The laboratory investigations were conducted to determine compaction characteristics, unconfined compressive strength, California bearing ratio (CBR), and durability to obtain the optimal quarry fines, fly ash, and lime (QFL) mix. The durability of QFL mixes was studied using 12 wetting–drying cycles. Using the strength and durability criteria specified by the Indian Road Congress, the optimum mix proportion of 40Q:60F+3L was determined. Pavement analyses were performed using the IITPAVE program. The QFL mix was observed to be superior to conventional granular subbase (GSB) layer material in terms of service life and cost-effectiveness. A field investigation was carried out on trial test sections constructed using the optimum QFL mix and GSB in the subbase layer of pavement. Field dry density and dynamic cone penetrometer (DCP) tests were performed on the compacted subgrade and subbase layers to assess the desired quality assurance in the construction of test sections. The early structural performance assessment of pavement sections using a falling weight deflectometer (FWD) test indicated that QFL could effectively replace conventional GSB. [ABSTRACT FROM AUTHOR]

Present study evaluates the various congestion indexes in terms of speed performance index, volume to capacity ratio and congestion index based on travel time on the urban roadway network of 5.7km in length, operating with mixed traffic conditions (traffic with varying static and dynamic characteristics of vehicles). The mitigations measures have been proposed to cater to the present traffic demand by converting the uncontrolled intersection to a partially controlled or signal-controlled intersection. In order to check the effectiveness of such mitigation measures, various scenarios have been generated in the developed and a well calibrated simulation model. It has also been observed that the speed performance index has improved by 8.88 percent while providing channelized intersection at one of the point elements and 11.52 %when the two-point elements have converted to channelizing intersection. [ABSTRACT FROM AUTHOR]

The efficiency of manual toll transactions is highly dependent upon the service performance of tollbooth operators. The latter is a multi-attribute decision making (MADM) problem, as the performance of the tollbooth operators is influenced by various criteria such as traffic operation, tollbooth ergonomics, etc. The present study has used the analytical hierarchy process (AHP), a MADM method, to evaluate the criteria affecting the service performance of tollbooth operators. The identified criteria are further ranked based on their significance so that the concessionaire as a decision-maker may identify the most important criteria and take appropriate decisions to improve the service performance of tollbooth operators. Based on the available literature, the criteria affecting the service performance of tollbooth operators included service time, their capability in terms of service training, shift timings and personal safety. A structured AHP questionnaire was prepared for developing the relative importance matrix from the perception of the tollbooth operator. The weights were obtained from the AHP relative importance matrix and used for setting the priorities. The results show that the operator's capability as a criterion and training given to tollbooth operators as a sub-criterion have the highest priorities with weights of 0.51 and 0.214 respectively (global weight). Finally, sensitivity analysis was performed to check the effect of change in weights of criteria on the service performance of tollbooth operators. Thus, the output could be used by the concessionaire to meet the requirements of the tollbooth operators for enhancing their service performance in order to improve the service level of toll plazas. [ABSTRACT FROM AUTHOR]

Roundabouts have proven to be an effective intersection design method for smooth traffic flow movements and improved safety. Previous studies show that VISSIM, commercial traffic simulation software, can be used as a proficient tool for modeling and efficiently analyzing roundabouts. This paper focuses on developing a methodology for modeling roundabouts in India using VISSIM. Three typical roundabouts were chosen from the northern part of India. Calibration and validation of the model were performed to ensure the correctness of the model. The average delay and volume to capacity ratio (v/c ratio) were compared for developing the level of service (LOS) thresholds for Indian conditions. The thresholds are compared with existing guidelines provided by the HCM 2010 and AUSTROADS. In addition, the methodology for determining modification factors for applying HCM 2010 delay model in Indian traffic conditions is defined. [ABSTRACT FROM AUTHOR]

The increased scarcity of natural quarry material has resulted in increases in the cost and burden on the environment. Pavement materials comprising asphalt coated aggregates that can be reused are called reclaimed asphalt pavement (RAP). RAP is crushed and screened, and then blended with one or more stabilization agents to produce a stabilized base or subbase aggregate. In the present study, the influences of fly ash dosage, lime dosage, and curing period on the strength, stiffness, and durability characteristics of RAP fly ash–lime (RFL) mixes were studied for utilization as a base layer material in flexible pavements. The dry density and moisture content relationship were determined by conducting a modified proctor test on all RFL mixes. Unconfined compression tests were conducted on specimens with different dry weight percentages of fly ash (10%–25%) and lime (5%–10%) content for different curing periods (0, 7, and 28 days). The optimum mix obtained as RFL2 had the proportions 70% RAP:22.5% fly ash:7.5% lime. A resilient modulus of 540 MPa at 28 days was observed for RFL2. The durability of RFL2 tested using the resistance index and a wet–dry cycle (weight loss) was observed to be 0.88% and 7.3%, respectively. Pavement analyses were performed for a pavement system with three layers using the KENLAYER program. The RFL2 mix as the base layer material was found to be superior to conventional wet mix macadam, hence the service life of an RFL2 pavement would be higher. Trial sections of the stabilized base and conventional pavement were constructed on a major district road. The falling weight deflectometer showed a better modulus (286 MPa) in RFL2. An RFL mix could therefore be used in a stabilized base layer to replace a conventional base layer. [ABSTRACT FROM AUTHOR]

The present study explores the spatial and temporal variation of rear-end conflicts at signalized intersections under mixed traffic conditions with poor lane discipline (disordered traffic conditions). Vehicular trajectory data was extracted using the videographic field data of three signalized intersections in India. Due to disordered traffic conditions, a simple and robust method is proposed to identify the leader and follower vehicle pairs for identifying rear-end conflicts. Spatiotemporal variation of identified conflicts is investigated using two popular surrogate safety measures (SSMs). A significantly higher number of rear-end conflicts occur at the downstream of intersections compared to the upstream section. The curbside lanes with a higher proportion of smaller vehicles observe more rear-end conflicts than medianside lanes. Different vehicle classes with varying lateral movements affect vehicle following time, resulting in constantly changing leaderfollower pairs and a high probability of rear-end conflicts. Dynamic parameters such as speed, acceleration, and spacing maintained by the following vehicles offer detailed insights into identifying conflicting interactions. Finally, rear-end conflict and crash probability at different study locations and vehicle classes is determined using the peak over threshold approach of extreme value theory. [ABSTRACT FROM AUTHOR]

Pedestrian crossing activity at unmarked crosswalks on urban roads in developing countries like India is a common phenomenon. Pedestrians used to cross the road at their place of interest to access residential and commercial land use. Such crossing operations cause a twofold effect: first the pedestrian put themselves at high risk of collision with the moving traffic, and they also affect the normal traffic operations, which causes excessive delay to vehicular traffic. Available pedestrian crossing warrants (PCWs) based on PV2 (where P is the volume of crossing pedestrians per hour and Vis per-hourly traffic volume) focus on the safe movement of pedestrians, but traffic operation is least considered in such warrants. The present study deals with the development of pedestrian crossing facility warrants based on pedestrian safe movement along with vehicular delay, which includes traffic efficiency as well. The traffic data collected from four different locations through the videographic survey were used for evaluating the delay for the individual vehicle due to pedestrian crossing activity. The delay thus evaluated was further validated using the probe vehicle data collected during the same observation period. The vehicle was fitted with the GPS-based performance box instrument that provides the vehicle trajectory at any instance. A significant number of sample data were collected with the probe vehicle and delay was determined using trajectory data. The finding of the delay obtained from the field data was validated incorporating a simulation-based analysis to resemble the interaction of pedestrian flow dynamics with vehicular flows. The crossing behavior of pedestrians was simulated using microscopic simulation software VISSIM. The microsimulation model was first calibrated and validated for field traffic conditions. The total delay was assessed for the traffic stream, and it was found to follow a second-degree polynomial relationship with PV2 values. The clustering analysis was carried out using K-means clustering to define a threshold value for pedestrian crossing facilities. These warrants were also identified based on PV2 utilizing the relationship between total delay and PV2 values. The results of the present study will be useful for practicing engineers for designing pedestrian crossing facilities considering pedestrian safety and vehicular operation as well. [ABSTRACT FROM AUTHOR]

The novel Coronavirus (COVID-19) significantly impacts all sectors and brings the whole population to stuck at home due to a countrywide lockdown in India. Due to the lockdown, the major influence is on students and education systems all over the world. The present study attempts to study the effect of COVID-19 on traffic patterns and choice of mode for the students to reach their host institute. The response survey was carried out, and the pre- and post-travel patterns were investigated for the participants. The interesting finding is that irrespective of the income level, parents are more serious about the safety of their child against COVID-19. As the available infrastructure is not adequate to follow the COVID-19 protocol, parents have insisted on using their personalized mode to send their children to school subject to the utmost social distancing norms followed by schools. Policymakers and planners may use the outcome of the present study to see the impact of educational trips [ABSTRACT FROM AUTHOR]

Level-of-service (LOS) is a key index that reflects the operational condition of the toll-plaza. Although it has been observed that the developed countries have a very effective system at the toll plazas; but, the developing countries are still struggling to achieve the properly managed system that could improve the customer satisfaction at toll plazas. Hence, a sample of 1431 respondents has been collected at four toll plazas located in India and analyzed, for users' perceived LOS. The ordered probit model was developed and the results show that humps at tollbooth is a highly influencing variable. The study results reveal that the users not only consider delay but also a multitude of factors such as age, education, experience, frequency, aesthetics etc. while evaluating the users' perceived LOS at toll plazas. The results obtained from the present study portrays that all significant factors need to be considered when planning of toll plazas. [ABSTRACT FROM AUTHOR]

This paper presents a vehicle-type-specific headway distribution analysis at toll plazas under mixed traffic conditions. The aim of the paper is to provide headway distribution models that may be used for traffic flow analysis and traffic management at tollbooths. Seven classes of vehicle and a total of 49 combinations of leader–follower vehicles were considered, out of which 11 combinations were considered for studying the headway distribution model based on the frequency of arrival of such vehicle combinations at tollbooths. The results showed that vehicle classes requiring a headway of 5–25 s followed a log-normal distribution whereas, for higher headway ranges of 15–40 s, the generalised extreme value showed the best fit. For the small car category, the Wakeby distribution showed a better result than conventional distributions. The findings of this study may be useful for developing toll plaza microscopic simulation models, which could be used for assessing and improving the performance and efficiency of tollbooths. [ABSTRACT FROM AUTHOR]

For proper planning, design and operation of an electronic highway toll facility, the capacity of the toll lane is an important aspect that needs to be considered. Although the capacities of roads and intersections are generally referred to as stochastic in nature, toll lane capacity is still considered as a deterministic value. A study was undertaken into the variation in service headway and thus reliability related to capacity values for toll lanes. Videographic traffic data were collected at three electronic toll plazas in India. The service headway of cars was found to be lower compared to vehicles with trailers. A Monte Carlo simulation was used to generate the different variations that may occur in the service headway owing to supply-side and demand-side changes. Finally, the capacity for 80%, 90% and 95% reliability was found as 494, 554 and 608 passenger cars per hour, respectively. The developed capacity values can be used to check the volume-to-capacity ratio in a mixed traffic lane and can be used to develop the level-of-service thresholds for electronic toll collection lanes in future studies. [ABSTRACT FROM AUTHOR]

Pedestrian crossing at undesignated midblock locations is a prevalent phenomenon in developing countries like India that adversely affects the traffic performance of such sections. The present study aims to determine the effect of such pedestrian crossings on traffic characteristics like vehicular speed and capacity of the section. Data was collected on six-lane urban arterial midblock sections in six different metropolitan cities in India. Fifteen such sections were selected, with and without the presence of crossing pedestrians, and named base and friction sections, respectively. Speed models were developed for the sections, and from the speed models, the capacity of base and friction sections was estimated with varying pedestrian crossflow. The model capacity values were further validated by collecting field data at six more sections--three base sections and three friction sections. The model capacity values were in good agreement with the field capacity values, with mean absolute percentage error (MAPE) values less than 6% for both data sets, that is, for base and friction sections, respectively. [ABSTRACT FROM AUTHOR]