1. CE 515 Railroad Engineering
Turnouts, Yard Design, & Clearances
Arema Ch. 6
“Transportation exists to conquer space and time -”

2. Turnouts Turns one track into two Three basic components Switch
Closure Curve
Frog
Are designated by their frog number
Replace rail when worn out or has defects.
Ties replaced when they fail or can’t support the track.

3. 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

4. Turnout Construction Provide the PS and PF for construction
One of three methods
Built in place
Panelization
Hybridization

5. 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
Maintenance can cause track disturbance.
Try to keep in equilibrium to prevent buckling.
Lay rail at elevated temperature and then lock in place with anchors.
Dynamic stabilizers apply controlled, accurate stabilizing forces into the track structure at continuous speeds of up to 3/4 mph.
Combination of horizontal vibration and a vertical load.
Arema p. 249

6. 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.

7. Frog Number Generally available from No. 6-24+
Frog angle decreases as turnout number increases
Turnout minimum on most
mainline tracks are No. 10
Flange of the wheel tends to crowd the outer rail – results in abrasions which lead to wide gage and formation of defects.
Locomotive on-board lubrication, wayside lubricators, high rail equipped lubricant pump and nozzle system, hand application
Only apply to gage corner of rail – low rail should be lubricated
Other friction modifiers applied to the tread of the rail to optimize coefficient of friction on the running surface of the rail.
Arema p. 250

8. 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)
Used to remove surface imperfections on the rail
∂: Deflection angle
S: Yard track spacing
L: Length of turnout

9. Design of Yards Storage Yard Local Yards
Flat Switching Classification Yards
Torino, Italy
Pueblo, Colorado
Blocks drainage, decreases visibility, fire hazards
Some is desirable for wind breaks, prevent erosion
Herbicide or mechanical cutting for removal

10. Flat Switching Classification Yards
Receiving Yard
Classification Yard (Hump, Gravity, or Flat)
Departure Yard
Rip Track
Many of the commonly applied hwy stabilization methods are applicable to RR. Talk more about this in drainage portion of class.
Flash butt welding: A technique for joining segments of metal rail or pipe in which segments aligned end to end are electronically charged, producing an electric arc that melts and welds the ends of the segments, yielding an exceptionally strong and smooth joint. Also called flash welding.

11. Passenger Car Storage Yard
Should be near the terminal
Willowbrook Yard, Toronto
Production gangs include: Rail, Tie, Undercutting, Surfacing, Road Crossing Renewal, Turnout
Recruiter

12. 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

13. 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
Lists and calculation procedures can be found in Arema Chapter 28
Inspect for internal flaws within the rail.

14. 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.
Geometry cars check basic track geometry and gage compliance. Indicates the problem areas. Can leave paint mark on track. FRA operates one to determine compliance.
GRMS – finds wide gage under loading conditions. FRA permits the data in determining gage compliance in lieu of the required number of non-defective ties for a given class or track per 39-foot segment (Track and Safety Standards).

15. 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

16. Superelevation Clearance
e=E*t/G Where, E=superelevation t= height of car G= Gauge distance So e+m is the additional clearance needed

17. Overhead Clearance
Telltales used to be used to warn trainmen on top of the train of an upcoming tunnel

18. 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

19. Questions?