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Site selection for ring road in the Coimbatore smart city using GIS and AHP

Conference Paper · January 2021

DOI: 10.4108/eai.7-12-2021.2314508

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 Site selection for ring road in the Coimbatore smart
city using GIS and AHP

Elangovan K1, Gowtham G2, Pranav Srinidhi B3, Siva Venkatesh Anand S4
{ ela.civil@psgtech.ac.in1, gowthamg@iitk.ac.in2, srinidhipranav@gmail.com3,
sivavenkatshanand@gmail.com4}

Professor, Department of Civil Engineering, PSG College of Technology, Coimbatore, Tamil Nadu,
India1, PhD student, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur,
Uttar Pradesh, India2, M.Tech student, Department of Water Resources & Ocean Engineering, National
Institute of Technology Karnataka, Surathkal, Karnataka, India3, Former undergraduate student,
Department of Civil Engineering, PSG College of Technology, Coimbatore, Tamil Nadu, India.4

Abstract. Urban population of India is increasing day by day. The amount of traffic all
cities are exponentially raising and along with poor traffic planning this leads to a chaos.
In order to develop various cities in India, Smart City Mission was introduced by the
Government of India. One such city is Coimbatore in Tamil Nadu, South India. The
traffic congestion in the city has reached its peak and the number of vehicles coming into
the city has risen. This study aims in proposing a route for a ring road connecting all the
major roads of Coimbatore, which would reduce the traffic coming in to the city. For this
study concept of remote sensing, GIS and AHP have been used. The maps corresponding
to population, land-use land-cover, slope, guideline value, location of roads, schools and
colleges, depth of ground water table for Coimbatore city were prepared. Using the
weightages for different criteria from AHP, Site suitability map was created. From the
site suitability map, inner and outer ring roads were proposed. This article is based on the
undergraduate project done by the authors [1].

Keywords: AHP, GIS, Digitization, Weighted overlay, Ring-road.

1 Introduction

A 'smart city' is an urban region that is highly advanced in terms of overall infrastructure,
sustainable real estate, communications and market viability. In India, under the Smart City
Mission, in the Phase I of the project, 100 smart cities have been proposed. Under this,
Coimbatore city in Tamil Nadu, South India also finds a place. For this increasing population
it is necessary to provide an integrated mobility system. There is a catastrophic increase in the
use of personalised vehicles now-a-days. The increase in the use of personalised mobility and
with increase in trade in the city, the number of vehicles that enter the city is increasing. And
due to lack of interconnectivity between various national and state highways of the city, all the
vehicles that need to travel along that highway should necessarily pass through the heart of the
city. Restrictions are laid by the government bodies restrict the entry of trade vehicles during
the peak hours. This leads to delay in the trade operations. So, if a ring road linking all the
major highways that feed the traffic into the city, is planned then it will reduce the amount of
traffic entering into the city.

ICCAP 2021, December 07-08, Chennai, India

Copyright © 2021 EAI
DOI 10.4108/eai.7-12-2021.2314508
2 Objective

The objective of this study is to select suitable sites for ring road for Coimbatore city
using GIS and AHP.

3 Study area

The study area is Coimbatore Municipal Corporation, Coimbatore district in Tamilnadu.

Located on the banks of the Noyyal River surrounded by the Western Ghats, it is the second
largest city in the state after Chennai and 16th largest urban agglomeration in India.
Coimbatore City was constituted as a Municipality in November 1866 and Upgraded into a
Municipal Corporation in May 1981. It is one of the fastest growing level-II cities in India. It
is often called as the “Manchester of South India” due to its high cotton production and textile
industries. The Coimbatore city corporation is divided into five zones and has 100 wards in
total. The area of the city is 257.04sq.km and the current population (as per Census 2011) is
around sixteen lakhs. Fig: 1 shows the Coimbatore city delimitation map as per Coimbatore
city Municipal Corporation (www.ccmc.gov.in).

Fig: 1 – Coimbatore city delimitation map

4 Methodology

The following flow chart shows the methodology adopted.

 Step 1
•Collection of population, guideline
value and ground water level data
•Collection of ASTER DEM data and
LANDSAT imageries
Step 2
•Preparation of maps corresponding to
Population, Guideline value, Slope,
LULC, Location of roads, schools &
colleges, and location of ground water
level data
Step 3
•Weightage calculation using AHP
Step 4
•Preparation of Site suitability map for
Coimbatore

Step 5
• Proposal of routes for ring road alignment

4.1. Data collected:

 The data that are to be collected was referred from a journal on Ring road alignment
for Thuraiyur using GIS by Subramani. T, et.al.[1]
 The data collected for Coimbatore region includes, the population data, guideline
values for various areas and the depth of ground water table in various bore wells/
dug wells.
 The population data for Coimbatore was obtained from the web portal of Census of
India, www.censusindia.gov.in.
 The guideline value for Coimbatore was obtained from https://tnreginet.gov.in/portal/
 The depth of ground water level was obtained from State Ground and Surface Water
Resources Data Centre, Tharamani, Chennai – 600 113.
 From www.earthexplorer.usgs.gov, the official website of the United States
Geological Survey, the ASTER DEM data and the LANDSAT imageries were
downloaded as GeoTiff. format.
 From Google Maps (https://maps.google.co.in/), the locations of schools, colleges
and national and state highways were obtained.
4.2. Software used:
Throughout the study ArcMap software of version 10.4 from ESRI was used.
5 Digitization of map

Digitization is a procedure in which the raster image formats like .jpeg, .jpg, .png, .tif, etc.
are converted to vector formats in the form of shape files (.shp). Only after the digitization
process, the map can be used for further analysis in ArcMap software. Fig: 2 shows the
digitized Coimbatore Ward map.
5.1. Population map:
Using the Microsoft Excel (.xlx) file that is added to the ArcMap window, the population
map for Coimbatore city was created. In the attribute table, the ward number, area in sq. km
and the population were added. Using the Symbology tool, map corresponding to population
was created. Fig: 3 shows the population map of Coimbatore. The legend gives the number of
people in that area.
5.2. LULC map:
From Band 1 to Band 7 of the LANDSAT Images obtained from the USGS website was
added to the window. By using the Image analysis tool, all the bands were merged to form a
single image.

Fig: 2 – Digitized Coimbatore ward map

Fig: 3 – Population map for Coimbatore

In order to prepare the Land Use Land Cover map, the True Colour Composite was
created by changing the band numbers. In this Red was assigned to Band 4, Green to Band 3
and Blue to Band 2. By this process, any change in the original band numbers can be rectified
and a true colour composite of Coimbatore region was prepared. From this, using Maximum
likelihood classification, the LULC map for Coimbatore was prepared as shown in Fig: 4. The
colour coding in the legend is as per the Bhuvan, National Remote Sensing Centre
recommendations.
5.3. Digital elevation model and slope map:
The Digital Elevation Model (DEM) is a map or a raster image showing the elevation of
the ground surface. This map is very much useful for the studies related to the elevation. It
helps in preparation of slope maps, contour maps, aspect maps, etc. The ASTER DEM data
was merged to a single raster and then using the spatial analyst extension in ArcMap, slope
map for Coimbatore was prepared. Fig: 5 shows the slope map for Coimbatore.

Fig: 4 – LULC Map for Coimbatore

Fig: 5 – Slope Map for Coimbatore

5.4. Road map:
There are five national highways and three state highways that pass through the
Coimbatore city. They are - NH 181 (Mettupalayam Road), NH 948 (Sathy Road), NH 544
(Avinashi Road), Trichy Road, SH 162 (Palldam Kochin Frontier Road), NH 948 (Pollachi
Main Road), SH 167 (Marudamalai Road), SH 164 (Anaikatti Road).
Using the Euclidean distance tool, the Euclidean distance raster have been created, and is
shown in Fig: 6
 Fig: 6 – Euclidean distance for Roads
5.5. Locations of schools and colleges:
From the added XY data containing the locations of schools and colleges, separate raster
images showing the Euclidean distance were created. The Euclidean distance for school is
shown in Fig: 7 and Fig: 8 shows the Euclidean distance for colleges.

Fig: 7 – Euclidean Distance for schools

Fig: 8 – Euclidean distance for colleges

 5.6. Ground water level map:
The added XY data of locations of wells and the depth of ground water level
corresponding to it. Using the Kriging interpolation technique, the surface raster showing the
details of ground water level as a contour map was created. The ground water level map for
Coimbatore is as shown in Fig: 9.

Fig: 9 – Depth of ground water table in Coimbatore

5.7. Guideline value map:
The preparation of Guideline value map for Coimbatore is similar to the groundwater
level map using Kriging technique. The guideline value map for Coimbatore is as shown in
Fig: 10.

Fig: 10 – Guideline value map for Coimbatore

6. Reclassification of maps

Reclassification of maps has been done in order to change the class values into unique
values like 1, 2, 3, 4 and 5. All the maps created have been reclassified as shown in Fig: 11,
12, 13, 14, 15 16, 17 and 18.
Fig: 11 – Reclassified population map

Fig: 12 – Reclassified LULC map

Fig: 13 – Reclassification of slope

 Fig: 14 – Reclassification of road map

Fig: 15 – Reclassification of School map

Fig: 16 – Reclassification of College map

 Fig: 17 – Reclassified Ground water level map

Fig: 18 – Reclassified Guideline value map

7. Weightage calculation using AHP

The Analytical Hierarchy Process (AHP) is used to calculate the weightage that need to
be given to various criteria. This also gives the percentages of influence for the criteria used
for the site suitability map for Coimbatore.
The steps involved in the AHP includes the creation of priority matrix, normalisation
procedure of the priority matrix, formulation of priority vector and checking using consistency
index and consistency ratio.
Table I shows the weightages for various criteria considered after the AHP procedure.
Consistency index, CI = Eqn. 7.1
where, is the maximum Eigen value, which was calculated as 7.680 and n is the
number of criteria considered, here seven criteria were considered. So, n = 7. After
calculation, CI = 0.113.
Consistency Ratio (CR) = CI/RI Eqn. 7.2
 where RI is the Randomness Index, which is specified by Prof. T.L. Saaty[1] in his
research paper. For n = 7, RI = 1.35
So, CR = 0.113/1.35 = 0.08.
As per Prof. T.L. Saaty[2], allowable CR for a n value of 7 is 0.10. Since CR of 0.08 <
0.10 (allowable CR), the judgement made is correct.
Table I: Weightage after AHP
Criteria Weightage
Population 34%
Guideline Value 23%
LULC 20.4%
Slope 9.1%
Location of roads 6.1%
Location of Institutions 4.9%
Location of GWT 2.4%

8 Site suitability map and ring road routes

By making use of the weightages from AHP and with the help of weighted overlay tool
from spatial analyst extension, all the reclassified raster maps can be overlaid for creation of a
site suitability map for Coimbatore. The site suitability map for Coimbatore is shown in Fig:
19.
The cost path technique in ArcMap Tool box provides a great way to find the best route
between the start and end points, in terms of least cost. Using this, two ring roads – Inner ring
road (of 29 km) and Outer Ring Road (of 41 km) were proposed. The view of the inner and
outer ring roads is shown in Fig: 20.

Fig: 19 – Site suitability map of Coimbatore

 Fig: 20 – Proposed Inner and Outer Ring Road

9 Conclusion

In this study, in order to reduce the traffic that drives in to the city and divert them to
other major and minor roads, two ring roads – Inner ring road (29km length) and Outer Ring
Road (41km length) were proposed. For these maps corresponding to population, LULC,
Slope, Guideline value, ground water level, location of schools, colleges and roads were
prepared. Using AHP technique, weights for various criteria were calculated. By the Weighted
overlay technique and using the weights, after redistribution, from AHP, the site suitability
map for Coimbatore was prepared. The cost path technique is very effective in finding the
least cost path between start and end points. Using this technique, both Inner and Outer ring
road routes were proposed, effectively.

10 Abbreviation:

AHP – Analytical Hierarchy Process

ASTER – Advanced Spaceborne Thermal Emission and Reflection Radiometer
CI – Consistency Index
CR – Consistency Ratio
DEM – Digital Elevation Model
ESRI – Environmental Systems Research Institute
Eqn. – Equation
GIS – Geographical Information System
km - kilometre
LULC – Land Use Land Cover
NH – National Highway
RI – Randomness Index
SH – State Highway
sq.km – square kilometre
USGS – United States Geological Survey
 – Maximum Eigen value

11 Acknowledgments

We take immense pleasure and feel happy in expressing our humble gratitude and
thankfulness to our guide, Dr. K. Elangovan, Professor, Department of Civil Engineering,
PSG College of Technology for being the constant source of inspiration for us and guiding us
through the project.
The contributions were done by the following members, G. Gowtham, B. Pranav Srinidhi,
S. Siva Venkatesh Anand, R. Jeevanantham and A. Iyyanar.
Last but not the least; we thank our parents and God for the moral support given to us.

References
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B.E project, Department of Civil Engineering, PSG College of Technology, Coimbatore, India,
2019.
[2] Subramani.T, Elavarasi.N, Priyanka.S. “Ring Road alignment for Thuraiyur using GIS”.
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May – June 2017, pp. 241 – 251.
[3] Saaty.T.L, “The Analytic Hierarchy and Analytic Network Measurement Processes: Applications
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