1. Modeling the Interaction Between Railroad Freight Schedule Adherence and Asset Utilization Yan Dong* Joseph M. Sussman** Carl D. Martland** * Transport Dynamics, Inc. 103 Carnegie Center, Princeton, NJ 08610 ** Department of Civil and Environmental Engineering Massachusetts Institute of Technology October 26, 1998

2. Outline Background Degrees of Schedule Adherence Asset Utilization Simulation Model Case Studies Conclusions

3. Background Recently, an active debate about what kind of operating strategy best fits railroad operating characteristics –scheduled approach –flexible approach –mixed approach Specifically: how schedule adherence affects asset utilization Debate is qualitative as opposed to quantitative Very limited research

4. Degrees of Schedule Adherence -- Three Operating Strategies Schedule-adherence (SCH) –railroad operations are conducted according to the operating plan –run trains according to train schedules Flexible short-run scheduling (FSS) –establish a short-run plan based upon expected traffic and resources –railroad operations are then conducted according to this short-run plan Flexible operation (FLX) –railroad operations are conducted according to traffic –run trains according to traffic volume

5. Degrees of Schedule Adherence -- Three Operating Strategies (cont.)

6. Asset Utilization Trains (# IB & OB trains run, % trains on-time, OB train delays due to lack of power and crew units) Cars (# IB & OB cars, % cars on-time, # cars missed 1st connection) Road crew & power units (# units in and out of terminal, average yard times, # units deadhead in and out) Terminal average yard time Terminal connection performance Terminal processing time Line-haul movement time OD trip time

7. Simulation Model A microscopic discrete event-driven simulation model Simulate detailed network (terminal & line) operations under different operating strategies –detailed movement of car, train, crew, and power unit –utilization of terminal/line capacity, terminal resources, and road crews and power units Internal and external stochasticity are fully considered –traffic & arrival variation, delays by accidents, maintenance, weather, etc. –processing variability in terminal and line-haul movement –flexibility to add terminal resources (inspectors & crews), unscheduled trains, & deadhead in/out road crew and power units

8. Model Input Operating plan Terminal resources and capacity Line capacity Classification terminal block to (bowl) track assignment Classification terminal processing capability Cutoff time Other parameters to specify various internal and external stochasticity

9. Model Assumption SCH –IB arrival reliable but traffic volume variable –fixed starting time to assemble OB trains based on the operating plan FSS –IB arrival & traffic volume between SCH & FLX –predict traffic, crew, and power units, and determine assembling time FLX –IB arrival variable but traffic volume reliable –start to assemble OB trains whenever traffic ready

10. Case Studies Actual data from a Class I railroad Three case studies – terminal – service lane network –area network Each study contains –Base case (e.g., current operating condition) –Sensitivity analysis (e.g., internal/external variables changed to see how they affect asset utilization) –Scenario design and runs (e.g., various operating conditions)

11. Service Lane Network Case Study: Layout

12. Area Network Case Study: Layout

13. Model Execution Time (for simulating one month operation)

14. Terminal Case Study: Base Case Result

15. Terminal Case Study: Scenario Design

16. Area Network Case Study: Base Case Result

18. Conclusions SCH –very reliable customer service –high resource utilization –more resources needed as buffers to recover to the plan FSS –very high resource utilization –very high terminal through put (smallest average yard time) –low operating cost –achievable plan development is an issue FLX –cost saving train operations –can handle traffic increase easily and robust –customer service & resource utilization are concerns

19. Conclusions (cont.)

20. Railroads do not have enough resources and an incentive to apply SCH (even FSS) for all traffic priorities; FSS may not provide good service for high priority traffic; FLX is only appropriate for low priority traffic For high priority traffic such as auto and intermodal traffic, use SCH For medium priority traffic such as general merchandise traffic, use FSS For low priority traffic such as bulk (coal) unit trains, use FLX Applying different operating strategies to different traffic priorities as a strategic tool to differentiate rail freight service For railroads, customer service requirement, their willingness to pay for service, available resources, and capacity are driven factors determining which operating strategies are used