p-REES 1: Module 1-E Railway Alignment Design and Geometry AREMA/FRA Basis Photos © Michael Loehr 2015

AREMA Mission : The development and advancement of both technical and practical knowledge and recommended practices pertaining to the design, construction and maintenance of railway infrastructure. Photo © Michael Loehr 2015

Federal Railroad Administration (FRA) The Federal Railroad Administration (FRA) was created by the Department of Transportation Act of 1966. Mission: The Federal Railroad Administration’s mission is to enable the safe, reliable, and efficient movement of people and goods for a strong America, now and in the future. Purview: ‘…“general railroad system of transportation” (general system), which is defined as “the network of standard gage track over which goods may be transported throughout the nation.” (49 CFR Part 209, Appendix A)…’

Federal Railroad Administration (FRA) Safety: FRA's Office of Railroad Safety promotes and regulates safety throughout the Nation's railroad industry. Hazardous Materials   Motive Power and Equipment Operating Practices Signal and Train Control Track Photo © Michael Loehr 2015

Tangent Element Length Length of any track element Minimum – Based on Alignment, Equipment, Operating Speed, and Truck Centers Allowable - 100 feet is a common value Preferred - 3 times the velocity in mph. Example Track speed 60 mph, preferred length = 3 X 60 = 180’ Note: Individual railroads and Agencies will have values specific to their system Photo © Michael Loehr 2015

Curvature Railroad Practice Dc = Angle sub-tended by a 100’ Chord Why ( ) Railroad Practice Chord Definition for Curves Specified by Degree and expressed as Dc Dc = Angle sub-tended by a 100’ Chord Why Stakeout without tables Direct Measurement by String Lining without survey Figure © Michael Loehr 2015

Curvature Radius vs Dc cheat sheets Maximum curvature Design to even Dc not r Maximum curvature Freight and Passenger Yards Dc = 12d 30’ (r = 459.28’) Coal Loading Loops Dc = 10d 00’ (r = 537.69’) New Mainline Dc = 1d 00’ (r = 5729.65’) Note: 2° 30’ = 2d 30’ this format allows asci file transmittal Figure © Michael Loehr 2015

Spirals Spirals provide smooth transition from tangents to curves Sometimes used in Highway Design, but not common practice Straight Entering Curve Full Curve Figure © Michael Loehr 2015

Spirals Functions Application Reduce lateral and jerk forces Spirals provide area to runoff superelevation Application All curves in Main Tracks Infrequently used in Yards Photo © Michael Loehr 2015

Spirals AREMA CADD Xo ≅ Ls / 2 Yo ≅ O / 2 10 Chord Clothoid Ls Yo Xo Figure © Michael Loehr 2015

Spirals Nomenclature D = degree of circular curve d = degree of curvature of the spiral at any point l = Length from the T.S. or S.T., to any point on the spiral having coordinates x and y s = length l in 100-foot stations L = total length of spiral S = length L in 100-foot stations d = central angle of the spiral from the T.S. or S.T. to any point on the spiral D = central angle of the whole spiral a = deflection angle from the tangent at the T.S. or S.T. to any point on the spiral b = orientation angle from the tangent at any point on the spiral to the T.S. or S.T. k = increase in degree of curvature per 100-foot station along the spiral All functions are in feet or degrees unless otherwise noted Figure © AREMA 2015

Spirals Figure © AREMA 2015

Superelevation Picture Centpacrr at en.wikipedia

Superelevation Figure © AREMA 2015

Superelevation Measured and described in Inches Nomenclature Eq = Equilibrium Elevation Ea = Elevation Actual Eu = Elevation Underbalance Relationships Eq = Ea + Eu For Standard Gage Track and Equipment Eq = 0.0007 V2 Dc Photo © Wikipedia® 2015

Superelevation Figure © Michael Loehr 2015

Superelevation Ea Max Underbalance Freight uses up to 6” depending on the Railroad Passenger uses up to 8” Underbalance Freight uses 1½” to 2½” Commuter uses 3” to 4” Intercity uses 3” to 4” Photo © Michael Loehr 2015

Superelevation Why is Underbalance used? Not all trains operate at the same speed To balance rail wear between both rails To reduce truck hunting by having a net outward force Reduce plate cutting on wooden ties Photo © Wikipedia® 2015

Superelevation Ea 3 ¼” 63 2° 15’ = 2d 15’ Figure © Michael Loehr 2015

Superelevation Figure © Michael Loehr 2015

Grades Photo © Michael Loehr 2015

Grades Forces from Grades G = rise / run Fg = G * W 1.5% grade, 134 Ton Locomotive Fg = 0.015 * 134 = 2.0 tons Fg rise run W Figure © Michael Loehr 2015

Grades Maximum Grades Steeper grades can be surmounted if they are short Ice and Leaf oil can limit operations on grades Freight 0.5% Desirable Maximum 1.5% Typical Passenger Matches freight limits typically Can be 2% to 3% with no freight Figure © AAR 2015

Grades Curve Compensation Application Curves cause additional drag on the train due to flange friction Flange forces are increased due to chording of the cars due to tension in the train Application Add 0.04% grade for each degree of curve 1% compensated grade desired with 4 degree curve Actual design grade = 1.0% – (0.04% * 4) = 0.84% Existing 0.5% grade with a 6 degree curve Compensated grade = 0.5% + (0.04% * 6) = 0.74%

Vertical Curves The lengths of parabolic vertical curves on Freight, Commuter, and Inter-City Passenger railroads are determined according to AREMA requirements. Basic Formula L = D * V2 * 2.15/A L = length of vertical curve in feet V = speed of train in mph A = vertical acceleration in feet/sec2 D = absolute value of the difference in rates of grades (as a decimal) 2.15 = a conversion factor Freight Design Acceleration - A = 0.10 Passenger Design Acceleration - A = 0.60

Vertical Curve A parabola is used for the vertical curve in which the correction from the straight grade for the first station is one half the rate of change, and the others vary as the square of the distance from the point of tangency. Where points fall on full stations, it will be necessary to figure these for only one half the vertical curve, as they are the same for corresponding points each side of the vertex. Corrections are (-) when the vertical curve is concave downwards (summit), and (+) when the vertical curve is concave upwards (sag). The rate of change per station is calculated as follows: R = D/L Where: R = Rate of change per station D = Algebraic difference of the two intercepting grades L = Length of vertical curve in 100-ft. stations M = Correction from the straight grade to the vertical curve Figure © BNSF 2015

Vertical Curves Design Example - Length L = D * V2 * 2.15/A Crest Vertical Curve Grade 1 = 1%, Grade 2 = - 0.5% Freight Design @ 50 mph L = (0.01 – (-0.005)) * (50 * 50) * 2.15/0.10 = 806.25’ Passenger Design @ 70 mph L = (0.01 – (-0.005)) * (70 * 70) * 2.15/0.60 = 263.38’ L = 806.25’, say 825’

Vertical Curves Design Example - Elevations Assume length = 600 feet (6 stations) D – 0.50 minus – 0.22 = 0.72 R = 0.72/6 = 0.12 Figure © BNSF 2015

Clearances Railroad Clearances are Statutory by State Figure © AREMA 2015

Clearances Railroad Clearances also vary by Railroad Figure © BNSF/UPRR 2015

Michael Loehr Practice Leader Rail & Transit – Americas - Civil Transportation Business Group CH2M HILL 8720 Stony Point Parkway, Suite 110 Richmond, VA 23235 Mobile 570.575.4692 Michael.Loehr@ch2m.com