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.
| 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 |
Figure 82 shows the UML class diagram of the ASAM OpenDRIVE Junction class.
Rules
The following rules apply to junctions:
-
No junctions of any type shall overlap each other.
-
The
<connection>element of a junction of @type="direct" shall not have the @connectingRoad attribute. -
The
<connection>element of a junction of @type="default" or @type="virtual" shall not have the @linkedRoad attribute.