Some LUAS drivers are real "jerks" ...

bnt · 04-07-2013 12:43PM #1

... and I don't mean anything about their personalities. I've never spoken to one, and I'm sure they are very nice people. I'm referring to the way they drive the LUAS trains: jerkily. Some are worse at it than others.

Jerk is the scientific term for the rate of change of acceleration. (I'm not making that up.) We experience a constant acceleration all the time: that's what gravity does to us, and we're used to it. So we have little or no trouble dealing with a smooth, constant acceleration when we need to (within reasonable limits). A train that pulls out of the station smoothly is a good example: we can easily brace ourselves against it, even if we're standing up.

But when the driver rides the throttle like an on/off switch - as I've seen some LUAS drivers do, pushing it to the max for a second then back to zero - the acceleration keeps changing suddenly: we experience much more jerk. One second you're bracing yourself against strong acceleration, the next you're being thrown forward under deceleration. People and their things are being thrown around the carriage, kids are throwing up ... slight exaggeration there, but experiencing lots of jerk is a major factor in motion sickness. Even if you don't get queasy, it's still uncomfortable.

It's not just about the people, either. It's harder on the mechanics and electronics of the train, since it puts them through more "cycles". Joints are being stressed & released & stressed & released more then necessary. The power electronics has to work harder to keep up with the changing demands, producing more waste heat and reducing efficiency. Trams are supposed to be better for the environment, right?

Yes, I know, this is yet another "first world problem" ... but if there are any LUAS drivers or managers reading this: that throttle isn't an on-off switch, you can move it up and down slowly too. It's easier on the train and the people in it. No-one likes a "jerk". :cool:

tl;dr: smoother is better, m'kay?

biko · 04-07-2013 12:47PM

Yeah, I've experienced this in buses and trams all over the world. Especially when taking off.
They should put a scalding cup of tea in front of the driver, it'll keep them from jerking.

Dartz · 04-07-2013 12:47PM

Complaints about getting jerked by a tram driver?

I think the NSFW forum is over there somewhere ->

Sky King · 04-07-2013 12:52PM

Jerk is the scientific term for the rate of change of acceleration.

What about Jounce? That's the rate of change of Jerk.

They are jouncey bastards as well dont you know/

http://en.wikipedia.org/wiki/Jounce

RikkFlair · 04-07-2013 01:07PM

I can only ever imagine the work JERK when its shouted out loud by John McEnroe

Victor · 04-07-2013 09:36PM

biko wrote: »

Yeah, I've experienced this in buses and trams all over the world. Especially when taking off.

O_o, fancy flying trams. :pac:

04-07-2013 09:53PM

So if they decelerate, then does that mean they're technically a jerk off?

bnt · 04-07-2013 10:00PM

Well, if they don't decelerate, the train will hit the buffers, almost as hard as this thread did ...

B.A._Baracus · 04-07-2013 10:08PM

Did you really need to explain the concept of "jerk" to people :pac:
I mean we've all heard the expersion "to jerk a car"

bnt · 04-07-2013 10:18PM

Why explain? Because that's how I roll, sucka.

I've never tried to jerk a car, but I do know how to jerk chicken. Mmmmm ...

antodeco · 04-07-2013 10:21PM

Coincidence that Jerk and Luas both have four letters? I think not

Fecky the Ninth · 04-07-2013 10:25PM

Knock Knock! "Are you jerking it in your room again Fecky?
" No Ma, I'm scientifically changing the rate of acceleration"
"Oh okey then, keep it down in there."

Stereomaniac · 04-07-2013 10:25PM

Why not explain? My evening has been made a whole lot better now that I am remembering that beautiful piece of footage with John McEnroe, and I know the meaning of the word as well.

uch · 04-07-2013 10:43PM

I whole heartedly agree with something but I don't know what cause it's hard to read op

bnt · 04-07-2013 11:39PM

It wasn't so much explaining jerk as pointing out that it is a real, scientific measurement - units and all - which has a direct bearing on how stressful my daily LUAS ride is. Plus, it's proof that physicists actually have a sense of humour.

I have an Android tablet, if I want to I can spend €1.16 on an app to measure it. Though I would need to cable-tie the tablet to a rail to get anything useful, so ... nah.

PS is what I wrote in the OP really too hard to read? Maybe I should knock back a few whiskies before posting in AH again. :rolleyes:

dd972 · 05-07-2013 01:48AM

how did they all get those fecking jobs is what I'd like to know, you never see them advertised, are Veolia Ireland some sort of masonic lodge with funny handshakes going on?

Cookie_Monster · 05-07-2013 01:50AM

steel on steel is always going to cause issues like that as you try and control wheelslip

The Backwards Man · 05-07-2013 02:21AM

It's impossible to handle something as long, sleeek and volatile as a train without jerking it every now and again.

bnt · 05-07-2013 01:20PM

Oh, I agree - but if that was all there was to it, it would happen all the time, not some of the time with some drivers. There's huge variation between them, which is how we know it doesn't have to be that way.

Some LUAS drivers are real "jerks" ...

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