Back in the steam-era here along the Norfolk and Western they would run weed-spray trains and try to keep the ROW as clear as possible. In South Africa when were there in the 70's and 80's it was quite dry, and generally the ROW was burned on both sides of the tracks in many places. I don't know if that was a preventative burn, or scorched from the steam engines. I never heard about anything being a problem with steam running there though, with regard to trackside fires.
Greg
PS. Check out this shot made in 1977. This is a long-distance passenger train doing about 60 mph on the De Aar to Kimberly line. This line saw about 50-60 steam trains a day, and look at the dry tender on the side of the tracks. No blacken areas except a few rocks. Its a dry area.
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