15.3 Switches

Rail-bound vehicles use switches to change their tracks. In contrast to junctions, a switch can guide the vehicles into two directions only.

There are two different types of switches:

Dynamic switches split the railroad track into two tracks leading in two directions. Dynamic switches can be changed during the simulation.
Static switches split the railroad track into two tracks leading in two directions and have the two variants straight and turn. Static switches cannot be changed during the simulation.

Switches may be placed at an arbitrary position on a main track.

Figure 141. Railroad switches

Figure 141 shows the two partner switches 12 and 32. A side track 2 connects the two main tracks 1 and 3.

Elements in UML model

<switch> element

In ASAM OpenDRIVE, switches are represented by the <switch> element within the <railroad> element.

UML class: t_road_railroad_switch
XML tag:   <switch> (Multiplicity: 0..*)

Switches change the tracks for rail-bound vehicles. Switches guide the vehicles into two directions only.

Table 142. Attributes of the <switch> element
Name	Type	Use	Description
`id`	string	required	Unique ID of the switch; preferably an integer number, see uint32_t
`name`	string	required	Unique name of the switch
`position`	e_road_railroad_switch_position	required	Either a switch can be operated (dynamic) or it is in a static position

XML example

<railroad>
    <switch name="ExampleSwitch12" id="12" position="dynamic">
        <mainTrack id="1" s="1.0000000000000000e+01" dir="+"/>
        <sideTrack id="2" s="0.0000000000000000e+00" dir="+"/>
        <partner name="ExampleSwitch32" id="32"/>
    </switch>
</railroad>

Rules

The following rules apply to switches:

A switch may be either dynamic or static.

Related topics

Section 15.2, "Railroad tracks"
Section 15.3.1, “Main track”
Section 15.3.2, “Side track”
Section 15.3.3, “Partner switches”

15.3.1 Main track

A main track represents the main course for rail bound traffic. A main track has the same properties as a side track. The two track types have been implemented as a convenience function to simplify the modeling of tracks entering and coming out of switches. Figure 141 shows a main track.

Elements in UML model

<mainTrack> element

In ASAM OpenDRIVE, main tracks are represented by the <mainTrack> element within the <switch> element.

UML class: t_road_railroad_switch_mainTrack
XML tag:   <mainTrack>

Main tracks form the primary course for rail bound traffic.

Table 143. Attributes of the <mainTrack> element
Name	Type	Use	Unit	Description
`dir`	e_elementDir	required		direction, relative to the s-direction, on the main track for entering the side track via the switch
`id`	string	required		Unique ID of the main track, that is, the `<road>` element. Must be consistent with parent containing this `<railroad>` element.
`s`	t_grEqZero	required	m	s-coordinate of the switch, that is, the point where main track and side track meet

Rules

The following rules apply to main tracks:

asam.net:xodr:1.7.0:road.railroad.switch.check_switch_conn: Main tracks shall not be used to connect two switches.

Related topics

Section 15.3.2, “Side track”
Section 15.3.3, “Partner switches”

15.3.2 Side track

A side track connects two switches that are placed on main tracks. A side track has the same properties as a main track. The two track types have been implemented as convenience function to simplify the modeling of tracks entering and coming out of switches.

Figure 141 shows a side track.

Elements in UML model

<sideTrack> element

In ASAM OpenDRIVE, side tracks are represented by the <sideTrack> element within the <switch> element.

UML class: t_road_railroad_switch_sideTrack
XML tag:   <sideTrack>

Side tracks connect two switches that are placed on main tracks.

Table 144. Attributes of the <sideTrack> element
Name	Type	Use	Unit	Description
`dir`	e_elementDir	required		direction, relative to the s-direction, on the side track for after entering it via the switch
`id`	string	required		Unique ID of the side track, that is, the `<road>` element
`s`	t_grEqZero	required	m	s-coordinate of the switch on the side track

Rules

The following rules apply to side tracks:

Side tracks shall be used to link two switches only.

Related topics

Section 15.3.1, “Main track”
Section 15.3.3, “Partner switches”

15.3.3 Partner switches

For convenience reasons, two switches may be declared partner switches. This describes a connection between two switches that are linked by a side track. These two switches need to be set consistently. Figure 141 shows the partner switches 12 and 32.

Elements in UML model

<partner> element

In ASAM OpenDRIVE, partner switches are represented by the <partner> element within the <switch> element.

UML class: t_road_railroad_switch_partner
XML tag:   <partner> (Multiplicity: 0..1)

Partner switches are two consistently set switches linked by a side track.

Table 145. Attributes of the <partner> element
Name	Type	Use	Description
`id`	string	required	Unique ID of the partner switch
`name`	string	optional	Unique name of the partner switch

Rules

The following rules apply to partner switches:

Partner switches shall be used to indicate that a side track links two switches.

asam.net:xodr:1.7.0:road.railroad.switch.single_switch_no_partner: Single switches do not have partner switches.

Related topics

Section 15.3.1, “Main track”
Section 15.3.2, “Side track”