1. “System Simulation/Emulation” As a Decision Making Tool – A Case Study
2003 ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS
November 18, 2003
Karl W. Berger, P.E. DCM, Inc.
Balaji Krishnamurthy Booz Allen Hamilton

2. 2
Overview
•Background
•LFE Concept
•Feasibility Considerations
–Propulsion/Braking System
–Energy Consumption
•Simulation Results
•Emulation Design
•Summary

3. 3
Background – ADA Access to Transit
•Level Boarding
–High-Level platforms
–Wayside lifts
–Vehicle-carried lifts
–Low-Level Platforms with High Blocks
–Low-Floor Vehicles

4. 4
Background – ADA Access to Transit
•Level Boarding
–High-Level platforms
–Wayside lifts
–Vehicle-carried lifts
–Low-Level Platforms with High Blocks
–Low-Floor Vehicles

5. 5
Background – Low Platform/High Blocks & High Floor LRVs
•Floors 40 inches above top of rail.
•Three steps in stair wells.
•Dedicated ADA doorway.
•Separate boarding area (High blocks with ramps).
•Operator intervention typically required.
•1-5 minutes per boarding.

6. 6
•Potential for Improvement
–Eliminate high blocks.
–Reduce operator action, dwell times, etc.
•The “Low Floor” Solution
–12-14 inches Floor height.
–30% - 100% interior Low Floor area.
–Common doorway for all passengers.
–Low Floor LRVs (New Systems/Procurement).
–Low Floor Extensions (Existing systems).
Background – Low Floor Solution

7. 7
LFE Concept
Separate existing A and B carbodies, add Low Floor
section converting existing Single-Articulated LRV to
Double-Articulated LRV. Middle body has low floor.

8. 8
Low Floor Extension Advantages
•Extend life of existing fleet
–Improve vehicle availability
–Renew “aesthetics”
•Increase capacity
–20%-25% passengers
•Economics
–Low-Floor benefits at lower cost
–1/3 cost of new LF LRVs
–Minimal Propulsion modifications

9. 9
LFE Conceptual Design
•LFE body & Articulation adds 30’ length, 22,640 lbs, unpowered truck adds 9,526 lbs
•Same truck spacing – same clearance
•Adds 13 seats and 78 sq. ft. standee space
•Hotel load adds 10 kW
•AW0 142,200 lbs (empty)
•AW1 157,300 lbs (97 pax seated)
•AW2 174,300 lbs (207 pax 3ft²/pax)
•AW3 191,600 lbs (319 pax 1.5ft²/pax)

10. 10
LFE Effects on Existing LRV
•Increase in Length
–Platform, Street running, etc.
–Auxiliary loads (Lighting, HVAC, doors, battery, air compressor)
•Increase in Weight (≈30%)
–Higher duty/reduced performance for Propulsion system
–Effect on Braking capacity
–Energy consumption
–Crashworthiness

11. 11
LFE Feasibility Check – System-wide Issues
•Electrical issues
–Propulsion/braking system capacity
–Energy consumption
–HVAC/Auxiliary electric/Door controls
•Mechanical issues
–Car clearance envelope (vertical curves)
–Crashworthiness (LRV ends and new LFE)
•Operational issues
–Rerailing procedure, System capacity, etc.
–Maintenance issues, Shop limitations, etc.

12. 12
LFE Feasibility Check – System-wide Issues
•Electrical issues
–Propulsion/braking system capacity
–Energy consumption
–HVAC/Auxiliary electric/Door controls
•Mechanical issues
–Car clearance envelope (vertical curves)
–Crashworthiness (LRV ends and new LFE)
•Operational issues
–Rerailing procedure, System capacity, etc.
–Maintenance issues, Shop limitations, etc.

13. 13
LFE Simulation
•TPerf© Software by DCM, Inc.
–Visual Basic, Windows platform
–Data by spreadsheets – visual confirmation
–Rapid data manipulation, “What-If” scenarios
–Numerical integration using Fixed-time step
–Accurate modeling of non-linear relationships
–Accounts for variations in braking rate vs. speed
–Account for grades, curves, train resistance, speed restrictions, propulsion/brake characteristics, etc.
–Outputs include (v, t, S, P) for the track profile

14. 14
LFE Simulation
•TPerf© setup parameters
–11 mile track profile ~ worst grade/curve
–Included street running
–No regeneration ~ worst case
–30-sec station dwell time
–Civil speed regulation:
•Car speed always <= posted speed limits

15. 15
LFE LRV
Car cross area 119 119 Sq. ft.
Car length 120 90 Ft.
Axles 8 6
AW0 141,166 109,000 Lbs.
AW1 157,286 122,020 Lbs.
AW2 174,336 135,660 Lbs.
AW3 191,541 149,610 Lbs.
ERM 9,680 8,184 Lbs.
Initial acceleration 2.34 3.0 MPHPS
Service brake 3.0 3.0 MPHPS
Jerk limit 3.0 3.0 MPHPSPS
Top speed 50 50 MPH
Auxiliary load 50 40 kW
Line length 10.79 10.79 Miles
Stations 16 16
LFE Simulation - TPerf© Input

16. 16
LFE Simulation - TPerf© Input
Brake Blending05,00010,00015,00020,00025,00030,000100,000110,000120,000130,000140,000150,000160,000170,000180,000190,000200,000Car Weight (lbs.) Braking Effort (lbf) Required for 3.0 MPHPS AW0AW1AW2AW3AW0' AW1'AW2' AW3' LRVLFEDynamic Brake Limit

17. 17
LFE Simulation - TPerf© Output
010203040506001020304050607080Time (seconds) Speed (miles per hour) LRV (1-car)LFE (1-car) 25 seconds

18. 18
LFE Simulation - TPerf© Output
4500
4550
4600
4650
4700
4750
4800
4850
AW0 AW1 AW2 AW3
Seconds
LRV 1-Car Train LFE 1-Car Train
Round Trip Time

19. 19
LFE Simulation - TPerf© Output
891011121314050100150200250300350Passengers per Car kWh/Car-Mile LRV 1-Car TrainLFE 1-Car TrainAW0' AW1' AW2' AW3' AW0AW1AW2AW3

20. 20
LFE Simulation vs. Emulation
•Simulation «» software representation
–Permits rapid changes to operating conditions and vehicle design
–Accuracy depends on model detail
•Emulation «» physical representation
–Includes many factors not easily simulated
–Subject to many uncontrolled factors
–Provides operating “feel”
–Lengthy and laborious to modify

21. 21
LFE Emulation
•Temporarily modified propulsion and braking response on a 3-car train:
–Cut out propulsion on middle car
–Dummied in load weight signal to increase Tractive and Braking Effort by 117% in end cars
–Reduced brake response of middle car to 66% of normal
•Emulated LFE propulsion duty cycle for ≈AW2 (166,600)
•Brake rate was matched but friction duty cycle was exceeded due to limitations of test

22. 22
LFE Emulation
Existing LRV Concept LFE Emulation Car length 90 120 270 Ft. Axles 6 8 18 Traction motors 4 4 8 Weight 109,000 166,600 328,000 Lbs. ERM 8,184 9,680 24,552 Lbs. Accel. Mass 117,184 176,280 352,552 TE Max 16,000 18,800 37,600 lbf Acceleration 3.0 2.34 2.34 MPHPS BE Max 16,000 24,100 48,200 lbf Service brake 3.0 3.0 3.0 MPHPS

23. 23
LFE Emulation
•“Reverse engineering” to verify actual propulsion/brake response.
•Developed clear, detailed test procedure.
•Coordination with Safety and Maintenance Departments.
•Test train assembled from revenue cars
•Emulation verified on first on yard track then on nearby level track.
•GPS data logging supported car instrumentation.

24. 24
LFE Emulation
•Operation proceeded smoothly on outbound trip.
–Street running yielded unusable data.
–Good data collected on grade separated right of way.
–GPS provided speed, location, and time.
•Traction motors ran cool.
•Friction brakes overheated on return trip.
•Emulation test cancelled – data collected in normal configuration.

25. 25
LFE Emulation
0
5
10
15
20
25
30
35
40
45
50
0 1 2 3 4 5 6 7 8 9 10
Distance (miles)
Speed (mph)
Actual Run Simulation
Speed versus Distance

26. 26
LFE Emulation
0
5
10
15
20
25
30
35
40
45
50
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Seconds
MPH
Actual Run Simulation
Speed versus Time

27. 27
Summary
•Demonstrated successful use of simulation & emulation as tools in decision making.
•Emulation provided opportunity to better understand existing control functions.
•Emulation was limited by features of existing control system. Could not handle propulsion and braking in the same test setup.
•Simulation does not easily model human judgment.
•Simulation was proven accurate and flexible.