Market Analysis Module (MAM): The
objective of this module is to obtain the sensitivity of the railway's customer
to different market parameters such as reliability and price. A Shipper Survey
was conducted, as a part of the LRDSS, to find out the weights given to
different service parameters by the customers. The results of the survey were
used to develop a model to simulate the mode choice behavior of customer with
respect to changes in transit time, reliability of service and availability of
wagons. The GIS based User Interface provides the User with the facility to
modify key parameters in a seamless manner and analyze their impact on mode
share for different commodities and over different leads.
The Market
Analysis Module can be used to test the impact of service improvements on the
mode share of rail. By running the Market Analysis Module for each key year,
each commodity and a set of assumptions, a matrix of modal share percentages is
arrived at for pairs of Origin-Destination points. This matrix is then used by
TFM to determine the rail demand in total transport as well as corridor wise
market share.
Maps of the type shown above are extremely useful to
assess the impact of strategic initiatives on the corridor wise market share of
railways. This power of presentation enables the user to gauge how the market
share changes with changes in various service parameters such as reliability,
tariffs etc.
Facility Performance Module (FPM): This module uses a sophisticated simulation
model called RAILS to simulate the train running on a section and evaluates
impact of different locomotives and wagon, track conditions like gradients,
signaling system etc. on the performance of a section. By using this model, the
impact of various investment options can be analyzed at a micro level.
In
the LRDSS, FPM is used to generate mathematical congestion functions that relate
technology, operating policy and traffic levels with
long-term-line-haul-variable costs. These mathematical functions are obtained
for different types of trains running on different types of sections over the
Indian Railways. Long-term line haul variable cost consists of line haul costs
of traction, repairs and maintenance of rolling stock, signaling and track costs
and other transportation costs that are congestion dependent. The cost function
and the simulated capacity for a section are used by the Traffic Assignment
Module to capture the ability of the network to carry traffic.
Simulation
modeling is a complex and time consuming exercise and therefore this model forms
a cold link with the GIS front end. However, the results of simulation studies
reside at the back end so that the user can assess those through the GIS. The
User Interface at the front of the FPM Module can be used to generate congestion
graphs for different commodities carried over different sections and on
different types of trains. Alternatively, the user can click on a specific
section of the railways and obtain the cost curve depicting the carrying cost
for different commodities at different traffic levels.
In the map on the
following page, the user selected Coal of type "A" as the commodity. The Cost of
carrying Coal-A in three different types of sections- Flat (Type 6), Rolling
Gradient (Type 10) and mountainous (Type 3) and at different levels of traffic
is depicted in the graphical window. This graph has been generated by the user
making a selection in the window at the lower left corner of the map.
The
red lines in the main map depict movement of Coal-A over the Indian Railways
network.
The user can also generate, by clicking on a section and
requesting for all-commodity line haul cost, a series of congestion curves for
different commodities moving over a single section using the GIS
Interface.
Traffic Assignment Module (TAM): This module forms the core of
the LRDSS and assigns traffic flows over the Railways network based on the
capacity and congestion levels as generated from the FPM, (the supply side) and
traffic forecasts available from the TFM (the demand side).
The Traffic
Assignment Module uses an Operation Research based non-linear programming
algorithm called the Freight Network Equilibrium model. The objective function
is the minimization of the carrier cost i.e. the Railways while assigning
traffic over the entire network. As is the case with other modules, the TAM too
resides in the back end. ArcView is used to manage the databases, edit spatial
data (e.g. add a new line) as well as attribute data (e.g. double a railway line
from single track to double track, or upgrade the signaling system) and display
inputs and outputs of the LRDSS. The TAM Module takes care of
- Shortest Path Generator
- Physical to logical networks Generator
- Traffic Assignment
One of the most difficult tasks encountered in
the pre-TAM process is the preparation of the right set of paths that connect
O-D pairs. Quite often, due to exigencies of operations, the preferred path used
by Railways for moving traffic from an Origin to a Destination is not the
shortest path. Under these conditions, the shortest paths generated by an
algorithm such as "K-Short" do not replicate the actual reality and therefore,
the paths have to be manually generated. A typical path may consist of nearly
100 to 200 sections and it is humanly impossible to code these without the
assistance of a GIS.
As a solution to this, a Path Editor was written in
Avenue Script. The user simply clicks on a set of stations that must form a part
of the preferred route. Once this is done, the preferred path between the Origin
and the Destination is automatically appended to the path set generated by the
K-Short algorithm. The Path Editor also has the facility to generate maps with
the full set of paths that connect an origin-destination.
The map above
depicts the use of the Path Editor in which the user has selected six pairs of
Origin -Destination Traffic Analysis Zones and wishes to display the route that
connects these three Origin Destinations pairs. Depiction of the path sets in
the manner described above enables the planner to better appreciate the
currently preferred route apart from making him aware of the other alternative
paths available. The Path Editor also helps the planner to understand the
implications of routing traffic over preferred paths instead of the shortest
paths and throws up interesting possibilities for cost reduction. For example,
zooming in on the previous map helped focus on why the preferred path between
148D and 148P has to be longer than the shortest path. Analysis of the shortest
path helped to emphasize the need to undertake gauge conversion on the
highlighted part of the shortest route. (See map below)
The TAM, while
minimizing the cost of carrying freight, assigns the commodity wise traffic over
the entire Indian Railways Network. A typical TAM run takes over 8 to 10 hours
of preparatory work followed by 4 to 5 hours of computer run and 2 to 3 hours of
post proces sing. Broadly, a single run of TAM implies the following inputs:
- A network comprising of about 1000 nodes and 2000 sections with a cost
congestion function attach to each.
- A Traffic Forecast matrix of the size: 800 originating Traffic Analysis
Zones by 800 Destination Traffic Analysis Zones (TAZ) by 10 commodities
- Approximately 15000 path sets detailing the potential paths that connect the
various origin and destination TAZs.