TRAFFIC FLOW AND ENVIRONMENTAL IMPACT ANALYSIS OF A HIGHWAY CORRIDOR

Abstract

To cope-up with the problem of very high volume of traffic coupled with unprecedented levels of traffic densities on major corridors because of high population growth, the developing countries like India are continuously expanding their networks as well as its capacity at the existing systems. Motorised traffic volume has also increased at a alarming rate, causing excessive environmental degradation and consequent concern. In developed countries ,the environmental impact assessment (EIA) has become an integral part of highway planning and design. But in India the considerations for environmental impact are still in initial stages. Only during seventy's there has been an awakening in India also that the environment is very severely affected due to vehicular traffic operation in addition to the pollution being generated by industries. And as a matter of fact, the capital city of India, New Delhi, is environmentally ranked as the fourth most polluted city of the world. As a consequence, a World-Bank study has chosen India as a casestudy, and University of Roorkee , Roorkee has assisted in producing data for Indian region, which has been documented as a study. The Ministry of Environment and Forest, Government of India has i published Environmental Guidelines for Rail /Road /Highway projects. Indian Roads Congress, New Delhi has also published (IRC 104 - 1988), Guidelines for Environmental Impact Assessment of a Highway Project. Some of the other organizations, like Indian Institutes of Technology, National Research and Development, and Educational Centers, including, University of Roorkee , have made efforts in assessing the noise and air pollution due to highway vehicular traffic. But most of the studies have been confined to assessing the pollution in urban cities in India, like Delhi, Bombay Calcutta and Hyderabad etc. Hence, there is an urgent need to not only assess the pollution levels for urban areas but also to critically analyze them, as well as, develop the guidelines for important regional Highway corridors. The Important Factors Influencing the Environment (a) Traffic flow factors - Traffic generated Noise Pollution, Vehicular Air Pollution and Vibration. (b) Highway factors - Visual Intrusion, Severance, Land Consumption and Change in Land Access. (c) Noise & Air Pollution due to Construction Activities, including Transport infrastructure. The noise and air pollution can be related to the riding quality of the road, traffic volume, traffic speeds, but vibration levels are more difficult to predict. Keeping the above discussions in view, the following objectives, scope and limitations of the work have been planned: The main objectives of the study are given below : (a) Selection of the various locations along the study area i.e. State Highway - 45, between Delhi and Haridwar, which can represent a suitable heavy traffic regional corridor, connecting the National capital to the strategically important Niti-pass. (b) To conduct traffic survey : Both directional classified traffic survey and spot speed measurement of different categories of vehicles, simultaneously. (ii) (c) Noise Level Survey : To record, assess and analyse the noise level variation with the traffic flow. (d) Ambient air quality : To measure and assess the variation of • different gaseous (CO, HC and NOx) and Suspended Particulate Matter (SPM), pollutants with the varying traffic flow and vehicle type and composition. (e) Modelling : To develop the mathematical models for different * traffic flow and environmental pollution parameters. (f) Calibration of the model developed (g) To establish optimum operating conditions of traffic flow and the resulting environmental pollution , to make sure that the pollutants are under safe prescribed limit. Scope and Limitations (a) Though there are a number of environmental pollution parameters like land pollution, water pollution etc., but in the present work only two very predominant parameters viz, air and noise pollutions have been analyzed in relation to operating traffic flow variables. (b) Due to some operating limitations the data collection was carried out for the day time traffic and is representative of the major flow variations. (c) The study was conducted only for mid-block sections of the highway and intersection effects were not included. (d) Only four major air pollutants (CO, HC, NOx & SPM) have been analyzed. To carry-out the research work related to vehicular traffic generated pollution the data collection programme was carried-out as under; (iii) Highway Corridor Identification Delhi - Roorkee - Nitipass (State Highway No. 45) highway is considered to be a very important and strategic road link , as this highway corridor connects the country's capital, New Delhi to Ghaziabad, Meerut, Muzaffarnagar, Roorkee, Haridwar, Rishikesh, and all the important Uttar Pradesh hill stations including Mussoorie, Badrinath etc. , and lastly Nitipass, which is on Indo-China boarder. And hence it has an religeous, tourist and strategic importance. There has been tremendous increase in vehicular traffic volume on this highway, in the last few years. And during festivals (Kumbh) and summer-rush- seasons, the traffic volume (including foreign tourists) is enormously increased. Keeping this in view, this highway was chosen as a study area .between Ghaziabad and Haridwar. (a) Selections of locations Different study locations were selected along the identified highway, on mid-block sections, depending upon the highway geometries, landuse pattern, and vehicular traffic composition and operating conditions. (b) Traffic Volume Survey Classified directional traffic volume count at all the selected locations were carried out. Each vehicle type was recorded separately and manually, on a predesigned proforma with recording at 5 minute interval of time. (c) Speed Survey The spot speed in Kmph, for all the different categories of vehicles was recorded, simultaneously with the volume count, using a. Radar Speedometer. (iv) (d) Noise pollution Survey The noise levels in dB(A) were recorded at an hourly interval at varying distances from the pavement (in horizontal plane), at all the locations. The noise samples were collected for ten minutes at 0.1 dB(A) accuracy. The noise receiver was kept at a height of 1.2m. above the ground level, at perpendicular direction to the traffic flow. (e) Air pollution Survey The air pollution survey was carried out by operating a High Volume Sampler, for eight hours, for assessing the SPM (Suspended Particulate Matter) and NOx (Oxides of Nitrogens) at all the locations. Further,air samples were collected in Air Sample Collection Tubes at hourly interval, which were later analyzed in laboratory, using Gas Chromatograph for assessing the CO (Corbon -monoxides) and HC (Unburnt Hydrocarbons). The collected data were analysed as discussed below; Traffic Flow Noise Analysis The collected data were sorted in a suitable form for analysis. The classified traffic volume was converted into equivalent passenger car units (EPCU) per hour. Spot speed data for all the different categories of vehicles, were used to plot a frequency distribution curve and the fifty percentile speeds for hourly interval, for all class of vehicles were found. The noise sample data were utilized to plot frequency distribution curves and different percentile noise levels and different noise parameters were calculated. A suitable computer program in FORTRAN 77 was also developed for the same purpose. (V) A multi-parameter regression analysis was carried-out using already available computer software packages. The mathematical expressions for predicting different noise-parameters were developed. The traffic flow parameters, viz traffic volume, average traffic flow speed, percentage of heavy vehicles and observer's distance from the centre of the highway, were the important input for developing the model. All the developed models were validated based on their goodness of fit test, sign of the coefficients, R-square values, and estimated errors. Nomograms and three dimensional graphical presentation were developed, using the developed models. Traffic Flow Air Pollution Analysis Based on the literature available, the equations for predicting the vehicular emission factors, for various pollutants viz CO, HC, NOx, etc., and for all the different categories of Indian vehicles, at different speeds, were developed. » Equivalent Pollution Truck Number (EPTN) : To convert the traffic volume in a uniform scale, the concept of EPTN was developed based on the emission factor of a particular type of vehicle and its fifty percentile speed for hourly duration. The hourly traffic volume was converted into QEpTN(x). Prediction of Pollutants : For all the different traffic flow and highway geometric conditions the pollutants, CO, HC, and NOx were predicted. Classified traffic volume, average speeds and other meteorological parameters were used for predicting the pollutants using Gaussian Line Source model. Mathematical equations and graphs were developed using predicted and observed pollutants data. The traffic volume in Q_ ,/HR and EPTN(X) (vi) fifty percentile speed of the traffic flow, were the important input parameters for developing the models. From the data analysis results and developed curves, the important • outcome of the work may be summerised as; - There exists useful correlation between traffic flow and noise pollution and traffic flow and air pollution parameters. - For a regional highway corridor, traffic noise pollution may be considered as a single important environmental pollution parameter for its planning and designing the Environmental Traffic Capacity (ETC), as the observed noise pollution levels were recorded to be much higher, at all the times, than the permissible Indian Standards, whereas the gaseous pollutants concentration were more or less within the permissible limits, except the Suspended Particulate Matter (SPM), which was never found under the permissible limits. - The volume/capacity ratio less than 0.6, for a regional corridor may be considered as environmentally safe, and a suitable conceptual representation has been made in this work. For the prediction of traffic flow related noise-pollution levels and vehicular operation related air-pollution levels, a series of mathematical relationships have been developed as under. Traffic Noise Pollution. Noise pollution analysis and model development were carried-out under two categories namely, Four lane highway and two lane highway. To, predict the traffic noise levels, L10, Leq, L50, etc., for both the categories, requisite models have been developed, taking hourly traffic volume in EPCU, percentage of heavy vehicles, observer's distance from the centre of the pavement and traffic flow (50 (vii) percentile) speed, as the important parameters for model development. These models were validated also using the collected data for the same highway corridor at different locations. Traffic Flow Related Air pollution The analysis was carried-out under three categories, namely, four-lane divided highway, four-lane undivided highway, and two-lane undivided highway for developing the air pollutants (namely CO, HC, NOx, and SPM.) predictive models. Correlations have been developed 3 between the pollutants concentrations in ug/m and the hourly traffic volume in QEpTN(X) for the pollutant, x. And the same traffic volumes were also correlated with the traffic flow (fifty percentile) speed. Correlations between traffic volume in Qr-ppy and the traffic flow (fifty percentile) speed for all the different categories have been developed. The pollutants prediction models were compared with the Gaussian dispersion model. « (