Comparison of traffic noise prediction using fhwa and ertc models in gorakhpur city 16 aug

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IJBSTR RESEARCH PAPER VOL 1 [ISSUE 8] AUGUST 2013

Comparison of Traffic Noise Prediction Using FHWA and ERTC Models in Gorakhpur City Swati Tiwari and R. K. Shukla* ABSTRACT-It is a well-known fact that the major contribution to noise pollution is traffic noise. Noise from traffic affects the life of surrounding people especially when the traffic volume and traffic speed are high. The major contribution of vehicular traffic noise problem is various kinds of vehicles like heavy, medium trucks/buses, automobiles and two wheelers. There are many different noise prediction models which have been developed by many western countries. Most of the models are based on L10, Leq and other characteristics.

In India, the transportation sector is growing at a very fast rate as a result there is enormous increase in the vehicular traffic noise. In the present paper modified FHWA model and ERTC model of Thailand are being used for the traffic noise prediction and also a comparative study is being done to check for the suitability for the assessment of traffic noise in the Gorakhpur City. The study reveals that both of the models can be implemented in the assessment of traffic noise in Indian context with a fair degree of accuracy.

The study of observed noise is also done for the assessment of road traffic noise in Gorakhpur city.

KEY WORDS: Traffic noise; L10; Leq; Traffic noise prediction; Traffic noise assessment; FHWA model; ERTC model .

1 INTRODUCTION In the whole world traffic noise has become one of the most widely effective issues in the urban noise pollution, and its effects have aroused wide public concern [1]. Hence, a lot of road traffic noise research and management work have been conducted by scholars and environmental engineers around the world. The most important cause of traffic noise is the number of road vehicles, and consequently, increases in the density of road traffic [2]. In most developed countries and even in many developing nations the construction of multi-lane motorways is going on at increasing rates during last few decades, allowing large volume of traffic to travel at a sustained speed.

Speed of traffic is the next most important cause of noise on the roads. As a general rule, faster the traffic moves, greater is the volume of noise [3]. Traffic noise is one of the principal environmental nuisances in urban areas, have been shown by many surveys conducted in the world, and most of the countries have their own traffic noise prediction model according to the traffic and environmental conditions [4].

Author: Swati Tiwari is currently pursuing master of technology program in environmental engineering in Madan Mohan Malaviya Engineering College Gorakhpur affiliated to Gautam Buddh Technical University Lucknow.

E-mail: swati.tiwari2012@gmail.com *Co-Author: R. K. Shukla is Associate Professor in Civil Engineering Department in Madan Mohan Malaviya Engineering College Gorakhpur affiliated to Gautam Buddh Technical University Lucknow.

E-mail: drshukla_gkp@rediffmail.com

As the road traffic noise prediction for traffic noise assessment and later theoretical basis to carry out governance, the selection of model and the road traffic noise prediction accuracy are particularly important. Based on FHWA (Federal Highway Administration) noise prediction model, countries have developed different predictive models for road traffic noise according to their local actual situation [5].

Prediction models for traffic noise are required as aids in the design of highways and other roads and sometimes in the assessment of existing or envisaged changes in traffic noise conditions. Commonly, they are needed to assess noise levels set by government authorities. Environmental laws require the Environmental Impact Statement (EIS) to take into account the effect of the proposed noise on all existing and potential elements of the environment, besides statutory criteria.

Therefore a call for a variety of descriptors and criteria is needed. Sometimes, special descriptors are required for the assessment of complaints about road traffic noise [6].

It is observed that various traffic noise studies were reported and a number of traffic noise prediction models have been developed, as per reviewed literature.

The study concluded that the accuracy of the ERTC (Environmental Research and Training Centre), model of Thailand is sufficient for practical use and will be used for environmental impact assessment in Thailand. The model has shown that it can be used for 2, 4, 6, 8, and 10 lane highways in cases where speed is between 30 and 140 km/h. The model has shown the accuracy to be within ±3 dB (A) range about 92.3% of the time and that it can predict the road traffic noise

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IJBSTR RESEARCH PAPER VOL 1 [ISSUE 8] AUGUST 2013 level at a distance of 1–80 m, and at a height of 1–12 m from the ground [7].

In the present paper modified FHWA model[8] and ERTC model of Thailand [7] are being used for the traffic noise prediction and also a comparative study is being done to check for the suitability for the assessment of traffic noise in the Gorakhpur City.

2 TRAFFIC NOISE PREDICTION MODELS For the prediction of traffic noise in Gorakhpur City following two models, FHWA and ERTC model of Thailand have been used.

2.1 The modified FHWA model in Indian Context [8] Seven categories has been made for the classification of vehicles and the detailed method has been described here. For each category of vehicle the hourly Leq value is calculated using following formula: Leqi = L0 + Avs + AD + As‌‌‌‌‌‌‌‌‌‌‌‌‌.eqn 1 Where, Leqi = Hourly equivalent noise level for each vehicle type L0 = The reference energy mean emission level AD = Distance correction As = Ground cover correction Avs = Volume and speed correction for subscribe Formulas for prediction of the noise The individual noise emission equations used in the calculation for the prediction of noise levels is given in Table 2[5],„Sâ€&#x; denotes speed of the vehicles in kmph.

Leq=10 logâ Ą [

đ?‘› đ??żđ?‘–/10 ]‌‌‌‌‌‌..eqn 2 đ?‘–=1 10

2.2 The ERTC model of Thailand The Environmental Research and Training Centre (ERTC) of Thailand for environmental impact assessment have developed this model [7]. Vehicles were classified into two groups and the average stationary noise level of each group was then determined by measurement of many vehicles.

The power level of each group was determined by measuring the noise level of running vehicles.

The equivalent sound level „Leqâ€&#x; observed at a certain receiving point is given by, Leq = PWL – 10 log 2ld + Ld + Lg,‌‌‌‌‌eqn 3 [10] Where PWL is A-weighted energy average power level of vehicle, dB(A), l is the distance from a traffic line to receiving point, m, Ld and Lg are the correction value for distance and diffraction attenuation, dB(A), and d is the average distance between front of vehicles, m. d = 1000 Ă— V/Q ‌‌‌‌‌‌‌‌‌eqn 4[11] Where V is the average speed of vehicles, km/h and Q is the traffic volume, Vehicles/h.

The energy power level of vehicles is given by: For large vehicle group: PWL = 75.1 + 20.4 log V. ‌‌‌‌eqn 5[12] For small vehicle group: PWL = 67.8 + 20.4 log V‌‌‌‌. eqn 6[13] For a number of vehiclesthe average power level of mixed type is given as follows: PWL = 67.8 + 20.4 log V + 10 log [(1–a) + 5.37 a] – 10 log 2ld + Ld + Lg, ‌‌‌‌‌‌‌‌‌.eqn 7[14] Where a is the ratio of the large number of vehicles to the total number vehicles. .

2.3 Need of Traffic Noise Prediction in India

Table 2.Individual Noise Emission Equations [9] Calculation of equivalent noise level For each vehicle type (Leqi) is calculated using eqn 1 and then the total hourly Leqvalue and the combined hourly Leq value is calculated by logarithmic summation of hourly Leq value of each category.

There are many different noise prediction models which have been developed by many western countries. Most of the models are based on L10 [15], Leq and other characteristics [16].

In India, the transportation sector is growing at a very fast rate as a result there is enormous increase in the vehicular traffic noise. As a result many problems due to heavy traffic noise is being identified. In India, the traffic noise generated generally exceeds the prescribed levels [17]. Hence, to assess noise levels set by government authorities and in planning and

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IJBSTR RESEARCH PAPER VOL 1 [ISSUE 8] AUGUST 2013 designing of city road networks traffic noise prediction models are needed.

3 STUDY AREAS

4 EVALUATION OF TRAFFIC NOISE For the evaluation of traffic noise in Gorakhpur City following materials and methodology has been used.

4.1 Materials and Methodology

3.1 Site Selection

Methodology of noise level and traffic data collection

In the present work the study is mainly intended to measure the noise levels at major traffic locations in Gorakhpur City, India. Eleven sites have been selected for this study which is depicted in Fig3.1.

The methodology of noise level measurement included measurement of ambient noise, traffic volume and speed at all sampling sites.

Measurement of ambient noise level

Fig 3.1: Plan showing the sampling stations selected in Gorakhpur City 3.2 Schedule of Observation The detailed schedule of observation at various sampling stations is given in Table 1

The collection of noise level in dB (A) for 10 hours duration starting from 8.00 a.m. to 12.00 noon and then 2.00 p.m. to 8.00 p.m. has been done at those sampling stations mentioned in the Table 1.

At 15 second interval the noise levels have been recorded and hence for 10 minute duration, 40 data was recorded with the help of precision noise level meter of make, „Bruel and Kjaer‟, Denmark (2232) and in dB (A) weighting network. The distance from centerline of the road was 10 meters during the sampling process.

Traffic volume Manual calculation of traffic volume was done at the selected observation sites. The recording of total number of vehicles passed in each type, passing in one hour in a single direction has been done in terms of vehicles/hour.

Spot speed measurement The traffic spot speed is generally measured with the help of Doppler Radar Speedometer (DRS).But due to the nonavailability of Doppler Radar Speedometer, manual method of spot speed measurement was done to the present study.

Two points are marked with a known distance (75 meters) on the road at the sampling site. Stop watch was used to measure and recording of the time taken by the vehicle to cross that distance. The distance was divided with the time taken in crossing the distance and the speed in Km/h for each type of vehicle is calculated and recorded for each hour of study.

5 RESULTS AND DISCUSSIONS Based on the calculation of Leq by Observed data and the predicted noise levels by FHWA and ERTC models using above equations (1 to 7) following graphical presentation is presented for the study of suitability of models in Indian context.

Table 1.Schedule of Observation

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IJBSTR RESEARCH PAPER VOL 1 [ISSUE 8] AUGUST 2013 5.1 Comparison of Observed Noise level with Predicted Noise Levels using FHWA and ERTC models A graphical presentation in the form of bar charts indicating observed and predicted noise level values at various sampling stations is shown in Fig 5.1 to Fig 5.11, which shows that the predicted values by FHWA and ERTC models are mostly in close proximity with the observed vehicular traffic noise.

Fig 5.4.Deoria Bypass Sampling Station

Fig 5.1. Kunraghat Sampling Station Fig 5.5.Rustampur Sampling Station

Fig 5.2.Mohaddipur Sampling Station Fig 5.6.Transportnagar Sampling Station

Fig 5.3.Paidlegunj Sampling Station

Fig 5.7.Nausarh Sampling Station

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Fig 5.8.Kasia Road Sampling Station

Fig 5.9.Golghar Sampling Station

5.2 Analysis of observed data and discussions The flow of mixed traffic is observed at all the sampling stations. The sampling stations like Kunraghat, Mohaddipur, Deoria Bypass and Transport Nagar are the locations that facilitate the entry and exit of the population from Gorakhpur city, India towards the residential colonies, semi-urban settlements and rural areas around the city. This is the reason that the number of scooters, motorbikes, cars, jeeps, vans etc. passing through these sampling stations are found to be higher than at other locations. The operative routes of the buses, are Transport Nagar and Rustampur, therefore, the number of buses here are high. Similarly, because of no entry regulations, the number of trucks at Transport Nagar, Rustampur, and Deoria bypass turn is high as compared to other sampling stations. The operative routes of auto rickshaws are Kunraghat, Transport Nagar, Rustampur and Nausarh.

Through Transport Nagar, Deoria Bypass turn and Rustampur, the Light Commercial Vehicles (LCVs) and minibuses are also plying in large numbers due to the specified entry and operative routes through these points. The tractor/trailers are mostly coming from rural areas; the entries at Rustampur, Transport Nagar and Deoria Bypassturn face the largest number of these vehicles.

Generally, the typical Traffic Noise Levels [11] is summarized in Table 3.

Fig 5.10.Gorakhnath Sampling Station

Table 3.Typical Traffic Noise Levels The observed noise level is lying within the range in some cases like, Kunraghat, Paidlegunj, Deoria Bypass and Kasia Road but out of range in the sites like Mohaddipur, Buxipur, Golghar, Gorakhnath and Transport Nagar .Hence noise regulations should be maintained strictly here for the control of traffic noise.

Fig 5.11.Buxipur Sampling Station

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IJBSTR RESEARCH PAPER VOL 1 [ISSUE 8] AUGUST 2013 The complete analysis of data is summarized in Table 4

felt that both of these models will prove to be an immense help in regulation of rules in traffic noise assessment.

7 REFERENCES 1.

2.

3.

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5.

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Table 4.Comparison between FHWA and ERTC models at various Sampling Stations 9.

6 CONCLUSIONS A steep increase in noise levels has been rendered due to large number of high speed vehicles playing on roads which has been possible due to increased traffic volume and congestion near cities and urban dwellings,.

The analysis of data has shown that the observed noise levels at the selected sampling stations in Gorakhpur City is alarmingly high and the steps need to be taken for the control of noise by the prescribed authority. Also by comparing the observed noise levels with the predicted noise levels by FHWA and ERTC models it has been analyzed and concluded that both the models have predicted the traffic noise in Gorakhpur City with a fair degree of accuracy and in future both the models can be implemented in Indian scenario. To control the traffic noise, there striction on traffic flow and speed can be planned especially along the traffic points of cities and urban areas, using the outcome of this study. It is

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