Abstract

The accuracy of measured traffic flow on a roadway largely depends on the correctness of the PCU factors used for converting traffic counts. PCU is the number of passenger cars that are displaced by a single heavy vehicle of a particular type under prevailing roadway, traffic and control conditions. The aim of the present study is to develop more appropriate models for estimating the equivalency units of different vehicle types on multilane highways, considering the limitations of available methods. Estimation of equivalency units for vehicle types is described by developing speed models based on multiple non-linear regression approaches. The equivalency units estimated by using models are found to be realistic and logical under heterogeneous traffic flow conditions. The PCU values estimated by the multiple non-linear regression method are compared with and found to be relatively higher values than the values obtained by the dynamic PCU. The accuracy of the models is checked by comparing the observed values of speed with estimated speeds. The multiple non-linear regression approach is also used for estimating the equivalency units on six-lane divided highways. Results indicate that the proposed methodology can be used for estimation of equivalency units for vehicle types under mixed traffic conditions.

The accuracy of measured traffic flow on a roadway is highly depends on correctness of PCUs used for converting traffic volume. Field data for the present study was collected from the mid-block road sections of different divided multilane highways in India. Video graphic method was used for collecting the field data. PCUs are estimated from the available methods as given in the literature by using traffic flow data observed in the field. Present study describes a modified methodology for estimation of PCU value of subject vehicles that includes the time headway as influencing parameter. The approach used in the present study is inspired from the method of dynamic PCU estimation where a PCU is expressed as the ratio of speed ratio and area ratio of standard cars to the subject vehicle type. Unlike dynamic PCU method, this method includes time headway factor for PCU estimation. The method found more realistic and logical as it provides relatively higher values of PCUs than those obtained from dynamic PCU method. Simulation of traffic flow was also performed through microscopic simulation model VISSIM for generating congestion and for comparing estimated PCU values at the level of maximum traffic volume. The methodology adopted in this study will be extended for development of comprehensive PCU model by including more numbers of influencing factors under varying traffic and roadway conditions.

Rail transportation being the economic means of transportation, the majority of pedestrians rely on them in countries like India. Unlike metro stations, in intercity railway stations exists a wide degree of heterogeneity in pedestrian traffic. Pedestrians walking speed on stairways depends on various factors grouped under pedestrian, infrastructure, and environmental characteristics. Understating pedestrian perception of quality of service on existing facilities provides the planners to incorporate pedestrian bothered factors for comfortable access in the design. In this research work, pedestrian perceived level of service on six different stairways in intercity railway stations was analyzed. The questionnaire survey was adopted to understand the individual pedestrian perception towards the level of service on each stairway. Pedestrian characteristics such as age, education qualification, preference of usage between stairway and escalator, and stairway characteristics such as width, inclination, and side friction significantly affect individual’s perception of the serviceability of a stairway. A regression model was also developed by considering the significant factors affecting the pedestrian's perceived level of service of the stairway. Results of this study help in evaluating a stairway facility and arrive at better planning, design, and management to increase its efficiency. This study also helps in making design policies and guidelines for new stairways for better accessibility.

Utilization of various mineral admixtures in producing mortar decreases the porosity and capillarity, hence improves the durability in opposition to water and competitive solutions. In this research work, Ground Granulated Blast Furnace Slag is used to replace 30 percent, 60 percent, and 70% of ordinary Portland cement (OPC) (GGBFS). Mechanical property (compressive strength) and durability properties (permeability, porosity, and sorptivity) of high-performance concrete (HPC) are tested. Water permeability of M85 is measured using three cell permeability apparatus. Compressive strength, porosity, and sorptivity of the same mixes are also found. According to the test results of HPC, 30% replacement level of GGBFS gives higher compressive strength than 60% and 70% replacement levels of GGBFS. An equation is developed for permeability of HPC based on mechanical strength and porosity. It is found that coefficient of permeability of water for HPC mixes ranges from 5.1 × 10-11 cm/sec to 7.8 × 10-11 cm/sec. It is concluded that 30% GGBFS used in HPC produces less porosity, less permeability, and less sorptivity than compared to other replacement levels.