PAR Heat Restrictions NH/ME (Downeaster)

In the Amtrak Success Stories thread there was recent discussion of the effect of PAR heat restrictions imposed on the NH/ME route that affected Downeaster service. Do all railroads impose heat related speed restrictions in the same fashion as PAR? Is there techonology available that would allow them to detect heat related problems with the track before they occur, as opposed to only relying on ambient temperatures?

The old way, of course, was to use jointed rail and oil the fishplates so it would never get into significant compression or tension. But it cost a lot. Welded rail in rock ballast will *usually* stay put through a wide range of temperatures if it's installed properly. Strain gauges could be installed too. Both gauges and care in installation cost money that US RRs don't want to spend. I gather the UK has heat-related speed restrictions too. I have not heard of these on European high-speed rail; perhaps their tracks were built with sliding expansion joints as necessary.

I knew rails kinked in extreme heat due to expansion, but I did not realize that it was an issue as far north as Maine. Is there a corresponding cold threshold as well due to rail contraction?

A lot of it has to due with difference in temp from when the rail is installed vs the maximum temp it hits. You need to install at a nice mid-point in the expansion coeficient so that in the winter the rail doesn't shrink so much you end up with broken joint bars. Maine/NH (on the downeaster route) sees temps range from about -15 average annual minimum temp to about a few days close to 100 each year. The rail itself will often heat to much more than 100.

I had -- past tense, unfortunately -- an early '80s Conrail CWR installation manual. If ambient temperature was below a certain and now-forgotten level, dedicated propane burners were to be used to bring the rail up to a given temperature measured on the top of the rail before tight-spiking and anchoring. I don't recall any mention of Pandrol clips. The goal was to provide for expansion and contraction through a range of temperature extremes that would minimize kinks or pull-aparts. As far as I can remember, the manual had only one minimum ambient temperature instead of taking something like a USDA plant hardiness zone approach.

When PAR puts on the heat restriction, it also cuts maximum
speed on freight jobs from 40 to 25. I believe these heat
restrictions are a result of an Amtrak derailment on CSX at
Kensington MD in 2002. There were no fatalities, but many
injuries. Below are some details on the accident.
http://www.hoeyfarina.com/railroadhfamtrakheat.

I can't help but wonder what happens on other railroads. I've never heard of these kinds of restrictions affecting operations in places like North Carolina and Florida where temperatures are consistently warmer than Maine. Of course it's not as if these restrictions would make the national news either so to a certain extent I'm not surprised.

So is the present understanding that these types of restrictions are common throughout the South on and off all summer long?

I think part of the issue is that places like NC and FL don't have quite the same temperature extremes that we have up here, and also that the rails in those areas are heated to a higher temperature when they are initially laid, in order to take into account the average operating temperature when the rails are in service. If we heated our rails to the same temperatures that the NC and FL track crews used during the tracklaying process, then we'd get into trouble in the wintertime.

(All of the above is how it was explained to me by railroaders. Corrections welcome if I got it wrong in translation.)

Better to be safe than sorry, I suppose. Several years ago (early 2000s) there was a derailment on the St. Lawrence & Atlantic due to a heat kink on a hot day. Would the engineer have been able to stop short of the kink if a speed restriction had been in place? We'll never know for sure, but it's possible. Likewise, a passenger train has a better chance of being able to stop short of a kink at 40 than it does at 60-79.

When the SLR ran during the day they would frequently in the summer issue slow orders due to "extreme heat". Usually CWR went down to 25MPH

MEC407 wrote:I think part of the issue is that places like NC and FL don't have quite the same temperature extremes that we have up here, and also that the rails in those areas are heated to a higher temperature when they are initially laid, in order to take into account the average operating temperature when the rails are in service. If we heated our rails to the same temperatures that the NC and FL track crews used during the tracklaying process, then we'd get into trouble in the wintertime.

(All of the above is how it was explained to me by railroaders. Corrections welcome if I got it wrong in translation.)

Better to be safe than sorry, I suppose. Several years ago (early 2000s) there was a derailment on the St. Lawrence & Atlantic due to a heat kink on a hot day. Would the engineer have been able to stop short of the kink if a speed restriction had been in place? We'll never know for sure, but it's possible. Likewise, a passenger train has a better chance of being able to stop short of a kink at 40 than it does at 60-79.

MEC407,

Thanks for the explanation. Safety must always come first and it makes a great deal of sense that our climate extremes would cause these problems. Maybe at some point in the future NNEPRA will arrange for funding to PAR to install strain gauges etc. At least then the railroad might be able to hold off on blanket restrictions until 100 degrees or something like that. Given how much signaling equipment is already out there on the line now I doubt this would require brand new supporting communications infrastructure. (Or at least so one would hope).

There is one other idea that comes to mind. Not sure which would be cheaper. Install beacons on the line that use GPS and communicate via cell or satellite their relative position. They could probably be self powered using a solar cell the size of a hand. If you're using really precise GPS (WAAS enabled) you would know almost immediately if the line shifted more than an inch or two. Given how much distortion often happens with heat kinks you probably wouldn't need to install more than one beacon every quarter mile or so. Still not as inexpensive (and perhaps as safe) as simple speed restrictions.

Sometimes heat kinks don't manifest until the weight of the train disturbs the equilibrium of the track. It used to be that when it didn't kink till the weight of the train was off it, the caboose crew could report it but the train itself would be OK. When it kinks as the loco is approaching, drama has always ensued.

Pan Am also puts heat restrictions on their west end as well (25mph) in the same heat. There were a lot of problems with sun kinks this summer between Athol and Fitchburg.

jbvb wrote:Sometimes heat kinks don't manifest until the weight of the train disturbs the equilibrium of the track. It used to be that when it didn't kink till the weight of the train was off it, the caboose crew could report it but the train itself would be OK. When it kinks as the loco is approaching, drama has always ensued.

So perhaps part of the safety element of speed restrictions during heat is also to lower the amount of force exerted on the tracks by passing trains?

gokeefe wrote:

MEC407 wrote:I think part of the issue is that places like NC and FL don't have quite the same temperature extremes that we have up here, and also that the rails in those areas are heated to a higher temperature when they are initially laid, in order to take into account the average operating temperature when the rails are in service. If we heated our rails to the same temperatures that the NC and FL track crews used during the tracklaying process, then we'd get into trouble in the wintertime.

(All of the above is how it was explained to me by railroaders. Corrections welcome if I got it wrong in translation.)

Better to be safe than sorry, I suppose. Several years ago (early 2000s) there was a derailment on the St. Lawrence & Atlantic due to a heat kink on a hot day. Would the engineer have been able to stop short of the kink if a speed restriction had been in place? We'll never know for sure, but it's possible. Likewise, a passenger train has a better chance of being able to stop short of a kink at 40 than it does at 60-79.

MEC407,

Thanks for the explanation. Safety must always come first and it makes a great deal of sense that our climate extremes would cause these problems. Maybe at some point in the future NNEPRA will arrange for funding to PAR to install strain gauges etc. At least then the railroad might be able to hold off on blanket restrictions until 100 degrees or something like that. Given how much signaling equipment is already out there on the line now I doubt this would require brand new supporting communications infrastructure. (Or at least so one would hope).

There is one other idea that comes to mind. Not sure which would be cheaper. Install beacons on the line that use GPS and communicate via cell or satellite their relative position. They could probably be self powered using a solar cell the size of a hand. If you're using really precise GPS (WAAS enabled) you would know almost immediately if the line shifted more than an inch or two. Given how much distortion often happens with heat kinks you probably wouldn't need to install more than one beacon every quarter mile or so. Still not as inexpensive (and perhaps as safe) as simple speed restrictions.

Have any railroads invested in strain gauges, GPS technology, etc. to monitor the forces on their rails, though? When it was mentioned above I interpreted it as a passing notion, not an established practice. It doesn't sound like the kind of thing that a profit-motivated railroad would invest in, really. The technology may not be out of reach, but integrating it with hundreds or thousands of miles of railroad would be a non-trivial capital investment versus just slowing the trains down for a period of mere hours or a day.