Automotive Maintenance and Repair Shop Expansion

1. Automotive Maintenance and Repair Shop Expansion Presentation by Steve Roberson For CST 5306 Modeling and Simulation

2. Model Building Steps • Define the scope of the model • Define the data to be used in the model • Define any submodels that may be needed to break up the complexity • Build the submodels • Add animation • Run the simulation

3. Step 1Scope - General • 3 bay facility • Appointments scheduled at one location • Appointments made up to three working days in advance – No same day service

4. Step 1Scope - Statistics • Average service calls – 29 per day following a Poisson distribution • 55% schedule for next day, 30% two days in advance and remaining 15% three days in advance • If appointment can’t be scheduled for the requested day, 90% chance will be scheduled for following day • 80% leave vehicles, 20% wait on service • Wait time is service time + 1 hour (allowance factor) • No more than five waiting customers will be scheduled in one day • Standard service times are in a BETA distribution – Actual service times are in a GAMMA distribution

5. Beta Continuous Discrete Erlang Exponential Gamma Johnson Lognormal Normal Poisson Triangular Uniform Weibull Arena Statistical Distributions

6. Step 1Scope - Costs • 24 hours of availability – 3 bays at 8 hours per day • Cost per bay - $45 per hour • Customer charged - $78 per hour base on standard service time • Overtime • Limited to 3 hours extra per day per bay • Charge is $120 per hour per bay • If work not completed by end of day, customer given loaner car at a dealership cost of $35 per day

7. Step 1Scope – Statistics Collected • Daily profit • Daily standard service times • Daily actual service times • Daily overtime • Daily number appointments not completed on time

8. New Modeling Methods • Multiple-way decisions • Sets • Variables and expressions • Submodels • Duplicating entities • Holding entities • Statistics and animation • Terminating or steady-state

9. Step 2Define the Data • Define resources (3 bays) • Define sets • Bay resource set • Customer entity set (customer who waits) • Vehicle entity set (vehicles left for service) • Define variables (15 determined) • Define expressions • Formula to determine inter-arrival time • Formula to determine service time • Formula to determine if customer has to wait for service • Final statistics (costing, overtime, service times and waiting times)

10. Complete Model Step 3Define Submodels

11. Generate Appointment Calls Step 4Build Submodels

12. Make Appointment Step 4Build Submodels

13. Service Activity Step 4Build Submodels

14. Update Performance Variables Step 4Build Submodels

15. Control Logic Step 4Build Submodels

16. Step 4Build Submodels • In Arena, the model can be checked for errors • Errors are flagged to assist with troubleshooting

17. Animated Service Center Step 5Add Animation

18. Step 6Run Simulation • Run simulation • Observe results • Analyze results

19. Model Enhancements

20. Redefining the Scope • Not all jobs done by all bays • Bays 2 & 3 can handle all jobs • Bay 1 can only handle 40% of the jobs • Not all customers arrive at start of day • Some never show up • 60%-70% arrive on time (follows uniform distribution) • Remaining arrive randomly over next two hours

21. Additional Resource Set Sets and Resource Logic

22. Service Activity Model Change

23. Model Change Control Logic

24. Re-run Simulation • Observe results • Analyze results