An Evaluation of the Geometric

Designs of Grade Crossings

Roxxie Mann

Highway-Rail Grade Crossing

• Highway-Rail Grade Crossings (HRGC) are locations where a transport axes crosses one or multiple railroad tracks at the same elevation (FHWA, 2014).

Types of HRGC• At-grade crossings

• Other crossings

Horizontal Alignment• To enhance the driver’s view of the crossing the

following are desired: o Right Angle Intersection of highway and trackso No nearby intersections or driveways

• Crossing should not be located on either highway or railroad curves.o Roadway curvature will compel drivers to concentrate on

the curve of the road rather than the oncoming train.o Railroad curvature will obstruct the sight distance of

oncoming traffic.

Vertical Alignment

Problems associated with HRGC

• Uneven Crossing Elevations

• Skewed Crossing

Project Objective• Individual

o To evaluate the geometric profiles of each site, as well as establish the required sight distance, braking distance and stopping distance while taking into account the adjustment factor due to the approach grade to the intersection and effect of skew

o To learn and understand MircroStation/Geopak to a level at which detailed geometric profiles of HRGC can be developed.

o To state the difference between obtaining coordinates from Lidar data, Google Earth, and Original Design

• Overallo Export coordinates into CarSim in order to simulate different

“real-life” scenarios and further analyze results from a civil engineers perspective.

Over View

84th Street in Lancaster County

• Located on 84th St. just off of Highway 2.

• Concern is sight distance • Omaha Public Power District Crossing

o Average of 1 Train/dayo Max. speed of 25 mph

• Posted Speed limit is 50 mph• Imagery Date 5/2012

Highway 92 in Butler County

• Located southwest of David City, Nebraska

• Issue is rough crossing• BSNF crossing

o 1 Train/dayo Max speed of 25 mph

• Posted Speed Limit 60 mph• Imagery Date 3/2014

King Road in Otoe County

• Located southwest of Nebraska City

• Two lane street with a low volume of traffic

• Concern is sight distance• Union Pacific Railroad Crossing

o 15 Trains/dayo Max Speed of 50 mph

• Posted Speed Limit is 50 mph• Imagery date 9/21/2012

Hwy N-79 in Lancaster County

• Located south of Agnew road on Hwy N-79

• Two lane street • Skewed crossing • Issue is sight distance• Union Pacific Railroad

Crossingo Average of 2 Trains/dayo Max. Speed of 40 mph

• Posted Speed Limit is 60 mph

• Imagery Date 5/2013

HWY 4 in Thayer County

• Located east of Davenport

• Two lane street runs over two parallel train tracks.o Roughly 12 ft apart

• Issue is rough crossing • Union Pacific Railroad

Crossingo 49 Trains/dayo Max. Speed of 70 mph

• Posted speed limit is 60mph

• Imagery Date 9/2008

Regarding Sight Distance

𝐷𝑇=𝐴𝑉 𝑇 [𝑉 𝐺

𝑎1+𝐿+2𝐷+𝑊 −𝑑𝑎

𝑉 𝐺+ 𝐽 ]

Case A Case B

Train speed (mph)

Case B Case ADeparture from stop Moving vehicle in (mph)

0 10 15 20 25 30 35 40 45 50 55 60 65 70 75 805 127 77 62 55 52 51 51 51 52 53 55 56 58 60 62 6410 255 155 123 110 104 102 101 102 104 106 109 112 116 119 123 12715 382  232 185 165 156 153 152 153 156 160 164 169 174 179 185 19120 509  310 247 220 208 203 203 205 208 213 219 225 232 239 246 25425 637  387 309 275 260 254 253 256 260 266 273 281 290 299 308 31830 764  465 370 331 312 305 304 307 312 319 328 337 347 358 370 38135 891  542 432 386 365 356 355 358 364 373 382 393 405 418 431 44540 1019 619 494 441 417 407 405 409 416 426 437 450 463 478 493 50845 1146 697 556 496 469 458 456 460 468 479 492 506 521 537 554 57250 1273 774 617 551 521 509 507 511 520 532 546 562 579 597 616 63555 1401 852 679 606 573 559 557 562 572 585 601 618 637 657 678 69960 1528 929 741 661 625 610 608 614 624 639 656 675 695 717 739 76365 1655 1007 803 716 677 661 659 665 676 692 710 731 753 776 801 82670 1783  1084 864 771 729 712 709 716 728 745 765 787 811 836 862 89075 1910 1161 926 826 781 763 760 767 780 798 820 843 869 896 924 95380 2037  1239 988 882 833 814 811 818 832 852 874 899 927 956 986 101785 2164 1316 1050 937 885 865 861 869 884 905 929 956 985 1015 1047 108090 2292 1394 1111 992 937 915 912 920 936 958 983 1012 1042 1075 1109 1144

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 900

200

400

600

800

1000

1200

1400

Case A:Moving Vehicle (mph)

10 mph 15 mph 20 mph 25 mph 30 mph 35 mph 40 mph45 mph 50 mph 55 mph 60 mph 65 mph 70 mph 75 mph

Train Speed (mph)

Sigh

t Dist

ance

Req

uire

d (ft

)

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 900

500

1000

1500

2000

2500

120240

361481

601721

842962

10821202

13221443

15631683

18031924

20442164

Case B:Departure from stop

Train Speed (mph)

Sigh

t Dist

ance

Req

uire

(ft)

0 10 20 30 40 50 60 70 80 90 1000.00

2.00

4.00

6.00

8.00

10.00

12.00

Sight Distance Leg along the Highway

Train Speed (mph)

Dist

ance

alo

ng H

ighw

ay fr

om cr

ossin

g (ft

.)

Regarding Skewed Crossing• Case A-Intersections with no control• Case B-Intersections with stop

control on the minor road o Case B1-Left turn from the minor roado Case B2-Right turn from the minor roado Case B3-Crossing maneuver from the

minor road• Case C-Intersections with yield

control on the minor roado Case C1-Crossing Maneuver from the

minor roado Case C2-Left or right turn from the

minor road• Case D-Intersections with traffic

signal control• Case E-Intersections with all-way

stop control• Case F-Left turns from the major

roads

The recommended dimensions of the sight triangles vary with the type of traffic control used at the intersection.

IntersectionControl

Adjustment Factor for Sight Distance Based on Approach Grade

HWY 4 –LHWY 92- L & RHWY 79- L & R84th- L & RHWY 4 - R

King Rd - L

King Rd-R

Case A-Intersections with no traffic controls

Design Speed (mph)

Length of Leg (ft)HWY 4 HWY 92 HWY 79 84th St. King Rd.

-3% +4% 0% 0% .5% -.5% -2.5% +1% -4% -6%15 70 70 70 70 70 70 70 70 70 70 7720 90 90 90 90 90 90 90 90 90 90 9925 115 115 115 115 115 115 115 115 115 115 126.530 140 140 140 140 140 140 140 140 140 140 15435 165 165 148.5 165 165 165 165 165 165 181.5 181.540 195 195 175.5 195 195 195 195 195 195 214.5 214.545 220 220 198 220 220 220 220 220 220 242 24250 245 245 220.5 245 245 245 245 245 245 269.5 29455 285 285 256.5 285 285 285 285 285 285 313.5 34260 325 325 292.5 325 325 325 325 325 325 357.5 39065 365 365 328.5 365 365 365 365 365 365 401.5 43870 405 405 364.5 405 405 405 405 405 405 445.5 48675 445 445 400.5 445 445 445 445 445 445 489.5 53480 485 485 436.5 485 485 485 485 485 485 533.5 582

10 20 30 40 50 60 70 80 900

100

200

300

400

500

600

700

Modified Sight Distance with Adjustment Factor on Approach Grade-6% -4% -3% to 3% 4%

Design Speed (mph)

Leng

th o

f leg

(ft.)

Modified stopping sight distance

Modified Stopping Sight Distance

Design Speed (mph)

Brake Reaction

Distance (ft)

Braking Distance

on Level (ft)

Stopping Sight Distance Downgrades Upgrades

Calculated (ft)

Design (ft) 3% 6% 9% 3% 4% 6% 9%

15 55.13 21.60 76.72 80 78.7 81.2 84.2 74.9 74.5 73.5 72.320 73.50 38.39 111.89 115 115.5 119.8 125.2 108.8 107.9 106.2 103.925 91.88 59.99 151.86 155 157.4 164.3 172.7 147 145.6 142.9 139.530 110.25 86.38 196.63 200 204.6 214.5 226.6 189.7 187.6 183.8 178.835 128.63 117.58 246.20 250 257.1 270.5 287 236.7 233.9 228.8 221.940 147.00 153.57 300.57 305 314.8 332.3 353.9 288.2 284.5 277.8 268.845 165.38 194.36 359.74 360 377.8 399.9 427.2 344 339.4 330.9 319.650 183.75 239.96 423.71 425 445.9 473.3 506.9 404.3 398.6 388.1 374.255 202.13 290.35 492.47 495 519.4 552.5 593.2 469 462.1 449.4 432.460 220.50 345.54 566.04 570 598.1 637.4 685.9 538.1 529.9 514.7 494.665 238.88 405.52 644.40 645 682 728.2 785.1 611.6 602 584.2 560.570 257.25 470.31 727.56 730 771.2 824.7 890.7 689.6 678.4 657.8 630.3

75 275.63 539.90 815.52 820 865.6 927.1 1002.9 771.9 759.1 735.4 703.9

80 294.00 614.29 908.29 910 965.2 1035.21121.4 858.6 844.1 817.1 781.3

𝑑𝑟=1.47𝑉𝑡 𝑑𝑏=1.075𝑉 2

𝑎𝑑𝑏=

𝑉 2

30( 𝑎32.2

±𝐺)

10 20 30 40 50 60 70 80 900.00

200.00

400.00

600.00

800.00

1000.00

1200.00

Brake Reaction DistanceBraking Distance on LevelStopping Sight Distance-3%-6%-9%3%4%6%9%

Design Speed (mph)

Dist

ance

(ft.)

Effects of Skew

𝑡 90=√ 2𝑊 1

𝑎𝑡 𝑠𝑘𝑒𝑤=√ 2𝑊 2

𝑎

𝑡 90=2.74 𝑠

Angle Street

width (ft) (ft.)time of skew

Change in time

84th St 80 17 17.10 2.75 0.01

HWY 79 32 17 30.83 3.69 0.95

HWY 92 38 17 57.36 5.03 2.29

King Rd 80 17 17.10 2.75 0.01

HWY 4 120 17 29.28 3.60 0.86

Case B-Intersections with Stop Control on the Minor Road:

Crossing Maneuver from the Minor Road

𝐼𝑆𝐷=1.47𝑉 𝑡𝑔 = time gap at design speed Passenger car 6.5 s plus the effect in skew value

Design Speed (mph)

Stopping Sight

Distance (ft)

Intersection sight distance for passanger cars with skewed and approaching grade factors

HWY 4 (skewed) HWY 92 (skewed) HWY 79 (skewed)84th St

(skewed)King Rd

(skewed)

L -3% R 4% L 0 % R 0% L .5% R .5% L 2.5 %R -

2.5% L -4% R- 6%

15 80 162.29 162.29 193.82 193.82 164.27 164.27 143.55 143.55 143.55 157.90

20 115 216.38 216.38 258.43 258.43 219.03 219.03 191.39 191.39 191.39 210.53

25 155 270.48 270.48 323.03 323.03 273.79 273.79 239.24 239.24 239.24 263.1730 200 324.58 324.58 387.64 387.64 328.55 328.55 287.09 287.09 315.80 315.80

35 250 378.67 340.80 452.25 452.25 383.30 383.30 334.94 334.94 368.43 368.43

40 305 432.77 389.49 516.85 516.85 438.06 438.06 382.79 382.79 421.07 421.07

45 360 486.86 438.18 581.46 581.46 492.82 492.82 430.64 430.64 473.70 473.7050 425 540.96 486.86 646.07 646.07 547.58 547.58 478.49 478.49 526.33 574.18

55 495 595.06 535.55 710.67 710.67 602.33 602.33 526.33 526.33 578.97 631.60

60 570 649.15 584.24 775.28 775.28 657.09 657.09 574.18 574.18 631.60 689.02

65 645 703.25 632.92 839.88 839.88 711.85 711.85 622.03 622.03 684.23 746.4470 730 757.34 681.61 904.49 904.49 766.61 766.61 669.88 669.88 736.87 803.85

75 820 811.44 730.30 969.10 969.10 821.36 821.36 717.73 717.73 789.50 861.27

80 910 865.54 778.98 1033.70 1033.70 876.12 876.12 765.58 765.58 842.13 918.6910 20 30 40 50 60 70 80 90

0

200

400

600

800

1000

1200

Intersection Sight Distance for Passanger Cars with Skewed and Approach Grade Factors

Stopping Sight DistanceHWY 4 Left/West Approach-3%HWY 4 Right/East Approach 4%HWY 92 Left/West Approach 0%HWY 92 Right/East Approach 0%HWY 79 Left/West Approach .5%HWY 79 Right/East Approach .5%84th St Left/West Approach 2.5%84th Right/East Appraoch -2.5%King Rd Left/West Approach -4%King Rd Right/East Approach -6%

Design Speed (mph)

Stop

ping

SIg

ht D

istan

ce (f

t)

Part 2• Which way would be the best to obtain a test site

coordinates (horizontal, vertical and elevation) and create a 3D model?o LIDARo Google Earth o Original Design

HWY 4 Visit

Difference over time

Google Earth Image from 2009

Site picture 2014

LIDAR Data

Google Earth

HWY 4 HRGC 1962

RR

RR Xing @ 184+00.75TT=1613.46 ft @ Sta. 184+00.75 Centerline of Hwy 4

Existing

Original Design

Conclusions• Regarding Part one

o For each test site, intersections with no traffic signals and traffic signals on minor road (roadway) • sight distance• stopping distance • braking distance• consideration of different approaching grade (from left and right)• the effect of the skew

• Regarding Part twoo Google Earth

• The most efficient way to retrieve coordinates and build 3D models o Original Design Plans

• Gave a more realistic and the exact elevation, resulting in a more precise evaluation when discovering the vehicle’s dynamic profile after exported into CarSim

References• Federal Highway Administration Safety Program (FHWA). (2013).

"Railway-Highways Crossing (Section 130) Program." U.S. Dept. of Transportation, Washington D.C.

• Federal Railroad Administration (FRA). (2010). "Highway-Rail Grade Crossings Handbook." U.S. Dept. of Transportation, Washington D.C.

• Gillespie, Thomas D. (2004). "CarSim Data Manual." Mechanical Simulation Corporations, Michigan.

• Montana Department of Transportation (MDOT). (2012). “Introduction to GeoPak MDT Road Design V8i SS2.” Civil Engineering Infrastructure Design & Road Design Software. Montana Department of Transportation, Montana.

• Ogden, Brent D. Railroad-highway Grade Crossing Handbook. Washington, DC: U.S. Dept. of Transportation, Federal Highway Administration, 2007. Print.

• Tennessee Department of Transportation (TDOT). (2009). "MicroStation V8." 3D CAD Design & Modeling Software. Tennessee Dept. of Transportation, Tennessee.