This document proposes using process algebra to model and analyze emergency evacuation from a multi-story building. It identifies issues to address like evacuation time, congestion points, individual behaviors, and how the situation affects evacuation. The model represents evacuees, places, rescuers, the situation, and their interactions using PEPA processes. Results show plots of stair occupancy over time for different stair widths, people saved by external rescuers over time, evacuation time for various situations, and evacuation time vs external evacuees.

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