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Ask Trains: How do railroads determine a grade on track charts?

By | August 15, 2019

Published Aug. 15, 2019

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Conrail C36-7 No. 6628 works an eastbound train in New York’s Southern Tier east of Lanesboro, Pa., near the Pennsylvania-New York border in 1985. This section of track has a grade, what percentage that shows up on a track chart is determined by how precise the charts are.
Michael S. Murray
Q: Some lengths of track appears undulating, especially for a mile or more. How is grade determined when all these ups and downs exist? — Michael Knight Hattiesburg, Miss.

A: Grade is measured with a simple geometric formula of rise over run. If the track climbs one foot in 100 feet, that’s a one percent grade. Two feet of rise in 100 feet is a two percent grade, and so on.

Railroad track charts show the track arrangement, curvature in degrees and minutes, and grade down to a hundredth of a percent. The interval over which grade changes are shown vary by the railroad and territory. On Norfolk Southern, these range from 0.1 mile on former Southern lines to 1 mile on former Conrail lines, a Norfolk Southern railroader tells Trains. The smaller the interval, the more precisely the track chart follows the actual track. Resolutions smaller than a few tenths of a mile are typically unnecessary given the size of typical trains.

In recent years, most railroads have added GPS-generated geographic information systems data, where the elevation intervals are on the order of feet. — Tyler Trahan

One thought on “Ask Trains: How do railroads determine a grade on track charts?

  1. Accompanying photo looks like BUOI climbing to Gulf Summit. Nice to see the Southern Tier(ex EL) get some notice!!

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