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

SwitchClosure CurveFrog

• Are designated by their frog numberhttp://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 secondTurnout immediately after the first Arema p. 252

• Multiple turnouts in a series are called a ladder

http://www.building-your-model-railroad.com/images/railyard1.jpg

•Maximum Ladder Angle

∂=Sin-1(S/L)∂: Deflection angleS: Yard track spacingL: Length of turnout

Design of Yards

• Storage Yard• Local Yards• Flat Switching Classification Yards

http://www.airphotona.com/stockimg/images/00200.jpg

Pueblo, Colorado

http://z.about.com/d/goeurope/1/0/a/Y/torino-railroad.jpg

Torino, Italy

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

http://jeffwilk.com/granduncle.php?big=13

http://transit.toronto.on.ca/gotransit/2304.shtml

Recruiter

Willowbrook Yard, Toronto

Other Design Considerations

http://www.flickr.com/photos/grundlepuck/151676388/

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

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

http://www.panoramio.com/photo/6355575

Clearance• Side clearance ismeasured from thecenter 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 centerlineS=m + w/2 Where,

m=R-(2*R-(t/2)*2)1/2

R=Radius of track curvet= truck centersw=railcar width Arema p. 259

Superelevation Clearance

e=E*t/G Where,

E=superelevationt= height of carG= Gauge distance

So e+m is the additional clearance needed

http://zierke.com/shasta_route/picpages/rb22994.html

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?