WMATA Green Line derailment

[aegrotatio]

In the latest black eye to hit WMATA, several cars of a Green Line train partially derailed near West Hyattsville Station.  This weekend trains are to be restricted to 35 miles per hour on suspicion that our extreme heat contributed to the derailment.

 

[blue streak 1]

 

It no longer a suspicion.  It was a heat kink.  VRE ISSUED A newsletter with a picture of the green line heat kink.  see belowi

 

 

Weekly Newsletter Heat, track work and trains....

Tie Gangs Norfolk Southern surfacing and tie gangs are currently working on the track, beginning at Broad Run and working their way northward through VRE territory. This work began on Saturday, July 7 and will continue until Monday July 23rd. Work will take place primarily on Saturdays and Sundays, with a 5 to 6 hour period on Monday that will be used to finish the area and turn it back over to passenger and freight traffic. As we saw yesterday, the work is focused on Track 1, which is the track nearest the platforms and the one we use for boarding passengers. This, unfortunately, resulted in some delays for our morning trains ranging between 10 to 27 minutes. Train 321 which is a turn train that comes back from Union Station to operate as the final northbound morning train (332) was delayed getting back to Broad Run because of the need to work back through the speed restricted areas.  That resulted in a 42 minute delay for 321 and a 60 minute delay for 332. Surfacing and tie gangs are critical to the safe and efficient operation of any railroad. In this case, NS expects to replace around 20,000 ties in the VRE territory. The tie and surface gangs replace worn ties and at the same time, work on the base foundation and ballast that help hold the ties and rail in place.  Once the ties have been replaced, a certain amount of tonnage has to pass over the rails at restricted speeds to make sure that any needed settling can occur. Speed restrictions begin at 10 mph and then gradually increase back to regular speeds once enough traffic has been through the area. That is why you will still find some speed restrictions on the line today. We can expect similar delay issues for the next two Mondays on the Manassas line as the gangs complete this work. The later morning trains have the most potential for delays, so if possible, please try to adjust your schedule to catch an earlier train and minimize the inconvenience. We will continue to work with NS and Keolis to do everything possible to keep delays to a minimum. As mentioned above, tie gangs are critical to the safe operation of the railroad. The extremely hot weather that we have experienced for the past couple of weeks has brought on the need for frequent heat restrictions. In July, 2010 we did an article on heat restrictions and the potential damage of “Heat Kinks.” The periodic replacement of ties and firming of the base and ballast on a railroad can help prevent the formation heat kinks. This is why we sacrifice On Time Performance on occasion to get this work done.  As we have always stated, safety of our passengers and crew is our number one priority. The unfortunate incident that occurred last Friday on Metro’s Green Line is a stark reminder of the potential danger of heat kinks. We have revisited our previous article and are including it here to reinforce the point that extreme heat can cause real damage and we are more than happy to comply with heat restrictions issued by the railroads in the interest of safety. From VRE Update, July 2010 This past year has been the warmest on record, and in July and August in the DC area, that means hot. For the railroad, hot can be a problem. If you’ve looked in the papers recently you might have found an article or two about heat kinks or an article about heat related speed restrictions. In the grand scheme of things, heat restrictions do not really count for that great of delay (8 to 10 minutes at the most which can often be made up). However, when it is hot enough for heat restrictions to be needed, it is also hot enough for the temperatures to affect mechanical equipment such as signals and switches along the tracks. The combination of these two factors, possible switch or signal issues and slow speeds can, unfortunately, result in some delays. But why the need for the restrictions? Trains ride upon two ribbons of steel. This steel has been metallurgically engineered to be strong and stable, yet incredibly flexible. This flexibility, which serves well in the creation of curved track and during periods of exceptional cold (when rail remains strong) can sometimes be a double edged sword. When many miles of rail are subjected to intense heat, the rail becomes extremely hot. Since the rail is firmly anchored into the wooden or concrete railroad ties, it has little room to move, keeping trains moving at great speeds stable. However, on hot days, heat causes expansion and the superheated rail can increase in length over a great distance. Since there cannot be any gaps in a rail to allow for this expansion, pressure builds up in the rail itself as it tries to expand lengthwise but cannot. With no room to expand, the rail can bow outward like a plastic ruler squeezed at each end between your fingers. It pulls the wooden ties right out of the stone track-bed with it and creates a sharp curve. When this occurs, the track has what is known as a “sun kink” or “heat kink”. These occur without warning and if unchecked, can create a very unstable operating situation for a train. When railroad maintenance officials see that conditions may be right for such a situation, they issue heat warnings and our trains end up traveling slower, since fast travel speeds add to the friction which adds to the heat. When trains slow down, there is less friction and therefore less heat which reduces the bending of the rail. While no one likes to be delayed, even if it is only 8 to 10 minutes, the use of speed restrictions is definitely a case of being “better safe than sorry”. Photo from Friday’s Metro Green Line derailment.

[endeavour]

Glad no-one was hurt. Here in Oz land we have big problems with this sort of thing. Apart from constant vigilance, what is the solution?

[aegrotatio]

VRE is a class act.  The like to keep passengers informed about these really mundane topics that we railfans eat up.  They posted photos of the washout from last year's floods, too.

Another interesting tidbit from FOX5: "Last year Metro began replacing its tracks with more heat tolerant rails. The new tracks can withstand temperatures between 85 and 105 degrees. The track replacement project is part of a multi-year effort by Metro. The section where the derailment occurred still has the old rails, which are designed for temperatures of only 80-95 degrees."

...and "It also discovered a second heat kink on the green line between Branch Avenue and Naylor Road."

 

 

[BaltACD]

aegrotatio

VRE is a class act.  The like to keep passengers informed about these really mundane topics that we railfans eat up.  They posted photos of the washout from last year's floods, too.

Another interesting tidbit from FOX5: "Last year Metro began replacing its tracks with more heat tolerant rails. The new tracks can withstand temperatures between 85 and 105 degrees. The track replacement project is part of a multi-year effort by Metro. The section where the derailment occurred still has the old rails, which are designed for temperatures of only 80-95 degrees."

...and "It also discovered a second heat kink on the green line between Branch Avenue and Naylor Road."

 

 

Rails are not more or less heat tolerant.

The difference is the 'nominal temperature' when the rail is laid.  On one carrier I am familar with, the nominal temperature on the Northern part of it's system is 85 degrees.  On the Southern part it is 95 degrees - the rail is the same on both parts of the property.  Rail gangs will heat and or cool rail to the nominal temperature when fastening it in place.