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9 votes
Accepted

For train track, why does the ballast need "good drainage"?

There are a number of good reasons why the ballast layer needs to be free draining. The main objective of the ballast layer being free draining is somewhat tautologically to keep the water out of the ...
Big Luke's user avatar
  • 206
8 votes
Accepted

Is there any reason why "inner-flange" style train wheels are almost universal?

If you leave off the flanges and just use cones that are solidly connected to an axle, then cones that taper outward (get smaller as they go out) tend to be self-centering but undamped (or underdamped,...
TimWescott's user avatar
  • 2,682
7 votes
Accepted

How to notate the position of a train?

Speaking personally (as someone who deals with this sort of thing for a US Class I on a regular basis) -- operational and maintenance personnel find railroad locations the same way you and I find ...
ThreePhaseEel's user avatar
6 votes

Are rocket engines practical for commercial aircraft?

At a fundamental level, it should be clear that throwing stuff out the back is going to be less economical than sucking in stuff in the front and throwing it out the back faster. For one thing, the ...
Olin Lathrop's user avatar
  • 11.4k
6 votes

Why don't public transport networks have more routes to each terminal?

The main reason is economics. Who is going to pay for all the additional lines? The other part to this is, will the additional lines have enough passengers to make them profitable and sustainable? If ...
Fred's user avatar
  • 9,687
6 votes

Why don't public transport networks have more routes to each terminal?

Keep drawing combinations. You forgot Østerås to Vestli, Østerås to Bergkrystallen, and every other combination of possible origin and destination. This breaks down in a hurry. By the time you ...
Harper - Reinstate Monica's user avatar
6 votes

Why did Jersey barrier bridge rails become the dominant type of highway bridge rail?

I've done some research on New Jersey barriers a few years ago and came across this article by the FHWA. The basic operating principal of the barrier is to dissipate some energy and redirect and ...
ChP's user avatar
  • 623
5 votes

Why do trains not have a high-friction emergency braking system?

Another contribution to the issue, if you want to stop a train of any length in a hurry you would need to uniformly brake every car in a controlled way. If you excessively brake the forward part you ...
agentp's user avatar
  • 949
5 votes

Vehicle load factor discrepancies

I think you are possibly concentrating on the wrong thing. From your state.pa.us link: The VLF of a passenger car (.0004) is so small that cumulative pavement impact is essentially moot So, ...
AndyT's user avatar
  • 3,143
5 votes

Monorails - why even have them?

One of the factors is reduction of amount of infrastructure per kilometer (= cost). Monorail is usually elevated on pylons, which means little disruption to the land below (which, in case of normal ...
SF.'s user avatar
  • 6,105
5 votes
Accepted

Why do trains use the same wheels for staying on track and propulsion?

Trains do sometimes use different means for propulsion: Rack railways use cogs, and Funiculars use ropes I think the reason these are uncommon is that the available traction of smooth tracks is more ...
Alex I's user avatar
  • 175
5 votes

Speed breaker design

Shallow, wide speed bumps are easy fore slow traffic while offering more or less the same impact as narrow, high speed bumps. Because the impulse force remains the same for fast speed. They are having ...
kamran's user avatar
  • 22.5k
5 votes

Which is fuel efficient, roadways transport vs waterways transport?

Unfortunately, this question shares multiple similarties to the phrase "How long is a fish?"; meaning that the answer is very dependent on the assumptions, limitations and scope of your ...
ToxicOwl's user avatar
  • 369
5 votes

Why are expansion joints on prestressed concrete box girder bridges sometimes not located directly above the bridge piers?

Because the extension of the longer span past the column into a cantilever allows it to enjoy the benefit of the cantilever part's positive moment effect on the reduction of the midspan negative ...
kamran's user avatar
  • 22.5k
4 votes

Are rocket engines practical for commercial aircraft?

Economically a rocket engine will always lose out to a jet engine. We'll ignore solid fuel rockets, they are impractical for commercial air travel due to their fixed thrust and inability to turn on ...
Andrew's user avatar
  • 766
4 votes

For train track, why does the ballast need "good drainage"?

For both kinds of track, the answer is the same: to prevent the track from shifting as a result of freeze-thaw cycles. The idea with ballasted track is that water is not allowed to accumulate in the ...
Dave Tweed's user avatar
  • 6,904
4 votes

Is there any reason why "inner-flange" style train wheels are almost universal?

On a fast curve the outer flange ( on the inside of the curve) will lift off the rail and the train will leave the tracks. While an inner flange is pushed down onto the rail giving more stability.
blacksmith37's user avatar
  • 6,154
4 votes

What are these reflective triangles on the sides of train track rails for?

They are markers used for accurate position monitoring, without the need to close the tracks to trains and allow people to work close to them. All the markers can be scanned from a few fixed points (e....
alephzero's user avatar
  • 12.5k
4 votes
Accepted

What do we call these "transport frames made of wood" (обрешетки in Russian)

The English term for this is definitely crate.
Mike Waters's user avatar
4 votes

On the steam locomotives, why was the driver's cabin not located in the front of the boiler for better visibility?

There have been some locomotives with this design, it's called "Cab forward." As the article says, Southern Pacific railroad in the US had some cab forward locomotives, which solved crew ...
Ward - Trying Codidact's user avatar
3 votes

What should a road's traffic volume to justify the number of lanes?

"Vehicles per day" is a pretty bad metric to use. Instead you should look at rush hour and see how many vehicles are trying to get through. Every lane can carry 1800 vehicles each hour on a freeway. ...
ratchet freak's user avatar
3 votes
Accepted

Why use rectifier / inverter in locomotives?

To change varying AC to fixed AC .for example the alternator that is attached to the engine will output varying AC voltage, whose frequency would be different from the operating frequency or rated ...
Boris's user avatar
  • 166
3 votes

How to notate the position of a train?

In most cases a position on the track will be most useful as GPS probably won't have high enough resolution to indicate which line it is on if there are several tracks in parallel. Also many ...
Chris Johns's user avatar
  • 15.2k
3 votes

What determines the maximum possible slope of rail transportation (without rack)?

The actual maximum attainable slope is determined by the weight of the locomotive, the total weight of the train, the rolling friction of the carriages, and the kinetic(sliding) friction between two ...
Bart's user avatar
  • 1,184
3 votes

Is the assumption that "the passengers go to their destinations using minimal transfers" valid in an academic paper I'm reading?

The assumption for that paper is clear. In reality some people may or may not use a minimum transfer route as they might need to do some shopping on the way to work or home for example. That does ...
Solar Mike's user avatar
  • 15.9k
3 votes

Speed breaker design

Several companies have developed speed bumps / speed breakers that "disappear" when driven over below a set speed. My favourite designs are those that use non-Newtonian fluids. See this ...
Transistor's user avatar
  • 10.9k
3 votes

How are ships stacked ontop of other ships?

These ships can be loaded/unloaded: from a dock Figure : Loading/unloading from a dock (source Youtube) but they also have they have the ability to submerge in order for their cargo to be loaded/...
NMech's user avatar
  • 24.4k
2 votes

Positioning system for skips

I could not find anything in an internet search either. A steel wedges like you show should work fine. The taller the wedges the easier it will be for the driver to position. The swinging will stop ...
ericnutsch's user avatar
  • 8,181
2 votes

What's the purpose of a 'burger' lane in a roundabout?

Another purpose of such a lane is to allow for vehicles that cannot navigate the roundabout to travel through. For example a tram's turning radius may not allow them to drive around the roundabout so ...
ratchet freak's user avatar
2 votes
Accepted

What's the purpose of a 'burger' lane in a roundabout?

There are several of these near where I live (in the UK) but I've never heard the term "burger lanes" before. We don't seem to have a name for them - they just are! They serve the same basic function ...
alephzero's user avatar
  • 12.5k

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