Rail Capacity Workshop

1. Rail Capacity Workshop • Capacity Constraints and Remedies • Curves • Grades • Station stops • Bridges • Diamonds • Track maintenance and renewal SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

2. Curves

3. Y D X Curve Components Spiral • Curve whose degree changes uniformly with distance from origin • Used to: • transition from tangent alignment to curve or between consecutive curves • introduce curve superelevation Circular Curve • Curve of constant degree (radius) • Used to change alignment direction • May connect to tangents or other curves • Introduced by spirals in higher-speed track • Mild curvature: D ≤ 2º • Medium Curvature: 2º < D ≤ 8º • Sharp Curvature: 8º < D ≤ 12º • Extreme Curvature: D ≥ 12º

4. Impacts of Curvature • Restricted train speed • Increased train resistance • 0.08 lb per train ton per curve degree • Affects acceleration time, power requirements • Increased maintenance • Track alignment and elevation • Rail and wheel wear • Greater potential for derailment

5. Curve Forces Direction of curve R R R F F F W W W (a) Speed < Balanced Speed (b) Speed = Balanced Speed (c) Speed > Balanced Speed Relative forces on rails

6. Curve Speed Limit • Vmax = maximum allowable train speed, mph • Ea = outside rail elevation, inches • Eu = allowable cant deficiency, inches • 3 inches for conventional equipment • 4 inches for certified equipment • higher where approved by FRA • D= degree of curve

7. Train Speeds Through Curves (Unconstrained) 4½” superelevation Intermodal Freight Passenger (conventional eqpt.) Passenger (tilt eqpt.)

8. Mitigating Delay due to Curves • Increase curve elevation • FRA maximum for track classes 3-5 is 7 inches • Generally requires spiral length adjustment • Consider effect on clearances, structures, crossings • Provide proper spiral design • Rate of elevation change limits speed • Qualify equipment for greater cant deficiency • Realign track • Reduce curve degree • Reduce number of curves • Extend sidings to reduce length of single track • Reduces meet delay in speed limited territory

9. Vertical Alignment • Consists of grade tangents connected by parabolic vertical curves • Grade tangent has uniform change in elevation over distance (expressed as percent) • Smooth transition between grade tangents provided within length of vertical curve PVI G1 G2 y x PVT PVC L/2 L/2 L

10. Impacts of Grades • Grade force is 20 lb per train ton per percent • Grades can severely affect: • Maximum sustained train speed (upgrade) • Acceleration (upgrade) • Train speed control (downgrade) • Stopping distance • Train buff and draft forces • Curves add resistance and limit speeds, further increasing impact of grades Impact potential of sustained grades: Low G ≤ 0.25% Moderate 0.25% < G ≤ 0.75% High 0.75% < G ≤ 1.5% Very High G> 1.5%

11. Types of Grades • Ruling grade: train with minimum P/W ratio can crest at crawl speed within motive power short-time limits • Momentum grade: train with minimum P/W ratio will crest with some speed reduction from track speed • Helper grade: train gets temporary additional power added to help crest grade • Riprap territory: undulating profile requires care to control buff/draft forces in long trains

12. Reducing Grade Impacts • Raise P/W ratio on freight trains • May increase speeds on ascending grades • Reduce need for capacity consuming helper and doubling operations • Increase power and tonnage on freight trains • Longer trains can reduce train volume, free up slots • Especially useful with distributed power • Avoid stopping train on severe upgrades • Provide operating authority to pass restricting signals at low speed • Provide power switches at sidings

13. Engineering Approaches to Grade Management • Change alignment to reduce grade • Typically involves major capital investment • May increase track length, curvature • Potential complications, delays from R-O-W acquisition, permitting • Tunneling, large cuts can introduce additional maintenance issues • Requires careful assessment of economics • Lengthening vertical curves • Improves train handling • Increases ride comfort at speed

14. Engineering Approaches to Grade Management • Provide multiple main tracks on long grades to permit passes and overtakes of slow trains • Provide auxiliary tracks at top and bottom of grade to: • Clear helper movements • Reduce delay by trains requiring setup/release of retainers • Prevent blockages while doubling • Electrification • Allows increase in train power, regenerative braking • Major capital investment, economics sensitive to fuel prices

15. Each stop requires time for deceleration, station dwell, and acceleration Average train speed decreases as number and spacing of stations increases Close spacing may not permit train to accelerate to track speed between stations Inefficient platform configuration may increase dwell Stopping trains may delay other traffic Through trains may have to slow at stations to reduce risk to passengers Impacts of Station Stops

16. Mitigating Factors for Station Stops • Provide train P/W ratio to achieve performance goals considering desired dwell time and station spacing • Provide for meets and passes at stations where warranted by traffic demands • Sidings • Multiple main track • Optimize platform configuration to minimize dwell time • Adequate length to match access points with demand • High-level fastest loading/unloading SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

17. Operational Impacts of Bridges • Reduced train speed due to bridge design or condition • Restrictions on traction/braking due to bridge design or condition • Equipment restrictions due to bridge design or construction • Restricted train speed approaching movable bridge • Delays imposed by open movable bridges SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

18. Reasons to Speed Restrict Bridge • Bridge condition or structural design inadequate to withstand • Speed related impact loads • Speed related lateral loads • Reduce load effects on critical structures • Remediate track condition defects • Permit train crew verification of movable bridge position • Reduce derailment risk at movable span

19. Movable Bridges • Types • Lift bridge • Bascule (draw) bridge • Swing bridge • Open/close cycle time influences delay • Can be significant capacity constraint with heavy water traffic • More to go wrong than conventional designs

20. Track Crossings Flangeway • Track capacity reduced by crossing movements • Approaching train must be protected against conflicting movement • May limit speed, increase occupancy time • High maintenance location due to impact loading • Problems increase with speed

21. Crossing Improvements • Reduce maintenance requirements • Provide premium components • Replace with One-Way Low Speed (OWLS) design • Replace with turnouts • Improves reliability, operational flexibility • Realignment of track costly, particularly for right-angle crossings • Crossing movements still consume capacity • Provide interlocking with distant signals to reduce approach delay • Automatic-first come, first served • Dispatcher/operator controlled-can prioritize traffic • Grade separate • Costly, uses more real estate • Permanently solves capacity issues

22. Track Maintenance • Railroads must inspect and maintain track • Track must comply with federal Track Safety Standards (49 CFR Part 213) • Track maintenance workers and machinery must be protected from train traffic in accordance with 49 CFR Part 214 • The impact of these requirements on track capacity must be considered SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

23. Inspect track Service and adjust special trackwork and track appliances Replace or repair worn track components Replace failed track components Keep track in proper gage, alignment, and surface Maintain stormwater drainage elements Correct ballast drainage problems Address subgrade problems Control vegetation Manage thermal loads in CWR track Distribute materials for projects Repair storm or derailment damaged track Reconstruct track to higher standards Maintenance Activities

24. Characteristics of track system Rail and rail fasteners Crossties Ballast Track horizontal and vertical alignment Effectiveness of track drainage Nature of track subgrade Traffic volume and mix Maximum train speed Maximum wheel loading Climate Factors Influencing Track Maintenance Needs

25. Speed and Track Condition • Owner sets train speed limits (pax, freight) • Speeds establish federal track class • Track condition must meet requirements for class • If track condition does not meet requirements, owner must take immediate remedial action • Repair • Reduce track class to make defect compliant • Remove track from service

26. Track Classes SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

27. Categories of Defects • Class specific • Defect may become compliant by reducing track class (slow ordering) • Examples: gage, alignment, mismatch • Non-class specific • Defect is non-compliant regardless of track class • Examples: drainage, vegetation • Speed defined • Defect type requires specific limiting speed • Example: rail defect, minimum curve elevation

28. Working under traffic conditions Practical for many types of work Trains may pass through work site while work is in progress Typically requires speed reduction Need to clear on-track equipment adds delay Workers must have protection per Part 214 Taking track out of service Necessary for some times of work May simplify Part 214 compliance Capacity unavailable until work complete Track Maintenance Approaches

29. Mitigating Capacity Impacts • Limit duration of slow orders for defect remediation on main tracks • Address root causes of maintenance problems • Minimize on-track time for forces • Employ hi-rail equipment where practical • Provide nearby clearance location for on-track equipment • Prefabricate track panels and pre-position materials • Use high-production equipment and techniques • Schedule work during off-peak periods • Have close liaison between operations and engineering • Consider need to provide for night work, lower productivity SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

30. Mitigating Maintenance Impacts • Consider life-cycle costs of track components • Premium components can reduce maintenance needs • Include operating cost impacts of maintenance • Employ “blitz” approach • Plan all possible work in zone, perform during shutdown • Design to reduce impacts of maintenance on operations • Increase spacing between main tracks and sidings • Provide crossovers in multiple track territory • Consider maintenance in design of yards and terminals SCORT/TRB Rail Capacity Workshop - Jacksonville Florida