Does anyone know how far Amtrak spaces their cantanary line supports apart? Like how far apart are the poles that hold up the lines?
The supports were erected by the PRR and N H in the 1930s. The distance between support poles was a function of curvature. As I recall the PRR standard on straight track was about 120'.
TrainsRock Does anyone know how far Amtrak spaces their cantanary line supports apart? Like how far apart are the poles that hold up the lines?
Depends on whether it is straight track or curves. Even new constant tension CAT New Haven - BOS has closer supports on curves than straight track. Unfortunately the PRR supports are too far apart for HSR constant tension CAT. AMTRAK's vision plan and its upgrade plans have noted that a support between each of the present PRR supports will be needed to increase speeds to 150 mph for the present variable tension CAT. To go above 150MPH on the NEC constant tension CAT will have to be installed. Cost over $1B NYP - WASH. AMTRAK notes that the additional suppports will come first then they will install constant tension CAT. ( variable tension gets its name from fact that temperature variations change the tension on the CAT).
Curve tracks have supports closer depending on how much curvature the track has both constant and variable.
I know for a fact that Amtrak does not need extra supports for constant-tension catenary on straight track. There is absolutely no reason why constant-tension catenary -on straight track- requires closer supporting bridges. All that is necessary is a third or fourth messanger wire between the two existing supports with the connection to the regular messanger (at the midpoint) via pulley instead of hard connection. The added messanger wire needs to be constant tension itself with pulley and weight at one or the other of the supports.
Sounds like Amtrak may need a European catenary engineer to straighten them out!
The old: "if you have a problem, thow money at it."
On MNCR the catenaries are about 270 feet apart on straight rail.
My recollection is that there are typically 20 per mile. If you want to know more precisely, you can scale them from Google maps.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
ndbprr The supports were erected by the PRR and N H in the 1930s. The distance between support poles was a function of curvature. As I recall the PRR standard on straight track was about 120'.
Are you sure about the 120' spacing? That seems pretty close for catenary on straight track. The pole spacing for simple suspension trolley wire on an interurban line was about 100'. The catenary construction should allow more than an additional 20 between supports.
daveklepper I know for a fact that Amtrak does not need extra supports for constant-tension catenary on straight track. There is absolutely no reason why constant-tension catenary -on straight track- requires closer supporting bridges. All that is necessary is a third or fourth messanger wire between the two existing supports with the connection to the regular messanger (at the midpoint) via pulley instead of hard connection. The added messanger wire needs to be constant tension itself with pulley and weight at one or the other of the supports. Sounds like Amtrak may need a European catenary engineer to straighten them out! The old: "if you have a problem, thow money at it."
I'm not a catenary engineer, but I have to agree with you. I can't think of any reason why constant tension would require a doubling of the support bridges. It doesn't make any sense. They wouldn't be carrying any additional weight or longitudinal stresses (if anything, they might be carrying less weight if the new catenary eliminates the secondary messenger, like the way the South Shore Line catenary is being reconstructed). The only change to the supporting bridges I can see that might be necessary would be on the structures holding the tension weights, since they would probably need to be strengthened and/or braced to bear the longitudinal stress of the catenary.
The Europeans like 100 meters for Cantenary support on straight track. Especially the Germans and Swiss. The Germans put distance markers every .2 of a kilometer and with Teutonic efficiency that is every other cantenary support on straight track.
A lot esier to beef up existing structures for the added tensioning weights than to build new structures. 100 foot spacing might be ideal, but if the Germans had an existing line with 120 foot spacing, they would keep that spacing and use half-way additional support with an additional messanger wire.
Rough scaling from Google Maps - spacing south of Princeton Jct = 280'
280? Well, I guess Amtrak does indeed need the additional structure. Apologies, Amtrak!
Fixed tension catenary pole spacing on the corridor is typically 265 foot apart.
The question of catenary support spacing on curves is one of geometry: the contact wire between supports follows the cord of the track curve radius where the offset would exceed the half-length of the pantograph contact surface, allowing for curve over- and under-balance and tolerances for track cross-elevation irregularities.
Hmm, the Germans use 100 meters (~325 feet) why would Amtrak need to shorten from 280 feet, heavier wiring?
I just posted a question on cost on the London to Cardiff electrification thread. They seem to be able to manage to do a double track mainline at ~$11 mil/mile, which seems a lot cheaper than numbers we've been seeing here.
C&NW, CA&E, MILW, CGW and IC fan
Constant tension (circa 1999) catenary pole spacing on the corridor(New Haven to Boston)approximately 185 foot apart.
NEC Constant Tension Cantenary on a curve (Branford CT). A view of the poles, track, and the super elevation of the track in the curve. Note the Constant Tension is pulling the left track trolley wire hard to the left while the right track trolley wire is nearly vertical.
Love the high tec tape on the Acela's wiper blades.
Don U. TCA 73-5735
NWKTrainer Constant tension (circa 1999) catenary pole spacing on the corridor(New Haven to Boston)approximately 185 foot apart.
A review of several CAT failures over the years may shed some light on the closer AMTRAK future spacing on the PRR side and the spacing on the NH - BOS segment. There have been several times CAT has collasped on the PRR variable tension CAT due to heavy snow and/or ice. As a witness to power lines coming down during previous ice storms I have been in that may be a reason? Ontario power had high tenson lines years ago that collasped under an ice storm.
A question is how often do the cited European RRs have these conditions?
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