Simulation of Multiple Line Rail Sections - IEOR @IIT Bombay ...

ISCI 2012 8
Table 1: Fixed time strategy results
up Headway down Headway Nu Nd W AT Tu W AT Td Direction of 3 rd line
5 5 3.270 5.810 17.403 19.482 up
5 6 3.270 5.273 16.132 18.366 up
6 5 2.727 5.810 17.570 18.442 up
7 5 2.455 5.810 17.948 17.820 down
8 5 2.182 5.810 18.023 17.440 down
9 5 1.909 5.810 18.075 17.221 down
9 8 1.909 4.727 15.000 15.011 up
10 13 1.636 3.909 13.201 13.123 down
10 14 1.636 3.909 13.023 12.921 down
11 7 1.636 5.000 15.590 15.385 down
12 10 1.360 4.180 14.123 14.027 down
13 12 1.360 3.909 13.626 13.508 down
14 13 1.360 3.909 13.428 13.147 down
15 16 1.091 3.636 13.367 13.367 -
16 15 1.091 3.636 13.510 13.266 down
6.2 Variable time
In this strategy, the traffic intensity is calculated every hour. If the traffic intensity is
more than the calculated K and L values(as described in section 6.1) then the direction
of the third line is changed. The underlying assumptions are same as discussed in section
6.1.2. The experimental results for this strategy have been discussed in section 7.2.
7 Experimental Results
7.1 Fixed time strategy
7.1.1 Varying the headway of freight trains
The approach used in the experiments related to table 1 is that, if for certain period of
time we find the up traffic heavier than the down traffic above a threshold, we dynamically
change the direction of the third line from down to up direction (if required). That is we
keep monitoring the values for the traffic and determine the direction of the third line.
(The values obtained in Table 1 are as per the calculations shown in section 6.1.1)
The static allocation of direction for third line, we do a pre-analysis of traffic and fix
a schedule for the third line. Say for example, for half an hour the third line is in up
direction followed by half an hour for which the third line is in down direction, followed
by one hour for which third line can be used in both the directions.
Unscheduled trains are fired for an interval of 1 hour. We can see that the direction
of the third line is changed when the difference between the traffic measures Nd - Nu
becomes as greater than or equal to K we will want to change the direction of the 3 rd
from up to down.
In the table 1 we have not specified the results for all the up headways and down
headways.This is because, as the down head way increases, or the down traffic decreases,
the usage of third line changes from down direction to up direction. However, if we reach
a stage where W AT Tu and W AT Td both are equal, that means even if we further reduce