Entities get stuck going down stairs when they should be going up.

Question

Hello, 
 Some of the Entities in my model seem to lose track of their destination, getting stuck on stairs or trying to go down those stairs when they should be going up. How can I fix this behaviour? 
 Thank you in advance.

James Stewart · Answer

Hi Pilar, sorry you are experiencing these problems. 
 I have reviewed your model and I can confirm there are 2 main issues with how stairs are used in the model, and a few minor issues. I'll describe these, below. 
 Solving these issues should also improve the evacuate times for this model (this looks like an evacuation model), because the entities will not struggle to use the stairs.. 
 
 Please let us know if you need any further help with modelling stairwells in LEGION. 
 
 Best regards, 
 James Stewart, Principle Software Developer 
 
 Major issues: 
 
 Filtering Stair objects have different directions but overlap in the model. Example is ST 5 #001 and ST 5 #002

Both Stair objects filter for all entities. This will confuse the Simulator. It will try to make entities obey both stairs. 
 Entities will first move in one direction, then the other. The may also transition between different levels in the model. When you look at entities stuck on a stair, they appear to flicker. This is because they are changing level every time step, moving between the stair lower and upper sections in the model. I've attached a video showing this.
 
 4237.Model1_correccion (10.3.0.2)_Base.avi

I believe this is the cause of both problems you repoort: your stuck entities, and entities going the wrong way on Stairs. 
 To fix this , please replace the each pair of up and down Stairs with a single bidirectional Stair . The filters can still be "All". The Simulator knows how to deal with this.

It looks like the model has stairwells (for example, ST 5 #001 and ST 5 #002). Stairwells need specific modelling techniques in LEGION. I have attached a PowerPoint to explain the technique .
 
 8446.Stairwells in LEGION.pptx

Minor issues: 
 
 The overlapping flights do not align (see red circled area in picture above)
 
 This will cause inaccurate entity status - some entities will indicate they are on a Stair flight: some will wrongly indicate they are on flat ground. 
 This problem disappears when the pairs of up/down Stairs are replaced with a single bidirectional Stair.

Accessible Space is "leaking" into areas of the model which I don't believe you want to simulate:

To maximise simulation speed, it's good to ensure all your pedestrian spaces are fully closed. 
 The problem is here: 
 
 Closing the gaps gives this:

James Stewart · Answer

6471.Stairwells in LEGION, detailed walkthrough with examples.pptx 
 Hi Pilar, Kindly review the attached PowerPoint presentation. It is a step-by-step example of creating an evacuation model, covering 4 floors, connected with a single stairwell. 
 Example model, ORA and Simulator Analysis files are attached here. Stair names and CAD text are designed to match the content of the presentation: 
 3264.Model1, stairwell evac demo.zip 
 There is another example model, also. This uses the same CAD and stairs as the evac example, but this time the stair objects are bidirectional . There are no extra stairs, no overlapping stairs 
 The only stair change is stair directions are now bidirectional , rather than simply down . 
 Entities on Floor 4 are sent to the exit on Floor 1 (ground). Entities on Floor 1 (ground) are sent to a Waiting Zone on Floor 4. 
 I removed the PZ on Floor 2 and Floor 3. Populations are reduced to 10 entities in each PZ, to avoid entities moving in opposing directions blocking the stairs. 
 It's a good example how your stairwell models can quickly adapt to bidirectional flow, without add overlapping stairs. 
 1526.Model2, bidirectional stairwell.zip 
 Hopefully this material is helpful. 
 Best regards, James

James Stewart · Answer

Hi Pilar, here's my new example: 
 https://communities.bentley.com/cfs-file/__key/communityserver-discussions-components-files/343697/3301.stairwell-demo.lgm 
 I have created a few new CAD layers for the separated landing areas: 
 
 S-Separated Landings 
 P-Separated Landings - Presenation 
 S-Not-small 
 Stair flight blocking 
 
 S-Separated Landings holds autonativation CAD for the separated landings, and the flights leading to and away from them. 
 P-Separated Landings - Presenation holds presentation CAD for the separated landings (stair treads, hand rails etc.) 
 S-Not-small holds autonativation CAD that is the central pillar of each stairwell. Previously these CAD were on a small object layer, but autonavigation must be aware of these pillar so I moved them to an autonavigation layer. 
 Stair flight blocking is for autonavigation CAD which closes off the ends of stair flights after a split, to prevent entities navigating the wrong way to the stairs. 
 
 The separated landing areas are created by selecting and copy/pasting all the CAD for each stairwell into a new model location, then using the Move to Layer command to ensure presentation and simulation CAD are on their correct layers. I modified some of the copied CAD to remove unnecessary lines around the separated landings, and drew some extra lines to fill in some gaps. The stairwells in the separate landing areas are exactly the same size and shape as the original CAD. 
 I added Seed Points to the separate landing areas, so autonavigation can understand the space in those areas. 
 
 I've labelled each landing in the main model CAD and the separated landings CAD with letters A to E , matching your PPT description of the model. 
 I have also named each stair to show how it connects floors and landings. For example Stair 0u to A , Stair A to 1d , Stair 1u to B , Stair B to 2d etc. These stairs are all up only . But you can switch them to bidirectional or down only should you need to, and they will work correctly for those directions too. 
 
 When you simulate this model everyone should move from floor 0 to floor 4. Some of the larger entities may occassionaly stick for a moment or two when navigating the turns between stairs. This is normal, because these large entities don't have enough room to manoeuvre. The effect only lasts a few seconds. 
 My recommendation is you follow my approach and copy stairwell sections to create separate landing areas for the other stairwells in the model, then follow the stair creation, placement and naming system I've used. With so many flights and landings, it's easy to miss a stair of confuse a location, so a regorous naming system and some CAD labels in the model can be a big help.

Entities get stuck going down stairs when they should be going up.

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