All Things WMATA 7000 Series

"dcmike"

It shouldn't be an issue. The hardware is there, both carborne and wayside, to facilitate this and many other new-to-WMATA functions built in to the 7000 cars. It's known as TWDT, or train to wayside data transfer - note this is completely unrelated to TWC (train to wayside communication), a component of our ATC system. TWDT uses standard wifi, which has been installed at nearly every station at this point. Improving the passenger information displays is very, very low priority currently. There are still a substantial number of outstanding open engineering issues with the basic car design yet to work through. We've made very little progress towards implementing automatic transmission of car event and fault logs - the killer app so to speak for TWDT. If that ever becomes a reality, the next step will be rolling out automatic software updates.

The question I have is the protocol used IP or something proprietary. Same question about the network aboard the cars.

TWDT is standard TCP/IP over wifi.

Network architecture aboard the cars gets a bit more complex. There are actually three logical networks, each one broken down a bit further:

1. ETN (Ethernet Train Network) facilitates non-operational communications. This is a standard TCP/IP (IEEE 802.3) network. It handles CCTV, event logging, monitoring of non-critical systems, passenger information data (PA announcements, etc), TWDT, and the like. There are three parts to this network: a car network, a married pair network, and a train wide network. Components (nodes) are connected point to point to network switches which forms the car network. The switches are connected to one another in a ring topography to create a redundant backup. The train network is the backbone for all IP networks.

2. TCN (Train Control Network) is the command and control network. This is a standard MVB (multifunctional vehicle bus), or IEC 61375 network. This network handles all critical train functions such as propulsion and braking commands, door controls, ATC interface, etc. It is fully dual redundant; that is, there are two independent MVB networks each with their own networking hardware and cabling interfacing each component. This increases reliability as only one network need be functional at any given time. This network is formed using a wired train bus that connects a gateway in each individual car. Components then connect to the gateway to form the local MVB.

3. DTN (Discrete Trainline Network) is a vestige of the standard binary trainline system used on all legacy cars. While the old cars had 80+ trainlines, the 7000s have just 7. These are used strictly for independent verification of commands that are handled by the TCN. It's a safety feature that double checks the validity of certain critical control functions.

There's technically a fourth as well, but not really important to vehicle operation. Cars designated as B2 cars are equipped with a component known as a vehicle-track dynamic monitor. These cars use a series of truck-mounted sensors to collect information about the car's interface with the track. This data is then transmitted via cellular link to a vendor where it is processed and analyzed using proprietary algorithms. Certain anomalies will trigger a notification to the track department superintendent for remedial action. This system does communicate with the train over the ETN, but only to report its own diagnostic info. This type of system is new to transit but widely deployed at freight railroads.

dcmike wrote:Cars designated as B2 cars are equipped with a component known as a vehicle-track dynamic monitor. These cars use a series of truck-mounted sensors to collect information about the car's interface with the track. This data is then transmitted via cellular link to a vendor where it is processed and analyzed using proprietary algorithms. Certain anomalies will trigger a notification to the track department superintendent for remedial action

Is there even a track superintendent to send that notification to now? Is this doing some of the function similar to that of a TGV? What is it monitoring?

The VTDM is intended to be a passive supplementary method of identifying track discrepancies. I don't have the documentation here at home with me, but if I recall correctly the instrumentation is quite limited: a few accelerometers and maybe an acoustic sensor. Here is an all too brief marketing brochure from the vendor: http://ensco.com/sites/default/files/20 ... -ENSCO.pdf" onclick="window.open(this.href);return false;

The TGV is a far more comprehensive tool that includes laser measuring devices, ultrasound, thermal imaging, etc.

Thanks for sharing your knowledge. Do you know how location is determined when trains are underground? The brochure says the monitor uses GPS for location. Also, do you know if there are truck defects that could be detected by comparing data from different cars for the same section of track? I have no idea if that would be worth the cost of equipping all of the trucks with one of these monitors. Just curious.

The system has custom built software that interfaces with the carborne ATC system over ethernet. The ATC system provides the last platform ID code received from TWC plus a distance counter calculated from axle mounted tachometers. These two values can be used to determine location in the absence of GPS. I'm told it was found to be reliably accurate within ± 2 ft during testing.

There is a wayside system known as a Truck Performance Detector that does precisely what the second part of your question is asking about.

dcmike wrote: There is a wayside system known as a Truck Performance Detector that does precisely what the second part of your question is asking about.

That was interesting. Where is it installed, Brentwood?
Is there an effort to rotate all rolling stock through that yard regularly?

So how easy will it be to hack a 7000 series car?

I would love to change the signage on the trains to various Dan Stessel moronic quotes, all ending with "you're welcome".

Is it true the added weight of the 7k cars is causing some problems?

I saw someone say this in a blog comment and I was wondering if anyone else heard this.

This morning I road a 7000-series train on Green line that included car 7255. So we're just 54 cars away from the magical (or at least magical in my mind) 7300.

Its not just in your mind. That really is THE magical number. That number represents the following:

• *The moment the 7k offically becomes the largest fleet series Metro has ever had in history
  *The moment they pass the original order of 1k cars
  *The first time any Metro rail car has ever had the number 3 following the series number (last 1K car is 1299)

"JDC"
This morning I road a 7000-series train on Green line that included car 7255. So we're just 54 cars away from the magical (or at least magical in my mind) 7300.

Actually the magical number is 7299 as the 300 1k cars were numbered from 1000 > 1299. If you include the 64 cars for phase I of the Silver line the magical number becomes 7363.

What we're talking about here is when the 7000 series becomes the largest fleet size in Metro's history.

Sand Box John wrote:"JDC"
This morning I road a 7000-series train on Green line that included car 7255. So we're just 54 cars away from the magical (or at least magical in my mind) 7300.

Actually the magical number is 7299 as the 300 1k cars were numbered from 1000 > 1299. If you include the 64 cars for phase I of the Silver line the magical number becomes 7363.

No I think its 7300. That is when the 7K become larger than the original fleet. It is also the first Metro rail care to ever have the number 3 after the series number. I think 7300 is a more significant number than 7299.