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Re: CN Derailment in Port Huron Tunnel
Posted: Fri Jul 05, 2019 3:07 pm
by GP9R
Saturnalia wrote:hoborich wrote:They dragged the DPU out at some point Monday afternoon, from what was posted on Facebook.
So, there is no crew or engineer on the DPUs?
Distributed Power Units are not manned, they are radio-controlled from the lead locomotive. This is the distinction from the manned helper locomotives of yore. DPUs are generally intended to stay on for the entire run of the train from origin to destination, rather than just over a certain segment of the road as is typical with manned helpers.
A few more notes on the discussion above:
As far as losing communication with the DPU, I'd imagine CN has installed repeater antennas inside the tunnel to handle DPU, EOT and PTC communications. Most tunnels of that sorta length get that treatment, and I'd imagine due to the sag in the tunnel it would be even more necessary.
It does sound like Canada will lead the investigation due to the point of derailment determined to be on the Canadian side of the border, NOT because the train hadn't made it 100% into the US yet.
As for not allowing DPUs in the tunnel due to the grade, that's kinda absurd. DPUs are usually added specifically to help longer trains tackle grades and curves. Running 12000' manifests in the tunnel would probably be more difficult without DPUs than with them.
<begin speculation>
The primary issue running long trains through the tunnel, and potential cause of the wreck, is the play in slack, whereas the train is stretched coming out of the tunnel but bunched up going in. Traditionally crews would probably have used the "stretch-braking" technique with a slight brake pipe reduction to keep the train all stretched out by slightly applying the brakes throughout the train. But with the DPU involved, they likely keep the DPU in dynamic braking until it reaches the bottom of the tunnel, thereby keeping the train stretched out, as the headend would begin pulling somewhere around the bottom of the tunnel. These are my presumptions, I should add, I have never spoken with anybody who has operated a train through this particular tunnel.
Thus, it is possible that the engineer flubbed up the coordination between the headend and DPU power. Perhaps this caused a pull-apart, and subsequent collision inside the tunnel, as the headend (going uphill) would slow down faster than the still-descending rear-end. A hit at high enough speed could cause cars to derail, and it would be on from there.
Other causes could lie in track conditions, a mechanical failure such as a broken wheel, or the aforementioned failure of DPU communication inside the tunnel.
<end speculation>
PTC Ends at Tappan, Tunnel begins at Port Huron/16th St(As far as control points go)
Not sure if there are DPU Repeaters in the tunnel or not. But there is a plan B for DPUs
You cannot stretch brake in the tunnel, especially on long trains because it will not release fast enough and you either stall, or rip the train into pieces.
You cannot run a DPU engine in Dynamic brake and the head end in power, the software will not allow it, becuase it would be easy to rip the train apart with it
Re: CN Derailment in Port Huron Tunnel
Posted: Fri Jul 05, 2019 3:47 pm
by Saturnalia
PTC Ends at Tappan, Tunnel begins at Port Huron/16th St(As far as control points go)
Not sure if there are DPU Repeaters in the tunnel or not. But there is a plan B for DPUs
You cannot stretch brake in the tunnel, especially on long trains because it will not release fast enough and you either stall, or rip the train into pieces.
You cannot run a DPU engine in Dynamic brake and the head end in power, the software will not allow it, becuase it would be easy to rip the train apart with it
Thanks for this info, GP9R! Just the sort of info missing from the discussion.
I’m sure many of the crews could write a book on operating in the tunnel. Always fun to hear how it’s actually done.
So is the usual method to just run dynamics until the head end gets past the bottom, then start notching up until ultimately you reach pretty much full go as the headend makes the summit?
Re: CN Derailment in Port Huron Tunnel
Posted: Fri Jul 05, 2019 11:14 pm
by hoborich
Why not put the DPUs mid train, uncouple the train and take it across in two pieces and recouple on the other side, and avoid a lot of potential problems. It seems to me to be pennywise and pound foolish, as they used to say, to take those land barges across in one long train, with or without DPUs. It may work most of the time. But the cost of this cleanup would pay for a lot of crews across the river.
Re: CN Derailment in Port Huron Tunnel
Posted: Sat Jul 06, 2019 10:07 am
by Stinger4me
That might involve too much "common sense" and/or "simplicity".
Re: CN Derailment in Port Huron Tunnel
Posted: Sat Jul 06, 2019 10:28 am
by bnsfben
Anyone know if the tunnel has re-opened?
Re: CN Derailment in Port Huron Tunnel
Posted: Sat Jul 06, 2019 11:54 am
by CR900945
Why don't we wait for a preliminary cause to be revealed? The speculation concerning the DPU is just that, speculation. Without confirmation that the DPU malfunctioned, it is premature to suggest a change in operating practices. Something else could have caused this, perhaps poor train make-up regarding placement of empties and loads. Train handling could be a factor. A wheel, axle, or drawbar may have failed and the situation was made worse by the presence of the DPU. On occasion, we have seen a number of things go wrong at the same time. This one will absolutely be a challenge to sort out and pinpoint an exact cause.
Re: CN Derailment in Port Huron Tunnel
Posted: Sat Jul 06, 2019 9:06 pm
by 12Bridge
bnsfben wrote:Anyone know if the tunnel has re-opened?
Still dragging wrecks out. Then all the track needs to be rebuilt.
Re: CN Derailment in Port Huron Tunnel
Posted: Sat Jul 06, 2019 10:12 pm
by GreatLakesRailfan
12Bridge wrote:bnsfben wrote:Anyone know if the tunnel has re-opened?
Still dragging wrecks out. Then all the track needs to be rebuilt.
From the sound of what I heard on the scanner a little while ago, they're onto the track rebuilding part. There was video on Facebook earlier of panel track with concrete ties on flatcars being shoved (gently) from the US side into the tunnel. 4903 is still down in the vicinity of the tunnel, possibly with the panel track flats, or possibly with some ballast. There was an excavator headed I to the tunnel with the past hour or so, but there was confusion as to whether or not there was ballast following that excavator. One way or another, I'm pretty sure there will be ballast moving into the tunnel in the very near future.
There were several videos of the wreckage being removed posted on Facebook today in the past couple days. It was interesting to see that not only was there at least one crushed boxcar with an aluminum ingot load, but the ingots apparently held their shape while the rest of the car is pretty much just scrap metal now.
There was some mention on Facebook that there were loaded autoracks placed in front of the DPU, which may have contributed to the severity, but from the look of the stuff that apparently was in front of the DPU, all the DPU did was make a bad situation much worse.
Re: CN Derailment in Port Huron Tunnel
Posted: Sat Jul 06, 2019 11:11 pm
by hoborich
What Facebook site? Thanks.
Re: CN Derailment in Port Huron Tunnel
Posted: Sun Jul 07, 2019 8:51 am
by GreatLakesRailfan
hoborich wrote:What Facebook site? Thanks.
Tim's Railfan Group.
Re: CN Derailment in Port Huron Tunnel
Posted: Sun Jul 07, 2019 8:09 pm
by mowingman
A friend of mine in the derailment business said this was a bad one. He said Cranemasters, Hulcher and Winters were all involved in the cleanup. Possibly Corman also, but not sure of that. He said a lot of walking was involved in that mess just to get personnel in to the wreck.
Re: CN Derailment in Port Huron Tunnel
Posted: Sun Jul 07, 2019 9:01 pm
by hoborich
Something else could have caused this, perhaps poor train make-up regarding placement of empties and loads. Train handling could be a factor. A wheel, axle, or drawbar may have failed and the situation was made worse by the presence of the DPU.
Given all of the above possibilities, I think this was bound to happen sooner or later. Just my opinion here, but taking those land barges through the tunnel in one long train is asking for trouble, with or without the DPUs, given the downhill and uphill grades involved, and the sudden change from downhill back to the uphill side. Frankly, I think they have just been lucky up until now.
Re: CN Derailment in Port Huron Tunnel
Posted: Tue Jul 09, 2019 6:52 am
by Super Chief
Given the fact these are out of pocket dollars as I don't think railroads carry insurance for derailments you would have thought it would be a priority to maintain and inspect this important link in the system?
Re: CN Derailment in Port Huron Tunnel
Posted: Tue Jul 09, 2019 9:41 am
by Steve B
Super Chief wrote:...you would have thought it would be a priority to maintain and inspect this important link in the system?
Nothing disclosed so far suggests that CN hasn't been doing that all along.
Re: CN Derailment in Port Huron Tunnel
Posted: Tue Jul 09, 2019 9:54 am
by SD40-2
Tunnel is open for business again as of last night
Re: CN Derailment in Port Huron Tunnel
Posted: Tue Jul 09, 2019 11:32 am
by blueheron13
Apparently still a little work to be done. If anyone follows Tim Holmes and his railfan group on Facebook, he is posting regular updates of the equipment (and work trains) going in and out of the Port Huron side of the tunnel.
Re: CN Derailment in Port Huron Tunnel
Posted: Tue Jul 09, 2019 5:03 pm
by blueheron13
Just prior to 4:00 PM, M384 was the first through the reopened tunnel. This was apparently the train that went up the Mount Clemens Sub a couple of nights ago.
Re: CN Derailment in Port Huron Tunnel
Posted: Tue Jul 09, 2019 7:17 pm
by railrod1949
blueheron13 wrote:Just prior to 4:00 PM, M384 was the first through the reopened tunnel. This was apparently the train that went up the Mount Clemens Sub a couple of nights ago.
It have CN engine 2936 leading 3096 trailing and DPU CN engines 2303 and 2518. With a London, ON, Canada crew handling it, On duty at Port Huron.
Re: CN Derailment in Port Huron Tunnel
Posted: Fri Jul 12, 2019 7:17 am
by GreatLakesRailfan
Steve B wrote:Super Chief wrote:...you would have thought it would be a priority to maintain and inspect this important link in the system?
Nothing disclosed so far suggests that CN hasn't been doing that all along.
Once in a while I hear a track inspector in the tunnel (i.e. I happen to be listening at the right time), but while I've seen plenty of work done at the east end of the yard, I don't recall seeing or hearing of any work taking place on the track/infrastructure on the approach to or in the tunnel. That's not to say that nothing has been done- it's pretty easy to see stuff taking place out in the open. Not so much when the view of the approach to the tunnel is choked with tall vegetation and the tunnel itself is...well...a tunnel. It will be interesting to see what effect this has on the stock price and earnings expectations for the year.