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Analyzing Hybrid Track Configurations Through Design of Experiments Techniques. INFORMS 2012 Samuel L. Sogin, C. Tyler Dick, Yung-Cheng Lai, & Christopher P.L. Barkan. Outline. Overview Previous Findings Design of experiments (DOE) Hybrid track capacity factors Response surface model
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Analyzing Hybrid Track Configurations Through Design of Experiments Techniques INFORMS 2012 Samuel L. Sogin, C. Tyler Dick,Yung-Cheng Lai, & Christopher P.L. Barkan
Outline Overview Previous Findings Design of experiments (DOE) Hybrid track capacity factors Response surface model Preliminary findings Questions
Capacity Upgrade Map One track baseline Siding extensions Fill-in Sidings Increased Capacity Increased Cost Connect Sidings Full Two-Mainline-Track
Single Track Sequence Single Track Baseline B A Siding Extension B A B A Fill-in Sidings Partial Second Track B A A Second Track B
Comparing Single Track & Double Track Double Track • Most delays are caused by overtaking trains or by crossovers movements • Likely that trains will perform close to the minimum run time • Delays can follow a exponential distribution • Speed differential between trains is a major factor by causing more overtaking situations Single Track Most delays are caused by trains taking turns using the single track bottleneck sections Very unlikely that trains will perform close to the minimum run time Delays can follow a log-normal distribution Speed of the passenger train is not a major factor
Freight Train Delay Distributions Double Track Single Track Freight trains interacting with 79 mph passenger trains
Freight Delay Distributions Double Track Freight trains interacting with 79 mph passenger trains Freight trains interacting with 110 mph passenger trains Single Track
DOE – More Information From Less Data • Design of Experiments (DOE): • Statistical tool to systematically determine runs in a experiment design matrix • Gain more information than simply varying 1 factor at a time • Consider 3 factors at low, medium, and high levels • 27 () runs are needed to cover all permutations • (Full Factorial) • Could we gain knowledge of the key drivers of the process without doing all 27 runs? • (Partial Factorial – 16 runs) • Could be used to analyze more factors effecting train performance than typical 2-3 factor analyses
Hybrid Track Response Surface Design 50 runs to test all interactions and curvature factors
Hybrid Track Configurations DOE Full Factorial: 952 Runs JMP Partial Factorial: 50 Runs
Double Track Progression Extend Sidings Alternate Double Track Sections (Alternate) Build In (Split) Build Out (Grouped)
Rail Traffic Controller Developed by Eric Wilson from Berkeley Simulation Software Emulates a dispatcher controlling train movements across a network based on train priority Integrated train performance calculator Inputs: track, signals, trains, and schedule Output: delay, average velocity, on time performance
Route Characteristics • 245 miles long • 10,000 ft. sidings • 10 miles between siding centers (8 miles between turnouts) • 2.0 miles between signals • 2-block, 3-aspect signaling • 1 Origin-Destination Pair • 0% grade & curvature
Train Characteristics • Train schedules are randomized over the 24 hour period • All delays are due to mainline train interactions
Analysis Guide The subsequent analysis shows snapshots of the profiles from the response surface models for both freight and passenger delay Each panel shows the change in delay for each variable 12 panels total Steeper lines indicate the trains are more sensitive to a change in the factor level Parallel lines indicate independent effects Non-parallel lines indicate interaction effects
% Double Track Traffic Level Freight Speed Passenger Speed Grouping % Freight Passenger Delay Freight Delay 50 mph 110 mph 48TPD 75 % Alternate 50% 73%
% Double Track Traffic Level Freight Speed Passenger Speed Grouping % Freight Passenger Delay Freight Delay 45 mph 110 mph 40 TPD 75 % Alternate 50% 60 mph
Freight Speed Passenger Speed Traffic Level % Double Track % Freight Grouping Passenger Delay Freight Delay 45 mph 110 mph 48 TPD 75 % Extend 75% Alternate
Freight Speed Passenger Speed Traffic Level % Double Track % Freight Grouping Passenger Delay Freight Delay 45 mph 110 mph 48 TPD 75 % Extend 75% Split
Freight Speed Passenger Speed Traffic Level % Double Track % Freight Grouping Passenger Delay Freight Delay 45 mph 110 mph 48 TPD 75 % Extend 75% Group
Preliminary Findings • Major Effects • Traffic Level • % Double Track • Freight Train Speed • Minor Effects • Progression strategy • Passenger Train Speed • Traffic Composition • Interesting Results • By being the high priority train, the passenger trains are less sensitive to the identified factors than freight trains • Adding double track improves train delay in a near-linear manner • Progression strategy effect is modest • Priority trains can see significant delay reductions by improving non-priority train speeds
Future Work 23 Refine the response surface model to incorporate only significant terms Validate the model against data not used in fitting the model Analyze the delay distributions to explore the transition from Lognormal to Exponential Expand the ranges covered in the identified factors to improve confidence limits Add resolution to the progression from single to double track while holding some minor variables constant
Questions? Samuel L. Sogin 847-899-2711 ssogin2@illinois.edu