CE 515 Railroad Engineering - Center for Transportation
CE 515 Railroad Engineering Turnouts, Yard Design, & Clearances Arema Ch. 6 “Transportation exists to conquer space and time -” Turnouts • Turns one track into two • Three basic components Switch Closure Curve Frog • Are designated by their frog number http://enwikipedia.or/wiki/Railroad_switch Turnout Design PI Method Equivalent Curve Method • Requivalent= 2(Gage)(Frog Number)2 • Rounded to the nearest 15 • Turnout is place with its beginning/end at the PC/PT of the Equivalent Curve Turnout Construction • Provide the PS and PF for construction • One of three methods – Built in place – Panelization – Hybridization http://www.oerm.org/pages/Turnout_construction_5_27_07_sm.JPG Turnout Speed • Determined by points and closure curve • For curved points, must also consider the point of radius • Self –guarded frogs are usually 15mph limit Arema p. 249 What Does Underbalance Mean? Underbalance is a measure of an adequate level of superelevation for optimal conditions. Because passenger and freight trains have different optimal levels, less than optimal levels are permitted by regulatory agencies, which limits passenger trains from traveling their maximum speed. https://www.nysdot.gov/regional-offices/region1/project-repository/i87MultiModalStudy/documents/draftfinal-highspeedrailsummary-may04.pdf Frog Number • Generally available from No. 6-24+ • Frog angle decreases as turnout number increases • Turnout minimum on most mainline tracks are No. 10 Arema p. 250 Turnout Location • Tandem Leads have a second Turnout immediately after the first Arema p. 252 • Multiple turnouts in a series are called a ladder •Maximum Ladder Angle ∂=Sin-1(S/L) ∂: Deflection angle S: Yard track spacing L: Length of turnout http://www.building-your-model-railroad.com/images/railyard1.jpg Design of Yards • Storage Yard • Local Yards • Flat Switching Classification Yards Torino, Italy http://z.about.com/d/goeurope/1/0/a/Y/torino-railroad.jpg Pueblo, Colorado http://www.airphotona.com/stockimg/images/00200.jpg Flat Switching Classification Yards • • • • Receiving Yard Classification Yard (Hump, Gravity, or Flat) Departure Yard Rip Track http://www.youtube.com/watch?v=XuOZfYMTcx8 Passenger Car Storage Yard • Should be near the terminal Willowbrook Yard, Toronto http://jeffwilk.com/granduncle.php?big=13 Recruiter http://transit.toronto.on.ca/gotransit/2304.shtml Other Design Considerations Administrative buildings Lockers and toilets Equipment storage Fueling and servicing Minor repair facilities Turntables Air compressors Floodlighting Roads Jacking Pads Cleaning stations Wastewater and oil treatment facilities http://www.flickr.com/photos/grundlepuck/151676388/ Clearance The space required between the track and other fixed obstructions, including other track Determined by • Type and Size of locomotive • Type and size of cars • Dimensions of oversize loads http://www.panoramio.com/photo/6355575 Lists and calculation procedures can be found in Arema Chapter 28 Clearance • Side clearance is measured from the center of the track • Must be increased on Curves • Overhead clearance is measured from the above top running rail. http://gritton.org/greg/rail/docs/clearance/AAR_plates_with_UIC.gif Swingout Clearance • Maximum swingout occurs at the mid point of two cars Over hang distance, s, from centerline S=m + w/2 Where, m=R-(2*R-(t/2)*2)1/2 R=Radius of track curve t= truck centers w=railcar width Arema p. 259 Superelevation Clearance e=E*t/G Where, E=superelevation t= height of car G= Gauge distance http://zierke.com/shasta_route/picpages/rb22994.html So e+m is the additional clearance needed Overhead Clearance • Telltales used to be used to warn trainmen on top of the train of an upcoming tunnel http://www.irritatedvowel.com/Railroad/WMRY/JacksMountain/pmb_jacks_mountain_tunnel_telltale_1.jpg Clearances in Iowa • Effective as of last November, close-clearance warning signs must be places where obstructions might impede a person who is lawfully riding on the side of the train. •Dimensions Questions?