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Comprehensive Guide on Hump Yard Design in Railroad Engineering

This guide provides essential insights into the design and function of hump yards in railroad engineering. It covers key factors to consider, including yard size, resistance, acceleration, impact speed, and safety standards. It outlines general guidelines for hump grades, transition requirements, and switching practices. Additionally, it discusses energy balance equations and energy losses in terms of kinetic energy and other forces affecting operations. This resource combines theoretical principles with practical application for successful hump yard design.

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Comprehensive Guide on Hump Yard Design in Railroad Engineering

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  1. CE 515 Railroad Engineering Hump Yard Design Source: Lecture Notes – CE 353 by RegSouleyrette “Transportation exists to conquer space and time -”

  2. Classification (Hump) Yard Photo: www.bilderberg.org/railways

  3. Factors to Consider • Size of yard (number of tracks/length) • Resistance • Acceleration on grade • Maximum impact speed • Safety

  4. Classification (Hump) Yard Source: Dr. Souleyrette’s Lecture Notes

  5. General Guidelines • Hump grades: 4% (100-200 ft.) • Transition: 1.5% • Switching: 1.2% • Classification track: 0.1-0.5% • Spacing: 14-18 feet on centers • Turnouts: #7-10

  6. Retarders Photo: www.wikipedia.org Photo: www.sigrail.com

  7. Too Much? Source: railpictures.net

  8. Engineering It All • Energy balance equation: KE1 + Y1 = KE2 +Y2 – (MKX + SW + CR + WR + ER) • KE: Kinetic Energy (v2/(2g)) • Y: Elevation head, (ft) • X: Horizontal distance, (ft) • MK: Static rolling resistance, (lb/ton) (typ. 2-18) • SW: Losses due to passing through switch, (ft) (typ. 0.02-0.06) • CR: Curve losses, (ft) (typ. 0.025 ft/º of angle) • WR: Wind loss (air resistance), (ft) (next slide) • ER: Energy extracted by retarders, (ft) (next slide)

  9. Energy Losses • Air resistance (Davis equation): KAV2 * X Wn • Retarders: • Variable, up to 0.11 ft. of head/ft. of retarder • Typical minimum length of 20 ft. • Double if retarders on both rails

  10. Vertical/Horizontal Curves • Vertical Curves • Minimum length (ft.): L = A * C • A: Algebraic difference in grades, % • C: Constant dependent on curve type • C = 15 for hump crest • C = 40 for other crests • C = 60 for sag curves • Horizontal Curves • Maximum of 12.5º

  11. Car Velocity • Consider headway to allow throwing of switches • Vs = Lc + H * Vh Lc • Vs: Velocity at switch • Vh: Velocity at hump (release) • Lc: Length of car (avg. 60 ft.) • H: Headway (typ. 60 ft.) • Coupling velocity of 6 ft/s (4 mph)

  12. Examples • Grade leading to hump = +1.0% • Grade after hump = -3.5% • Min. Length L = A * C • L = (1.0 – (-3.5)) * 15 • L = (4.5) * 15 = 67.5 feet

  13. Examples • Grade after hump = -3.5% • Grade leading to switches = -1.5% • Min. Length L = A * C • L = (-3.5 – (-1.5)) * 60 • L = (-2) * 60 = -120 ft.  120 ft.

  14. Sample Calculations • KEA= v2/(2g) = (7)2/(2*32.2) = 0.76 ft • Elev. Chg. = -X * (%)/100 = -130 * (-3.7)/100 = 4.81 ft • MK loss = X * MK/2000 = 130 * 18/2000 = 1.17 ft • Net = EC – SW – CR – MK = 4.81 – 0 – 0 – 1.17 = 3.64 ft • KEB = KEA + Net = 0.76 + 3.64 = 4.40 ft

  15. Other Calculations • CR = 0.025 * º of central angle • WR: As discussed previously

  16. Side Note: Targets Source: wikipedia.org

  17. Questions?

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