12.1 Introduction to junctions

Junctions enable the connection of more than two roads.

Four types of junctions exist:

  • Common junctions are junctions with drivable lanes that can overlap and where traffic can cross.

  • Direct junctions are junctions where traffic can change roads but cannot cross other traffic.

  • Virtual junctions are junctions where the main road is not interrupted.

  • Crossings are junctions where traffic cannot change the roads.

Table 54. Usage of the different types of junctions
Use case Overlapping lanes Crossing traffic Changing roads Junction type Alternative junction type

ordinary junctions

yes

yes

yes

common

n/a

junctions with traffic lights

yes

yes

yes

common

n/a

entries and exits

no

no

yes

direct

common (not recommended)

yes

no

yes

if constant elevation: direct, otherwise: common

common

yes

yes

yes

common

n/a (direct not possible)

driveways to parking lots

yes

yes

yes

if constant elevation: virtual, otherwise: common

common

driveways to residential estates

yes

yes

yes

if constant elevation: virtual, otherwise: common

common

slip lanes

no

no

yes

combination of one common and many direct

common

yes

no

yes

if constant elevation: combination of one common and many direct, otherwise: many common

common

railway crossing

yes

yes

no

crossing

common
img
Figure 82. UML class diagram of the Junction class

Figure 82 shows the UML class diagram of the ASAM OpenDRIVE Junction class.

Rules

The following rules apply to junctions: