STISIM Drive (SDL) - I - Intersection
Display an intersection on
the screen. When the intersection event is activated, the intersection that is
drawn will have the same attributes as the roadway that the driver is currently
traversing. In previous versions of STISIM, you specified when the intersection
would be displayed and how far in front of the driver it would appear, but in
STISIM Drive this is no longer the case. Instead, the activation distance is
the location of the intersection. Since the roadway is generated before hand,
there is no longer a need for the look ahead distance but this parameter
remains to keep it compatible with previous versions of the software.
There are several restrictions that you should obey when adding intersections to your scenario. These restrictions are required because the program generates the intersections on the fly and this can cause the intersections to be displayed incorrectly. The restrictions are not major and don't have to be followed, but they will help you to create better looking scenarios that do not include strange anomalies. The restrictions are:
1 - Do not include intersections in horizontal curves. Due to the curvature of the road, this could cause the intersection to come back across the current roadway path and can generate some interesting looking roadways.
2 - Do not include intersections in vertical curvatures. Because of the way the program generates the crowned roadway, shoulder and sideslope, putting an intersection into the roadway when there is vertical curvature can cause the intersection to not be displayed correctly. Therefore wait until after the vertical curvature command is finished before adding an intersection.
3 - Intersections work best when you have the same number of lanes in both directions. This is because the intersections that are drawn are set up with the some road configuration the the driver is currently on.
In addition to these restrictions, STISIM Drive automatically makes all intersections flat. This means that from 50 feet before the intersection to 50 feet past the intersection, there will be no road crown, shoulder sloping, or side sloping. This eliminates several anomalies that can occur because you have a sloped main roadway and sloped intersection trying to combine into a single continuous roadway. In order to flatten the roadway, STISIM Drive adds a new ROAD event 100 feet before the intersection and then transitions from the current road parameters to the flat road parameters over the next 50 feet. Fifty feet after the intersection, STISIM Drive adds an additional ROAD event that transitions the road parameters from flat back to their previous values. Once again this transition occurs over 50 feet. Therefore when viewing the STISIM Drive data file, don't be alarmed if you notice some additional ROAD events in the scenario listing.
EVENT PARAMETERS:
|
PARAMETER 1: |
The type of intersection
that will be displayed. To specify the type of intersection, set parameter 1
to one of the following: 0 - Full intersection
(branching both left and right) |
|
PARAMETER 2: |
Longitudinal distance, in feet, that the intersection is away from the driver when it is first displayed. |
|
PARAMETER 3: |
Flag that tells the
simulation which direction, if any, that the driver may turn the vehicle.
This allows you to control whether or not the driver can turn at
intersections, and therefore the driver must follow the route that you
specified. If the driver tries to turn in a direction that is not allowed,
then the simulation will assume that they ran off the road and issue an off
the road accident response by playing the crash recording and incrementing
the accident counter. For more information on turning, see the Miscellaneous
Information section of this manual. To specify the steering direction option,
set parameter 3 to one of the following: 0 - No turning allowed |
EXAMPLE:
2000,I,0,1000,0,1
This event is generally used
for several reasons. First, it is used in conjunction with the cross traffic (CT) event so that the vehicles have a roadway to
travel on. Second it is used for displaying an intersection at signal lights
and stop signs. Third, it can be used for doing 90 degree turns into the
intersection roadway. Finally, it is used to display general roadways for
things like city streets. The example above displays a full intersection
(option 0) 3000 feet down the road (at 2000 feet the intersection turns on and
is 1000 feet away). The final parameter allows the driver to turn either way
into the intersection.