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CE 515 Railroad Engineering

CE 515 Railroad Engineering. Hump Yard Design Source: Lecture Notes – CE 353 by Reg Souleyrette. “Transportation exists to conquer space and time -”. Classification (Hump) Yard. Photo: www.bilderberg.org/railways. Factors to Consider. Size of yard (number of tracks/length) Resistance

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CE 515 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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