Interpretation of Road Network using QGIS

Irish Interdisciplinary Journal of Science & Research (IIJSR)
Vol.6, Iss.2, Pages 101-109, April-June 2022
ISSN: 2582-3981 www.iijsr.com
101
Interpretation of Road Network using QGIS
Satheeshkumar S1
, Birundha A2
, Sivabharathi T3
, Subha R4
& Swetha J5
1
Assistant Professor, Department of Information Technology, Vivekanandha College of Technology for Women.
2-5
Student, Department of Information Technology, Vivekanandha College of Technology for Women.
DOI: http://doi.org/10.46759/IIJSR.2022.6214
Copyright © 2022 Satheeshkumar S et al. This is an open access article distributed under the terms of the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Article Received: 17 March 2022 Article Accepted: 23 May 2022 Article Published: 16 June 2022
1. Introduction
The map contains different types of road network in Erode district. There are number of inter district bus
routes operated by the Tamil Nadu State Transport Corporations linking Erode and other prominent towns In
Erode district with places of significance outside the district.
We classified the roads into 5 types such as primary roads, secondary roads, tertiary roads, residential roads
and unclassified roads. Primary roads are the roads which are form the parts of main trunk line System and
they directly connect three or more major cities and metropolitan Areas with a population of at least 1,00000.
Secondary roads are the roads have one or more lanes of traffic in each direction, may or may not be divided,
and usually have at-grade intersections with many other roads and driveways. Tertiary roads are outside urban
areas, tertiary roads are those with low to moderate traffic which link smaller settlements such as villages or
Hamlets. Residential road provide access to properties and through routes within a Residential area. As
secondary connectors they are much less likely to be public transport routes. Unclassified roads are the road
that cannot be given a grade because it is a basic standard. They are those in the least important categories, i.e.
local distributor and access roads.
2. GIS Description
GIS is open source software that has been growing, and the development of sharing an open source
applications in the environmental areas that have some significant benefits, namely the free distribution and
the public availability of code, allowing users customization. The Free and Open Source Software (FOSS) for
GIS application that has several advantages, Where the new applications can be developed under them by
using open-source programming languages, such as Python and different libraries (for instance, QGIS
software, QGIS Application Programming Interface (API) and Qt API are commonly used in the
development of new applications).
ABSTRACT
Road networks are the key element for economic growth in every country. It is essential for project a strategic and sustained expansion and an
adequate maintenance of these networks to guarantee quality connections between the different parts of a geographical territory. Road
enables the supply of goods and services around the world and it connect the people to workplaces, schools, hospitals and some other places
in the geographical area. Road infrastructure improves the effectiveness and efficiency of all the countries and increases the standard living of
people, making their lives easier. In this paper we proposed to design the road network map for Erode district using QGIS (Quantum
Geographic Information System). We identified and classified various type of road network for that particular area. In this map we include
what kind of road network is available and also explained the purpose of the each type of road network.
Keywords: Vector data, QuickOSM, Quick map service, OpenLayers plugin, Printout layer.

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Fig.1. QGIS Mapping Tool
Several GIS applications have been developed in different contexts, such as forest fires, groundwater
vulnerability evaluation, soil erosion, and others, combining different methodologies, making effective and
improving the performance of the computing procedures. This trend was also, allowing the automatization of
technologies and procedures into agriculture practice.
GIS software tools have been used in several studies to create the spatial variables required to predict
agriculture production. The QGIS software is shown in the fig.1.
3. Tools in QGIS
A. Vector Data
(1) Point features
The first thing we need to be realize when talking about the point of features that we describe as a point in GIS
is a matter of opinion, and often dependent on the scale. Let’s look at cities for example. If we have a small
scale map, it may be make a sense to represent a city using a point of feature. However as we can zoom into
the map, moving towards the larger scale, it can make more sense to show the city limits as polygon.
(2) Polygon features
Polygon features are enclosed areas like dams, islands and country boundaries. Like polyline features,
polygons are created from a series for vertices that are connected with a continuous line. However because a
polygon always describes an enclosed area, the first and last vertices should be always at the same place
Polygons are often have shared geometry boundaries that are common with a neighbouring polygon.
Many GIS applications have the capability to ensure that the boundaries of neighbouring polygons exactly
coincide. As with points and polyline, polygons have attributes. The attributes describe each polygon. For
example a dam may have some attributes for depth and water quantity.

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(3) Vector data in layers
Most of the GIS applications group vector features into layers. Features in a layer have same geometry type
(they will all be points) and same kind of attributes (e.g. information about species a tree is for a trees layer) as
shown in the Fig.2.
Fig.2. Vector data
For example if we recorded the positions all the footpaths in a school, we will usually store together on the
computer hard disk and shown in the GIS as single layer. This is convenient because this allows us to hide or
show all of the features for that layer in our GIS application with a single mouse click.
B. Vector Attribute Data
Features are the real world things such as roads, property boundaries, and electrical substation sites. That
feature has a geometry which determines if it is a point, polyline or polygon and attributes which describes it
feature.
(1) Attributes
Attributes form vector features that are stored in a table. A table is like a spreadsheet. Each column in the table
is called as field. These records in the attribute table in GIS as each correspond to one feature. Usually this
information in the attribute table is stored in some kind of databases. The GIS application link the attribute
records with feature geometry so that we can find record in the tables by selecting features on map, and find
features on the map by selecting features in the table. Each field in the attribute tables contains a specific type
of data such as text, numeric or date as shown in the Fig.3. Deciding what attributes to use for the feature
requires some thought and planning.
(2) Single Symbols
If this feature we symbolised without using any attributes table data, it can be drawn in a simple way as shown
in the Fig.4. A GIS application will be normally allow us to set the symbology of a layer using a dialog box. In
this dialog box we can choose colours and symbol styles depending on the geometry type of a layer.

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Fig.3. Attributes
(3) Unique Value Symbols
Sometimes the attributes of features are not numeric, but instead strings are used. ‘String’ is a computer term
meaning a group of letters, numbers and other writing symbols. Strings attributes are often used to classify
things by name. We can tell the GIS Application to give each unique string or number its own colour and
symbol. Road features may have different classes and each drawn in the map view of the GIS with different
colours or symbols. Within the GIS Application we can open/choose to use Unique Value symbology for a
layer. The GIS will scan through all the different string values in the attribute field and build a list of unique
strings or numbers. Each unique value can then be assigned a color and style as in Fig.4.
Fig.4. Categorized symbol
C. Data Capture
There are two key concepts to vector data, namely geometry and attributes. The geometry of a vector feature
describes its shape and position, while the attributes of a vector feature describe its properties such as colour,
size, age etc,. Word processors, spreadsheets and graphics packages are all programs that let us create and edit
digital data. Each type of application saves its data into a particular file format.

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Table 1. Extension of file format
Extension Description
.shp
The geometry of vector features are
stored in this file.
.dbf
The attributes of vector features are
stored in this file.
.shx
This file is an index that helps the
GIS Application to find features
more quickly.
There are a number of different file formats for GIS data, but the most common one is probably the ‘shape
file’. The name is a little odd in that although we call it a shape file (singular), it actually consists of at least
three different files that work together to store our digital vector data, as shown in the table1.
(1) Creating an empty shape file
Once we have planned what features we want to capture into the GIS, and the geometry type and attributes
that each feature should have, we can move on to the next step of creating an empty shape file. The process
usually starts with choosing the ‘new vector layer’ option in our GIS Application and then selecting a
geometry type which means choosing either point, polyline or polygon for the geometry. The shape file
format allows us to store the numeric field information as either a whole number (integer) or a decimal
number (floating point) The final step for creating a shape file is to give it a name and a place on the computer
hard disk where it should be created which is shown in the Fig.5.
Fig.5. Creation of new shape file
D. Map Production
Map production is the process of arranging map elements on a sheet of paper in a way that, even without many
words, the average person can understand what it is all about. Maps are usually produced for presentations

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and reports where the audience or reader is a politician, citizen or a learner with no professional background in
GIS. Because of this, a map has to be effective in communicating spatial information. Common elements of a
map are the title, map body, legend, north arrow, scale bar, acknowledgement, and map border which are
shown in the Fig.6.
Fig.6. Printout layer
(1) Map title
The map title is very important because it is usually the first thing a reader will look at on a map. It can be
compared with a title in a newspaper. It should be short but give the reader a first idea of what the map is
about.
(2) Map Border
The map border is a line that defines exactly the edges of the area shown on the map. When printing a map
with a graticule (which we describe further down), we often find the coordinate information of the graticule
lines along the border lines.
(3) Map Legend
A map is a simplified representation of the real world and map symbols are used to represent real objects.
Without symbols, we wouldn’t understand maps. To ensure that a person can correctly read a map, a map
legend is used to provide a key to all the symbols used on the map. It is like a dictionary that allows us to
understand the meaning of what the map shows. A map legend is usually shown a a little box in a corner of the
map. It contains icons, each of which will represent a type of feature.
(4) North arrow
A north arrow (sometimes also called a compass rose) is a figure displaying the main directions, North, South,
East and West. On a map it is used to indicate the direction of North. For example, in GIS this means that a
house that is located north from a lake can be found on top of the lake on a map. The road in the east will then
be to the right of the water body on the map, a river in the south will be below the water body and if we are
searching for a train station to the west of the lake we will find it on the left side on the map.

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(5) Scale
The scale of a map is the value of a single unit of distance on the map, representing distance in the real world.
The values are shown in map units such as meters, feet or degrees. The scale can be expressed in several ways,
for example, in words, as a ratio or as a graphical scale bar. Expressing a scale in words is a commonly used
method and has the advantage of being easily understood by most map users. Another option is
the representative fraction (RF) method, where both the map distance and the ground distance in the real
world are given in the same map units, as a ratio. A scale expression as a graphic or bar scale is another basic
method of expressing a scale. A bar scale shows measured distances on the map.
4. Methodology
A. Download shape file
First, we had to download the India district boundary map as a shape file with the extension of .shp. The
resources are available in the various website and save it in on our PC. Now we open the QGIS application
which has various panels. Go to browser panel, drag and drop the India district boundary shape file which is
already downloaded. Select the particular district which we plan to design the road network .Crop the
particular area by using clip vector and save it as Working Area in the format of shape file.
B. Import vector data
Install the plugin which are needed such as QuickOSM, Pre-processing plugin. Go to vector and choose
QuickOSM which contains some collected geo-information. In QuickOSM we have to select the layer extent
with selected area. We can send the request for desired information using query with key and value and then it
will return required data. but this information are temporary. To make it permanent, we have to save the layer
in our PC. Otherwise it leads to loss of information By using QuickOSM we import the information about the
road network and crop network for that particular area and save it as Road Network in the format of geo
package.
C. Classification of road network
The layer panel list all the layers in the project and help us to manage their visibility. By using this we can edit
the property, symbols, attribute, and labels and so on of that layer. Select the Road Network layer and right
click on it. Select the properties which contain various features. From that, select symbology in which we can
categorize the different road network by choosing categorized option from the list, After that the road network
had been classified. The categorized networks are shown in the layer panel. We can edit the color, size and
shape of the symbol for each label. We can import the places by using QuickOSM as similar way which is
used to import the road network.
D. Printout layer
After completing the map, we will go to printout layer which present in the project tool. In the print out layer
we can design our map according to our wish. First we have to add the map, then we can add legends which
are used in the map. We edit the format and size of symbol and letters with required space. It is also possible

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to modify the space between the legends. We can include the north arrow to identify the direction and scale to
represent the distance. Finally the designed map and obtain the map either in the format of pdf or image as
shown in the Fig.7.
Fig.7. Shows the Classified road network
5. Conclusion
In this paper, we identified and classified the various road network for erode district using vector data which
can be obtained from QuickOSM. The road networks are categorized into primary roads, secondary roads,
tertiary roads and residential roads by using unique value symbol. The individual colour represents the
individual road type. With the help of printout layer, we add legends in the map to understand the
classification of the road network. In addition to that we include north arrow, scale and grid. We also included
the longitude and latitude for that map. It is common concept in road network planning is the structuring of
roads depending on the function of the road. In network planning transport planners therefore determine the
form of a network not only by adding new network elements but mainly by assigning a function to a road
which then influences the road design.
Declarations
Source of Funding
This research did not receive any grant from funding agencies in the public or not-for-profit sectors.
Consent for publication
Authors declare that they consented for the publication of this research work.
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