Level Exits and Level Entrances

In LEGION Model Builder, the role that Level Exits and Level Entrances played in earlier versions has largely been incorporated by the new Stair and Escalator objects, which now handle the movement of Entities from one level of a model to another.

However, they remain available for the modelling of lifts and in case you need to create an ad-hoc stair or escalator if for any reason you find that the specialised objects do not fulfil your requirements.

You must always create Level Exits and Level Entrances as pairs. First, place the Level Exit in the area where Entities will leave one level of the site and place the Level Entrance in the corresponding area of the other level of the site. A Level Entrance can only receive Entities from its paired Level Exit.

In your model, the ‘area of transfer’ between levels must be represented twice: once for the Level Exit and once for the Level Entrance. Level Exits (and paired Level Entrances) should, if possible, be at least 5m long in the direction of Entity travel and any obstacles that appear in a Level Entrance must also appear in the paired Level Exit.

Obstacles directly behind Level Exits should, where possible, be removed because they are detected by an Entity and artificially influence their approach towards the (Level) Exit.

The following example illustrates a staircase between two floors of a building (the stair has three flights). The left-hand illustration is of the original architectural CAD plan, the right-hand illustration is of ‘cleaned CAD’ and features a red Level Exit and a green Level Entrance.

The architectural drawing of Level 1 shows the second flight of stairs cut-off, for illustrative purposes. The Level 2 drawing shows both the second and third flight of stairs in full: as a person would see them if viewing from a great height.

The logical place to locate the Level Exit/Level Entrance pair is on the second flight of stairs because it appears in both Level 1 and Level 2 plans. The Level 1 drawing of the second flight will need to be extended to match the Level 2 drawing. The Level Exit and Level Entrance can then be placed. The obstacles that appear in a Level Entrance match those in the paired Level Exit.

Congestion

If a Level Entrance is located in an area that becomes congested, Entities will not pass through the Level Exit until there is sufficient space for them in the Level Entrance.

Movement from a Level Exit to a Level Entrance is one-way. Once an Entity has passed from a Level Exit into the Level Entrance, it cannot pass back into the Level Exit, even if congestion builds up and forces Entities backwards: they will remain in the congested Level Entrance.

Showing Clones

Entities affected by a Level Exit upon their first step into its area immediately appear in the same location inside the paired Level Entrance. This process is referred to as ‘cloning’ and it ensures that the area occupied by Entities that have moved to a different level does not appear to be available for other Entities to move into until the next time-step.

Setting Level Exit parameters

You can draw a Level Exit in the same way as you would a regular Exit but you will be prompted to decide whether you want to use it as a target object (with a Focal Segment) or to allow the object to filter for Entities.

Create as Target or Filtering object? [T]/F

Target is the default setting, so press Enter to create the Level Exit as a target object, or type F and press Enter to create it as an object that filters Entities. You will need to set up slightly different parameters depending on your choice of target of filter object.

To set Level Exit parameters:

Ensure the Edit Level Exit dialog is displayed.
Enter a name for the Level Exit in the 'Name' box (or leave it as it is if you are happy with the existing name).
If the Level Exit doesn’t require an Exit Profile, go to step 5.
To associate the Exit with an Exit Profile, check the box labelled Use exit profile and select a profile from the adjacent drop-down list.
If the Level Exit is a filtering object, you can click on the 'Additional Parameters' tab and enter a value in the box labelled 'Transition Cost'. The higher the value, the higher the perceived cost of using the Level Exit to the Entity. This may assist Entities to choose other less costly means of leaving a level, such as an escalator.
If appropriate, click on the Entity Filter tab and complete all filtering details (see Specifying filter settings for full instructions).
Entities auto-navigate towards the Focal Point of the object if and when they cannot 'see' it due to obstructions. In rare instances this may cause them to move in an unexpected or illogical manner. To remedy this, click to the 'Target Parameters' tab and uncheck 'Use focal point for navigation'.In this case Entities will navigate towards the closest point on the Focal Segment.
If you want to link the Exit to an Availability Profile, click on the ‘Availability’ tab and select an Availability Profile from the drop-down list labelled ‘Time Scope’. If you don’t want to apply conditions, proceed to step 13.
If you want to apply conditions to the Availability Profile, check the box labelled ‘use condition’.
Select an option from the left-hand drop-down list:
- AND – the condition will apply only when the ‘Time scope’ settings and the conditional settings are both ‘true’.
- OR – the condition will apply when either the ‘Time scope’ settings or the conditional settings are ‘true’.
The OR option is useful in cases where, for example, you may wish to allow a higher number of Entities out of an exit when an unforeseeable instance of high density occurs at a time not covered by the Availability Profile.
Set up your condition as described from step 4 of "To set up a Condition:" in Setting up Conditions .
If you wish to apply any restrictions to the condition, click on the ‘Availability’ tab again and enter values for the following restrictions (details in Restrictions ):
- Time before action
- Minimum activity period
- Maximum activity period
- Minimum time between Actions
Click OK to save the parameters.

Setting Level Entrance parameters

You can draw a Level Entrance in the same way as you would a regular Entrance, except you can’t add Entity Supplies or Arrival Profiles. You are, however, required to select the Level Exit with which it is paired.

To set Level Entrance parameters:

Ensure the Edit Level Entrance dialog is displayed.
Enter a name for the Level Entrance in the 'Name' box (or leave it as it is if you are happy with the existing name).
Select the correct ‘paired’ Level Exit from the Level Exit drop-down menu.
Tick the box named Make size and shape consistent with level exit.
Click OK to save the parameters.