Back in the 1980s (?) TVA proposed to install electrification on both the SOU (NS) and the CSX lines between Cincinnatiti and ATL. TVA would even supply the electric motors that would be used by both SOU and CSX. RRs were requiring TN DOT to put several new and replacement bridges of the named routes and yards. Cannot remember exact height but 23 feet above top of rail comes to mind. That may have been due to electrifications then were only though to be 12.5 Kv or maybe 25 Kv. As well now 141 RE rail stand taller than what was installed then.
Believe TN DOT finally got that reduced but am not sure???
Common carrier freight railroads have a 24’-6" target height for catenary electrification. Less than that and you are insulating bridges (lotsa fun with reinforced concrete) and having adverse induction issues. 23’-0" is only protecting people (switchmen) on top of cars for the most part. Model Law from 1958 set the height originally at 22’-6" (railroads adding another 6" as “cushion” for surfacing)…Almost immediately, the states in the eastern 1/3 of the country started whittling that down because of their already older bad clearances and the fact that any major modification to the existing bridge or structure would require the target law height to be met (which would require major $$$ to accomplish and end the structure’s "grandfathered-in " status.
Outside of catenary, the heights for wirelines above the track is set by NESC based on potential/voltage of the wireline and won’t be less than 27’ above the track.
There are still too many rubber-tired engineers (structural, civil, electrical) that have not woken up to the fact that there are hard and fast rules to be followed. (See AREMA Ch 28 [Compilation of state laws) and C1, plus NESC)… It is not OK to guess and blunder around railroads and clearances, but they continue to do so. The telephone and fiber people are by far the most reckless/clueless of the bunch…
[soapbox]And as stated many times on this forum, State DOTs frequently are not qualified to railroad with not a single qualified railroader on staff. These yo-yo’s start playing with design criteria rules and it starts getting messy. Scary.[X-)][X-)][X-)]
How true. Live near ATT office. It has added so much copper and fiber to the travelers along the street that now all the cables are lower than the US 13 feet 6 inch clearances. Someone noted that to an ATT crew which crew ignored . Well a restaurant driveway had a TT delivery enter with a big snag. Fortunately no cable breaks. Took months to get a taller 7200 volt pole and to raise power lines, then TV cable, and finally the telephone lines. Have a concrete truck coming this fall and will have to check to see if it will clear the possible snag in front of house.
Our local electric company has placed all wire crossing CSX with guy wires on the poles that cross CSX so the poles will not lean toward the the tracks causing the power lines to sag toward tracks.
Streak: Anything less than 15.5 feet is a bozo-no-no at any place … and you still have to figure sag and voltage into that minimum number (which can only go up)…Driveways that regulary see commercial trucks will push that figure to 16’
…and nobody wants to pay to raise a pole line, especially the people that built the original pole line before all the other spaghetti was added on. (In Colorado, we’ve seen some major fails with crossings and parallel lines (impedance) in recent history. Service and income requirements should NOT be making safety be an afterthought …the same also has requirements for clearing the lines above the bottom wires.