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located routes, these information might be integrated within the trajectories
to support dispatching components to find good solutions. Delay detection
can be performed by these components as well, because delays are considered
train wise.
With respect to parallelism the detection of conflicts is an algorithmic
bottleneck, because the conflict detection has to synchronies all train trajec-
tories to detect occupation overlaps. Also the detection of vehicle circulation,
connecting train links etc. requires the association of several trajectories.
Therefore parallel conflict detection requires advanced and complex process-
ing and synchronization mechanisms, but nevertheless with approaches like
regional division of dispatching areas [5] the conflict detection can be sched-
uled in parallel, too.
3
Modeling Dispatching Systems
Starting from the introduced system architecture point of view, this chapter
presents a formal specification for (microscopic) dispatching systems. Refer-
ring to the introduction, a published timetable
tt
orig
=
dp
0
must be available
as a reference point for dispatching. Within the dispatching and rescheduling
operation
dp
i
is transformed into another plan
dp
i
+1
, called the dispatching
plan. The dispatching plan with the greatest index is the current and valid
one. The domain of an object
o
is denoted as
Dom
(
o
)
Definition 1 ((dispatching system)).
Let
execute
:
void
→
void
be a
function without parameters and return values. Then
DS
=(
CDs, CSs, dp,PPs, < execute >
)
is a dispatching system with a non-empty set
CDs
=
{
cd
1
,
···
,cd
m
}
(
m
≥
1
)
of conflict detection objects (definition 2),
a non-empty set
CSs
=
{
cs
1
,
···
,cs
n
}
(
n
≥
1
) of conflict solving objects (def-
inition 3), a dispatching plan
dp
, a probably empty set
PPs
=
{
pp
1
,
···
,pp
p
}
(
p
≥
0
) of dispatching propagation objects and the
execute
-method.
The
conflict detection
-objects implement the conflict detection function-
ality applied to
dp
. These objects return a set of detected conflicts, which
have to be solved by
conflict solving
-objects, which perform the reschedul-
ing and dispatching activities. These conflict solving objects return a set of
dispatching decisions, which are propagated through
dispatching
-objects and
applied to the current dispatching plan.
The
execute
-method performs the cyclic train detection and dispatching
activities performing the internal dispatching process cycle:
w
hile not terminated do {
(1)
∀
c
=
c
∪
cd.getConflicts
(
dp
);
cd
∈
CDs,c
=
∅
(2)
∀
d
=
d
∪
cs.getDispatchingDecision
(
c
);
cs
∈
CSs,d
=
∅
