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• Exploring Input Dataset
It is useful to understand the spatial and attribute relationships of the individual objects in the landscape and the relationships between them. To
understand these relationships, it needs to explore the data.
• Performing Analysis
At this stage, it needs to identify the tools used to build the overall model. In ArcGIS Spatial Analysis provides a wide variety of tools to serve
this purpose. In CNG pipeline case, it may need to identify the tools necessary to select and weight certain land used types, buffer housing, building, utilities
and roads, and weight them appropriately.
• Verifying the Model Result
Check the result from the model in the field. Do certain parameters need to change to give a better result?
• Implementing the Result
Once the spatial problem already solved, verifying that the result from a particular model meets the initial expectations outlined in state the problem,
and then implement the result.
3.2.3.1. Data Preparation
Busway corridor is a vector line that connects the beginning and ending of a bus traveling with a potential point for SPBG. The base maps are collected data
such as utilities, public services, roads, houses, etc. While gas sources is an existing gas main pipe with a potential point to be branched to SPBG. Figure 6
displays the data preparation process.
21 Figure 6. Data Preparation
Pipeline data is relatively simple such as centerlines and value, but the surrounding data that determines its location can be more complex such as
proximity analysis criteria. Thereby, the entire data required are as listed below: 1. Jakarta base maps were collected from BIOTROP Training and
Information Centre BTIC and MIT program that include utilities, public services, roads network, buildings, and houses. Then, it was processed to
calculate information that quite difficult or even impossible to collect, such as proximity, and density.
2. Existing gas main pipe that were collected from PT. PGN Perusahaan Gas Negara Tbk.
3. Corridor VII of the Transjakarta Busway Route that was collected from BP Transjakarta.
4. While the decision criteria and alternatives were based on expert
interpretation and judgment that were acquired from interview. 3.2.3.2. Procedure
The procedure that was performed in this research consists of spatial analysis, rating method and analytical hierarchy process.
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a Spatial Analysis
Spatial Analysis is able to perform cell-based raster analysis. Of the two main types of GIS data raster and vector, the raster data structure provides the
most comprehensive modeling environment for spatial analysis. In general terms, a model is a representation of reality. Due to the inherent
complexity of the world and the interactions in it, models are created as a simplified, manageable view of reality. Models help you understand, describe, or
predict how things work in the real world. There are two main types of model: • Representation models
Representation models try to describe the objects in a landscape, for example, buildings, roads, or utilities. The way representation models are created
in a geographic information system GIS is through a set of data layers. For Spatial Analysis, these data layers will be either raster or feature data. Raster
layers are represented by a rectangular mesh or grid, and each location in each layer is represented by a grid cell, which has a value. Cells from various layers
stack on top of each other, describing many attributes of each location. The representation model attempts to capture the spatial relationships
within an object for example, the shape of a building and between the other objects in the landscape for example, the distribution of buildings. Along with
establishing the spatial relationships, the GIS representation model is also able to model the attributes of the objects for example, who owns each building.
Representation models are sometimes referred to as data models and are considered descriptive models.
• Process models Process models attempt to describe the interaction of the objects that are
modeled in the representation model. The relationships are modeled using spatial analysis tools.
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b Rating Method
The procedure was assigning arbitrary weight to the most important alternatives. Proportionately smaller weights were then given to alternative lower
in the order. The procedure was continued until a score was assigned to the least important alternative. Then the score assigned to the least important attribute was
taken as an anchor point for calculating the ratios. Specifically, the value for the least important alternative was divided by the value for each alternative.
c Analytical Hierarchy Process
Weighting of the criteria was achieved using a portion of the Analytical Hierarchy Process AHP as a systematic method for comparing decision criteria
with a simple equation “Gas Pipeline Route = fSPBG, Route”. The procedure involves mathematically summarizing paired comparisons of the relative
importance of the criteria. The result was applied to perform matrix multiplication with alternative scoring to produce decision score.
3.2.3.3. Required Tools Hardware Requirements
