Passenger M.U.'s

[al-in-chgo]

I hope this isn't purely an academic matter, but I am searching for the correct definition of "m.u." in passenger service.  Through context I have assumed for years that it means "multiple unit," and classically when I think of them I think of the Illinois Central (today's bi-levs or the green riveted jobs of the past), the original Metroliner, and trainsets that run on NJT (and many commuter systems) with electricity but without locomotives.

For one thing, is "m.u." identical with "trainset" or does the first term refer to electric only?  I am thinking in particular of the diesel-electric River Line that NJT runs from Camden to Trenton:  it has two coaches bound in the middle by an apparent "accordion" but not one that permits thru passage; it's where the diesel-electric works are.  Is it a trainset but not an "m.u."?  If not, is the deciding factor that it lacks direct intake of electricity or that the two passenger spaces don't interconnect?  Is whether or not it can be strung up in, well, "multiple units" with only one engineer a deciding factor too? 

At this level coming to a workable definition may just be dealing with semantics but as alternate forms of propulsion and hybrid energy-sourced trains and trainsets become more common, it will probably become more important, too. 

Anyone out there with an opinion (lol) ?   - a. s.

 

[artpeterson]

Hi Al -

MU and what gets correctly referred to as such has to "pass" that test of being capable of operating under the control of a single engineman (or operator or motorman or whatever) when coupled into a consist.  So for those NJT River Line cars, if they can be coupled into a multiple car train and controlled by one person in the head cab, then yes they're MUs; DMUs in this case.  The fact that you can't walk through the "bath" section within one River Line carset wouldn't necessarily determine MU or non-MU status.  As you said, the IC, South Shore and CTA cars are all EMUs, some of those are single cars, some married pairs.  Hope this helps!  Art

[al-in-chgo]

Hi Al -

MU and what gets correctly referred to as such has to "pass" that test of being capable of operating under the control of a single engineman (or operator or motorman or whatever) when coupled into a consist.  So for those NJT River Line cars, if they can be coupled into a multiple car train and controlled by one person in the head cab, then yes they're MUs; DMUs in this case.  The fact that you can't walk through the "bath" section within one River Line carset wouldn't necessarily determine MU or non-MU status.  As you said, the IC, South Shore and CTA cars are all EMUs, some of those are single cars, some married pairs.  Hope this helps!  Art

 

I think you did great -- put the most important distinctions up front where they belong. - a.s. 

 

[beaulieu]

The Stadler GTW 2/6 used on the NJT River line would be considered a single unit just like a Budd RDC. If you notice there are just 6 axles under the unit and the passenger sections cannot be disconnected from the power section, except in a shop facility, they are only supported by a truck at one end. The term used to describe them is a "Railcar", they can be a DMU if NJT chose to have them equipped that way. Passenger access from one section to another is not required for a MU.