Roadbed width at the cable trough, Otter Subdivision MP 148.20 to 151.10

The shoulder break in the mobile LiDAR ground surface was compared with the standard plan’s clearance behind the signal cable trough at every 10-ft station. The roadbed is too narrow over 2,270 ft in 7 locations. A first screening that used the wrong criterion was withdrawn and is kept here for comparison.

Cable trough layout, sheets CT-101 to CT-112Mobile LiDAR, Oct 14, 2026Main track alignment, LandXMLStd. Plan RB-101, Sheet 2Trough on left side facing increasing MPNAD83(2011) Kansas South (FIPS 1502), US survey ft · NAVD 88Sta. 100+00 to 253+00Prepared Nov 5, 2026

Summary

Fill widening

2,270 ft of roadbed is too narrow, in 7 locations

The shoulder break is less than 1'-6" from the outside face of the trough, or less than 2'-0" on the high side of the 2°15′ curve. The largest deficits are 0.87 ft at Signal 1486 and 0.76 ft along Block 14, Sta. 203+90 to 208+10. Theoretical fill to the required line is about 410 CY (Std. Plan RB‑101, Sheet 2).

Next step: design fill widening for all seven locations. Along Block 14 the right-of-way line is 3.5 ft beyond the toe of slope.

Screening 1 withdrawn

12.00 ft from centerline was the wrong criterion

The first screening used the new-construction dimension from Sheet 1 of the standard plan and flagged 6,080 ft. Sheet 2 covers existing roadbed with a cable trough and measures from the outside face of the trough. Of the flagged length, 4,230 ft meets that requirement.

Do not use the Screening 1 list for design or quantities.

Signal locations

2 locations at signals were missing from Screening 1

At Signals 1486 and 1496 the trough runs behind the signal foundations, 10.50 ft from centerline per layout sheets CT‑102 and CT‑106. That puts the required shoulder at 13.20 ft, but the shoulder break is at 12.28 to 12.69 ft. 420 ft in total.

Next step: include both locations in the widening or reroute the trough around the foundations.

Roadbed width station by station

The profile shows the shoulder break from the LiDAR surface against the required line, which is the outside face of the trough plus the minimum clearance. Click the overview to move the window and click the profile to see the cross section. Switch to Screening 1 or Compare to see what the withdrawn screening flagged.

Criterion
Curve allowance
0Roadbed too narrow
0Locations
0Largest deficit
0Theoretical fill
0Screening 1

Each station covers 10 ft. The shoulder break is the grade break between roadbed and fill slope in the ground-classified point cloud, measured perpendicular to the track alignment.

Cross section

Locations to widen

LocationLengthLargest deficitFill

Why Screening 1 was withdrawn

Screening 1 took the requirement from the wrong sheet of the standard plan. That dimension applies to new construction and does not account for where the trough is. The bar shows how the flagged length splits between the two criteria.

Screening 1, withdrawn

Std_Plan_RB-101_Roadbed_Cable_Trough.pdf, Sheet 1 “Standard Roadbed Section, New Construction,” Note 3

“Track centerline to shoulder break: 12'-0" minimum.”

Applies to new roadbed. Flagged 6,080 ft in 12 locations, of which 4,230 ft meets the clearance behind the trough.

Current criterion

Std_Plan_RB-101_Roadbed_Cable_Trough.pdf, Sheet 2 “Existing Roadbed with Cable Trough,” Notes 2 and 3

“Clear distance from outside face of cable trough to shoulder break: 1'-6" minimum. On the high side of curves 2°00′ and sharper, increase to 2'-0".”

Trough offsets are taken from the layout sheets. Gives 2,270 ft in 7 locations, including 420 ft at Signals 1486 and 1496 that Screening 1 did not catch.

Sources and method

Sources

  • Otter_Sub_Cable_Trough_Layout_MP148-151.pdfCable trough layout plan, 1" = 50'. Trough offsets, offsets around signal foundations and right-of-way lines12 sheets
  • Otter_Sub_MP148-151_Mobile_LiDAR_Ground.lasGround-classified point cloud from mobile LiDAR, Oct 14, 2026. NAD83(2011) Kansas South, US survey ft, NAVD 88approx. 4 pts/sq ft
  • Otter_Sub_Main_Track_Alignment.xmlLandXML horizontal and vertical alignment of the main track, three curves1 alignment
  • Std_Plan_RB-101_Roadbed_Cable_Trough.pdfStandard roadbed section. Sheet 1 new construction, Sheet 2 existing roadbed with cable trough2 sheets

Method

  1. The main track alignment was read from the LandXML file and divided into 10-ft stations from Sta. 100+00 (MP 148.20) to Sta. 253+00 (MP 151.10), 1,531 stations in total.
  2. At each station a cross section perpendicular to the alignment was cut on the trough side. The shoulder break was taken as the grade break between roadbed and fill slope in the point cloud, and the fill height as the elevation difference between shoulder break and toe of slope.
  3. The inside face of the trough was read from the layout sheets: 8.20 ft from centerline typically and 10.50 ft at Signals 1486, 1496 and 1505. The trough’s outside width of 1.20 ft was added.
  4. The required line is the outside face of the trough plus the clearance from Sheet 2 of the standard plan, with the allowance on the high side of curves 2°00′ and sharper.
  5. Stations where the shoulder break falls inside the required line were grouped into locations. Theoretical fill is the deficit times the fill height per foot of track, with the 1.5H:1V slope shifted parallel, converted to cubic yards.
  6. Screening 1, with 12.00 ft from centerline, is shown for comparison. It was withdrawn when Sheet 2 showed that the requirement is measured from the outside face of the trough.

Assumptions and limitations

  • Bridge 149.27 over Otter Creek and the K-340 grade crossing are excluded. There is no fill there.
  • The LiDAR shoulder break is accurate to about ±0.15 ft. Locations with small deficits should be field-verified before the widening is designed.
  • Theoretical fill is computed to the required line. Widening is built with a minimum working width and benched into the existing slope, so actual fill quantities will be higher.
  • Slope stability, drainage and subgrade bearing of the widened fill are not evaluated here. AREMA Manual for Railway Engineering, Chapter 1 (Roadway and Ballast), and the railroad’s geotechnical requirements apply to the design.
  • Along Block 14 of the Original Town of Otter Creek the right-of-way line is 3.5 ft beyond the existing toe of slope per layout sheet CT-109. Room for widening needs to be confirmed.
  • The terms shoulder break, clearance and high side are used as on Std. Plan RB-101. The railroad’s engineering department should confirm that they match its own definitions, since the required line depends on them.