VISSIM 5.30-05 User Manual

Example 3 - Step 1
1 t = 0 s
x = 5 m
v = 14 km/h
3 t = 1.8 s
x = 0 m
v = 180 km/h
1
3
2
Non-Signalized Intersections
Querverkehrsstörungen
für einen zweistreifigen Kreisverkehr
mit zweistreifiger Zufahrt
Priority rules
for a two-lane roundabout
with a two-lane entry
Spur 1
(lane 1)
Spur 2
(lane 2)
Legende (legend)
t: Zeitlücke
(min. gap time)
x: Weglücke
(min. headway)
v: max. Geschwindigkeit
(max. speed)
gestörter Querschnitt
(stop line)
störender Querschnitt
(conflict marker)
User Manual © PTV AG 2011 267
1-5
2 t = 2.6 s
x = 0 m
v = 180 km/h
At first, priority rules for vehicles entering the roundabout from lane 1 will be
defined. All 3 priority rules mentioned here relate to the same stop line (i.e.
one stop line with 3 conflict markers).
There are different positions, each for time gap and headway to model a
more realistic vehicle flow. Thus a vehicle within the roundabout driving
faster than 14 km/h will not be detected by the headway but only by the time
gap condition. Therefore a vehicle wanting to enter the roundabout can start
to enter even if the one within the roundabout has not left the conflict area
completely. Priority rules 1 and 2 model this behavior - these are valid for all
vehicle classes: No.1 secures the conflict area during slow moving traffic and
congestion within the roundabout; No.2 contains the conditions for normal
traffic conditions (time gap).
Because traffic from the inner lane of the roundabout also affects entering
vehicles of lane 1 an additional priority rule is required (No.3). This one only
needs a small gap time condition, which again is valid for all vehicle classes.