Re: Trolly Tracks
Date: May 19, 2015 12:14AM
> So you're telling us that the current returns from
> the el via streetcar tracks? I totally don't buy
> that at all. As I understand electric traction the
> third rail or overhead wire provide one path and
> the tracks in use the other. I don't understand
> why they would ever have been linked in the first
> place*, let alone currently still linked.
> *Especially since they were built by different
> companies and you'd have current feeding down the
> el structures to street level. And somehow, that
> would have shorted out the streetcars.
Yeah, I know it sounds crazy, but that's what I thought when I started working for the City of Chicago as a traffic engineer in 1983. I think it's mostly from the formation of the CTA, and since they acquired CSL substations, they were able to use them to increase traction power available to the L. But the City has, or had, a "Corrosion Prevention Task Force" under what was several City agencies (including what was then Public Works, who I worked for) and the CTA, to deal with this, either maintaining the old tracks as a current return, or replacing them with cables. That's my story, and I'm stickin' to it!
I do remember one of my supervisors took a contractor to task, who had cut one rail clear through with a power saw, and was starting on the second. The supervisor said he knew that track was still live, and there would have been a nasty 600-volt arc if the contractor had finished that cut.
Another consideration is that those tracks are deep to reduce deflection as streetcars moved over them, so the cost of digging them up would be prohibitive.
There's also many places where the cable car conduits are still extant under the tracks, so they would have to be dug up too. We had a heck of a time when we modernized the traffic signals at Ogden and Madison, because we had to dig under the tracks [u]and[/u] the cable conduits. Those tracks were still live current returns, as well.
Edited 1 time(s). Last edit at 05/19/2015 12:32AM by Jeff_Weiner.