Using Formal Methods to analyze evacuation plan of building.

1. PROBLEM STATEMENT
• To analyse the issues in modeling and analysis
of emergency evacuation of a multi-storey
building using the approach of process
algebra.
• It helps:
– To get the predictive information about the
system design alternatives in the early phase of
building and urban plans.
– The loss of human life can be minimized in the
disastrous situations.

2. DESIGN ISSUES
• The model of the systems must address the
following issues:
– Evacuation time under various assumptions.
– Identification of congestion spots.
– Effect of individual behaviour deviating from the
standard behaviour.
– Effect of dynamic changes in the physical space on
the flow of people.
– Effect of the intensity of situation.

3. PROPOSED MODEL: PROCESSES
• The PEPA (Performance Evaluation Process Algebra)
model for the system consists of following processes:
– Evacuee : The people to be evacuated from the building.
– Places : The occupancy of the various building sections.
– Rescuer : The people within the building that help others
in rescuing.
– Ex-Rescuer : The external help for rescuing evacuees.
– Situation : The nature and impact of situation causing
evacuation.

4. • The evacuee in room or corridor:
– EvcFloorY = Γ.opStairZFX_FY .EvcStairX +
Γ.EvcHurtFY + Γ.EvcWaitFY (1)
• The evacuee in staircase:
– EvcStairX = fYsfX Z.Γ.opStairZFX’_FY.freeStairZX.
EvcStairX ’ + fYsfX_ Z.EvcHurtSFX (2)
• The waiting evacuee:
– EvcWaitFY = come_out.Γ.EvcSaved; (3)
PROPOSED MODEL: PROCESSES

5. • The hurt evacuee:
– EvcHurtFX = fX_got_u.ResHurtFX + ex_fX_got_u.Γ.
EvcSaved + ex_sfX_got_u.ExResHurtSFX +
Γ.EvcHurtFX ; (4)
• The rescuer in room or corridor:
– RescuerX = fX_got_u.ResHurtFX + Γ.RescuerFX +
Γ.EvcFloorX ; (5)
– ResHurtFX = Γ.rhopStairZFX’.ResHurtSFX’; (6)
PROPOSED MODEL: PROCESSES

6. • The rescuer in stairs:
– RescuerSFX = sfX_got_u.ResHurtSFX + Γ.RescuerSFX +
Γ.EvcStairX ; (7)
• The process denitions corresponding to external
help:
– ExRescuer = Γ.break_window.come_out.Γ.ExRescuer +
Γ.break_window.get_in.ex_fX_got_u.Γ.out.Γ.ExRescuer
+ Γ.break_window.get_in.ex_sfX_got_u.ExResHurtSFX ;
(8)
PROPOSED MODEL: PROCESSES

7. • The stairs are occupied and then freed, corresponding
denitions:
– StairXfree = opStairZFX _FY.fYsfX_Z.StairZXop +
rhopStairZ’X.StairZ’Xop; (9)
– StairXop = freeStairZX.StairXfree; (10)
• Situation:
– Situation = Γ.Situation1; (12)
– Situation1 = blow up.Situation1; (13)
– EvcFloorY = Γ.opStairZFX FY.EvcStairX + Γ.EvcHurtFY +
Γ.EvcWaitFY + blow up.Evc; (14)
– Evc = Γ.Evc; (15)
PROPOSED MODEL: PROCESSES

8. – Situation1 = blockSFXA.Situation1; (16)
– StairXfree = opStairZFXFY.fXsfXA.SFXop +
opStairZ’FXFY.fXsfXA.SFXop +
blockSFXZ.SFXZBlock; (17)
– SFXop = freeSFXA.SFXfree + freeSFXB.SFXfree; (18)
– SFXZBlock = Γ.dirChange.SFXZBlock +
freeSFXB.SF4XZBlock; (19)
PROPOSED MODEL: PROCESSES

9. Plot between stair occupancy for different stair widths and time.
RESULTS-I

10. Plot between number of external rescuer and people saved by them within 20
minutes.
RESULTS-II

11. Plot between various situation and evacuation time.
RESULTS-III

12. Plot between evacuation time and no. of external evacuees to evacuate trapped evacuees.
RESULTS-IV