How are consists put together?

I'm curious as to who's making the decision to make a few 7-car sets, a few 6-car sets, and a bunch of 5-car sets and why? Why don't they just settle on 6-car consists? They shift around the lines constantly and it doesn't seem like the 7-car sets are lined up for just the high-volume runs, so is there a reason for this or not. And this also comes down to the ridiculousness of when we had that 4-car set with a bi-level in it, and I think we had a 7-car set somewhere while that was going on... really?

Note: This likely only applies to the North Side. Unlike some sides -- not mentioning any sides here -- we don't get strands of 7 bi-levels.

There are required consists set by the MBTA. There has to be x amount 7 car sets, x amount of 6 car sets. There has to be 5 car sets because some layover tracks at the outlaying points can only hold 5 car sets. Rockport has 2 tracks for example that can't hold more than 5 cars. For the most part the 7 car sets do operate on busy trains at rush hour. But because there are only so many sets, the 7 car sets have to run at off peak as well.

Actually, SERy, unless they changed it since I was working at MBCR, the requirement is for a certain minimum number of seats per train. This does tend to translate to being a specific number of coaches, but as Urbie noticed, on some trains a bilevel can substitute for a pair of flats.

Well the requirement could be in the seating numbers, but it still translates into needing sets to be certain sizes in the end.

How big a deal is it to unhook these cars? Suppose they just wanted to use power and 2 cars off peak hours, could they drop the remaining cars and run, and then pick them up for peak hour use.This all supposes, of course , that there was an area somewhere safe to do this and not have the cars in the way.Or is this a no-no due to rules and regulations? I just remember the old New Haven running just a few cars.

Teamdriver wrote:How big a deal is it to unhook these cars? Suppose they just wanted to use power and 2 cars off peak hours, could they drop the remaining cars and run, and then pick them up for peak hour use.This all supposes, of course , that there was an area somewhere safe to do this and not have the cars in the way.Or is this a no-no due to rules and regulations? I just remember the old New Haven running just a few cars.

The making and breaking of consists involves disconnecting cables for Head End Power, Multiple Unit control from the cab car, the communication cables, and of course the air brake lines. The cab car must be at the end of the train opposite the locomotive to lead the train inbound, and then there's other rules about a car with a restroom being next to the engine to line up with the mini-high platforms.

Safely switching this consist would take some time, my uneducated guess being at least 10-15 minutes, since the train would be broken into three pieces (cab car on the main, locomotive+bathroom car+other coaches, and set-out cars) and make a minimum of four moves if this were done on a trailing point spur. Each cut would need a handbrake set when not connected to the locomotive, and proper safety procedures for switching would need to be followed.

This isn't all that much work, but it's considerably more than what happens now. Also, where would these excess cars be stored?

It's just so much easier and cheaper to pull a few empty cars on off-peak trains.

I guess it is a tad more complicated than this.........

.http://www.youtube.com/watch?feature=pl ... FbooSwEim8

One of the operational advantages of the Budd RDCs that both the New Haven and Boston & Maine used extensively in Boston commuter service (and which lasted into the MBTA era) was that they could be quickly combined and detached. Both railroads ran a lot of single car RDC trains off-peak in those days of lower ridership, and longer trains at rush hours. In fact the New Haven had a few runs where RDC trains out of South Station would split en route to serve multiple destinations (like reaching both Hyannis and Wood's Hole with a single Cape Cod train from South Station). It always seems kind of wasteful for me to see six and seven car trains running around with just two cars open, but other commuter rail systems do the same thing since apparently the labor cost for switching is less expensive than the added fuel cost and wear associated with fixed consists of rush hour length.

Teamdriver wrote:How big a deal is it to unhook these cars? Suppose they just wanted to use power and 2 cars off peak hours, could they drop the remaining cars and run, and then pick them up for peak hour use.This all supposes, of course , that there was an area somewhere safe to do this and not have the cars in the way.Or is this a no-no due to rules and regulations? I just remember the old New Haven running just a few cars.

Plus as I recall a speed restriction on small sets: "The maximum speeds for lite engines, multiple lite engines, and equipment consisting of four coaches or fewer (passenger trains), or four cars or fewer (freight trains) are restricted to a Maximum Authorized Speed of 30 MPH." I assume this is still in effect?

On NJT, there is a consist management department that does this. They create consists and equipment manipulations based on ridership (number of cars and car type [single-level or ML]), train needs (some trains are better suited to MU's than electric push-pull sets, etc.), and final destination (MU's do not have the capability to switch voltage on the fly, so cannot be used on MidTOWN Direct trains or trains past Aberdeen-Matawan). I would imagine that MBCR has a similar department, although their job is somewhat easier, since they do not have to worry quite so much about a wide variety of equipment with different limitations.

TrainManTy wrote:

Teamdriver wrote:How big a deal is it to unhook these cars? Suppose they just wanted to use power and 2 cars off peak hours, could they drop the remaining cars and run, and then pick them up for peak hour use.This all supposes, of course , that there was an area somewhere safe to do this and not have the cars in the way.Or is this a no-no due to rules and regulations? I just remember the old New Haven running just a few cars.

The making and breaking of consists involves disconnecting cables for Head End Power, Multiple Unit control from the cab car, the communication cables, and of course the air brake lines. The cab car must be at the end of the train opposite the locomotive to lead the train inbound, and then there's other rules about a car with a restroom being next to the engine to line up with the mini-high platforms.

As Tyler said, breaking up and reassembling sets twice a day is not as easy as it sounds, unless you can ensure that you have a cab car buried in the consist where you will be breaking it.

MU cars are often broken up and reassembled several times during the day, so most have a special kind of "spear coupler" in which the brake line, HEP, and MU connections are made through the coupler itself. This way, connections can be made and undone by simply coupling and uncoupling the cars. However, these couplers can be more problematic to use (and I would imagine more expensive to maintain) than traditional knuckle couplers, which is why they are not widely used.
Here's a photo (not mine) of a spear coupler on a NJT Arrow III MU:
http://www.pjv101.net/film_bw/bw08/1423_300.jpg

Diverging Route wrote:

Teamdriver wrote:How big a deal is it to unhook these cars? Suppose they just wanted to use power and 2 cars off peak hours, could they drop the remaining cars and run, and then pick them up for peak hour use.This all supposes, of course , that there was an area somewhere safe to do this and not have the cars in the way.Or is this a no-no due to rules and regulations? I just remember the old New Haven running just a few cars.

Plus as I recall a speed restriction on small sets: "The maximum speeds for lite engines, multiple lite engines, and equipment consisting of four coaches or fewer (passenger trains), or four cars or fewer (freight trains) are restricted to a Maximum Authorized Speed of 30 MPH." I assume this is still in effect?

Yes this rule still exists. Except when running over CSX territory.

MU cars are often broken up and reassembled several times during the day, so most have a special kind of "spear coupler" in which the brake line, HEP, and MU connections are made through the coupler itself. This way, connections can be made and undone by simply coupling and uncoupling the cars. However, these couplers can be more problematic to use (and I would imagine more expensive to maintain) than traditional knuckle couplers, which is why they are not widely used.
Here's a photo (not mine) of a spear coupler on a NJT Arrow III MU:
http://www.pjv101.net/film_bw/bw08/1423_300.jpg[/quote]

Lots of interesting stuff, boys ! That spear coupler setup doesnt look like it would have as much give on curves as the knuckle type though.

Teamdriver wrote:Lots of interesting stuff, boys ! That spear coupler setup doesnt look like it would have as much give on curves as the knuckle type though.

Most of the required movement in such a coupler system happens at the anchors, where the drawbar mounts to the car's frame in a pivoting connection. The connection between the coupler heads must be tight and essentially motionless in order to maintain the connections between electric and pneumatic trainlines. In the posted photo you can see the rectangular cover on the bottom part of the coupler face, behind which are hiding many spring-loaded electrical contacts. The contacts on the opposing coupler faces meet up to complete the electrical trainlines.

This type of coupler is pretty much universal on rapid transit/light rail vehicles, so you can be sure that they work fine on tight curves.

There is also very little room at either North or South Station to shuffle consists and there are no switching crews. RDCs were very well suited to changing consist sizes readily. Split them apart and both sections are powered and can be moved independently.

Why did Budd stop manufacturing RDCs? Did the company go out of business, or was demand for rail equipment non-existent once the major railroads got rid of passenger service?