Stopping distance question.

[BLR Guerrilla]

Guys for specific train how do you figure out stopping distance? I mean in real life. Do they know approximately what this distance is? It's not like a car, stopping distance can be several KM.

[Captainbob]

First thing I do when driving a new train is to test the braking action.

[simonmd]

I don't know if there are actual tables in real life that a driver would refer to but I doubt it, the metal to metal contact is so variable, even a change in temp' would change how the train grips the rail. The there's a huge variable in weight that passenger trains have that would change the train's dynamic from station to station. I suppose most drivers will just get a feel for their train, I have just been driving the Class 378 and found that an 80% brake applied at 0.26 from the stopping point at 50mph seems to work quite nicely. In real life I can imagine this changing quite a bit.

[Glenn]

Actually it is (was in my time as a train driver 70s & 80s) just the same as a car. How does a car driver know the stopping distance of his / her car? There are no tables of any kind. It is purely down to practise. practise years of experience and skils learned. Only difference with a train is that it is bigger, heavier and takes that much longer to stop, but the same rules apply -- practise. practise years of experience and skils learned. (about 5 years in my case). That said of course, I have no experience with the modern plastic computer controlled people shifters. Maybe computers assist the driver?

[BLR Guerrilla]

Interesting to know how this is done in real world.

I did similar stuff. Made a table of stopping distances from 200kph to 0 (delta 20kph). Otherwise I miss deadlines.

I am not sure if game mimics weight of passengers but after 3 station in scenario in Germany my train will have wheel slippage if I accelerate too fast! Initially I can pretty much do 50% then after short delay 100%. Later on I have to be more careful.

So I figured out breaking % and throttle % to use at different speeds. I think one thing game is missing is feel of acceleration. So next best thing is to use tables (and circle on the bottom left corner which shows acceleration in 4 directions).

[BLR Guerrilla]

Originally posted by glennives60:

How does a car driver know the stopping distance of his / her car?

It is true but stopping distance of a car is quite small compared to a train. Also cars don't do tight schedules-driving like trains in DE and CH are doing.

I never drove real train though. So I am not sure how all this works. Especially when there is a very tight schedule.

[simonmd]

Yes but the principle that this guy was trying to compare it to is the same. You are bringing a moving object to rest from a certain speed, doesnt matter if it's 1 ton or 1000 tons, they will still have predictable behavior. One advantage a train has over a car is they dont need to worry about what other traffic is doing with regards to breaking, and they drive on a fixed route, so its certainly possible to pick marker points en-route that can be used as braking points, either physical ones or just distance from the station in the HUD as I suggested above. Then the driver can adjust with more or less force as they enter the platform depending on the conditions.

[BLR Guerrilla]

One difference is this:

When you stopping a car you are seeing the place where you have to come to a full stop. Like a traffic lights. So you can adjust accordingly (it's all visual).

In a train this place might be really far away. In the game passenger train takes ~2.5km top stop from 200kph (aggressive breaking, empty train). So you don't really see the stopping point until some time later. So it's not really visual.

Well, yet again you might be right, I never drove a train. I do fly planes and drive cars though.

[Glenn]

Originally posted by BLR Guerrilla:

One difference is this:

When you stopping a car you are seeing the place where you have to come to a full stop. Like a traffic lights. So you can adjust accordingly (it's all visual).

In a train this place might be really far away. In the game passenger train takes ~2.5km top stop from 200kph (aggressive breaking, empty train). So you don't really see the stopping point until some time later. So it's not really visual.

Well, yet again you might be right, I never drove a train. I do fly planes and drive cars though.

But after many years practise and skills learning, it becomes un-necessary to 'SEE' the actual stopping point. You instinctively know that 'it is just around the next 2 bends and under the bridge' (or whatever) and bring the speed down accordingly. In fact stopping tables become rather arbitrary, because there are so many variable factors including weather & passenger numbers (or laden / empty freight). I have even been braking on some routes where it has become impossible to stop (at least within the reaquired distance) because of rail conditions.

Do you (BLR....) by any chance live in the USofA where 99% of all roads are straight lines? Over here in England, there are ALWAYS countless curves & bends in the road where it is simply not possible to 'SEE' those traffic lights or many other stopping points!!

[BLR Guerrilla]

Originally posted by glennives60:

Do you (BLR....) by any chance live in the USofA where 99% of all roads are straight lines? Over here in England, there are ALWAYS countless curves & bends in the road where it is simply not possible to 'SEE' those traffic lights or many other stopping points!!

I do but you shouldn't trust Top Gear much. Come and drive from Seattle to San Francisco on I101. Don't forget to bring a fun car (MX5 or something like this). Many-many-many turns, spectacular views.

Another good place to drive is higway 14 on Vancouver island (BC, Canada) from Victroria to Port Renfrew. You will have to stop to piss on your brakes if you do it properly. Very few straight pieces.

And speed cameras are illegal in WA, USA and BC Canada (last time I've been there, not sure if they changed anything, I live in USA). ;)

[BLR Guerrilla]

Originally posted by glennives60:

But after many years practise and skills learning, it becomes un-necessary to 'SEE' the actual stopping point. You instinctively know that 'it is just around the next 2 bends and under the bridge' (or whatever) and bring the speed down accordingly.

Thanks for the info!

[Jackson]

Hah.. yea. There are few roads around here (Western WA state) that are all that straight for very long and you can always, ALWAYS see stop lights well in advance. Otherwise you'd have people getting killed all the time. If there is not a lot of room before a light, the speed limit will be lowered to force you slower.