18

If I'm understanding your question correctly, you're asking why a flyover has excess clearance beneath it for traffic below. For example, if the tallest vehicle expected beneath the flyover is 12ft tall, the flyover may have 14ft clearance. There are many reasons for this, some of them more obvious than others. You don't want to try to squeeze a 12ft tall ...


14

This is an admittedly North American response. MGT In the US, how much traffic goes over a given track in a year is measured in Million Gross Tons (MGT) e.g. 1 MGT = 2 000 000 000 lbs [spaces instead of commas to be world-friendly]. This is a measure of the total weight of cargo and vehicles but not necessarily the number of individual trains. Rail Life ...


13

Do you mean, for example, a bus entry door? It may be as simple as the "service factor" for motors ("electromagnetic devices") as compared to pneumatics. Inexpensive motors with sintered bronze bushings wear out, and better ones with actual bearings must be routinely lubricated. Air-operated cylinders are cheap and last a very long time, with the air ...


13

Precipitation Snow Snow can be a problem for running trains, but it really doesn't affect the rail/ballast. Just like on highways, the snow needs to be moved away, but it doesn't have many other effects. Trains are used to plow through small amounts (Wikipedia): and large amounts (Wikipedia): Ice Ice could cause more of an issue due to adding thickness to ...


9

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 track structure. Why is this necessary? Well, there are are two main underlying reasons why you don't want water in your track structure: It tends to lead to ...


7

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 highway locations -- milepost + track name, and named locations called "stations" in US railroad parlance. The former are not far off in usage from their highway ...


7

This information comes from a design document by the Iowa DOT (US). It might not apply everywhere in the world, but the considerations are probably universal. For clarity, the amount of banking of a turn is typically called super elevation. At least in the US, this is given as a percentage for roadways. The maximum super elevation is 8%. The typical high-...


7

They are smoother and if something gets caught in between them then the maximum force it can exert is capped depending on the pressure and the piston area. This means that a trapped limb is less likely to get crushed. In an emergency (a typical concern for public transport) you only need to open a valve (pulling the emergency open will do that) and push to ...


6

The air used for the air cushions will come from the air still in the tube pressurized by the pod itself. Thus the system remains closed (all air that is released is sucked out of the environment).


6

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 former has to carry around a lot of stuff at takeoff. The only possible way to save you from the fundamental issue above is to throw the stuff out the back so ...


6

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 reorient the crash to be parallel to the barrier by lifting the front tyres to reduce friction between the tyres and asphalt in order to assist the redirection. ...


6

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 the lines are on the Earth's surface how much land will they occupy and could the land be better used for something else? If the lines are underground, or ...


6

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 split up all the trains to hit every destination, you end up with only a few trains a day going where you want to go. Since you don't want to travel then, you ...


5

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, essentially, comparing a garbage truck to a car is pointless: the car may as well not be there. In other words: the car is so insignificant compared to a garbage ...


5

The easy question Do any of the components above have higher costs to society than CO2 per same unit of measure (e.g. gram, kilogram, or ton)? Yes, absolutely. This should come as no surprise given the composition of the exhaust—it's mostly inert gases. Water vapor, CO2 and nitrogen gas are all products of the various reactions taking place in the vehicle'...


5

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 railway is immense). A single narrow line will exert less torque on the pylons than a broad dual rail would. Monorail is strictly for passenger transport, so ...


5

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, I'm not sure which). This is because if the axle is offset, the wheel that's to the outside has a larger diameter, and tends to drive the axle to turn toward ...


5

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 than sufficient for all but really steep slopes (>10% ). Train engines may be limited in both torque and power when it comes to moving a heavy train up a steep ...


5

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 an unintended benefit: because of change in the subtended angle from the driver's eye to the bumper, they signal the distance better by changing the ...


4

Speaking personally (I work for a US Class I as a software developer, working with a system that will interface closely with the PTC implementation at my company and knowing developers who have worked on parts of that PTC implementation): The main physical hardware improvements required to implement AAR-type PTC on a rail system are fourfold: a. The ...


4

In the United States the public safety standards, designed by the American Association of State Highway and Transportation Officers (AASHTO), require that: Vertical clearance on State trunk highways and interstate systems in rural areas shall be at least 16 feet over the entire roadway width, to which an allowance should be added for resurfacing. On State ...


4

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 and off. A both liquid rockets and and jets need fuel but a rocket engine also needs oxygen, the jet engine pulls this from the air. So for the same amount of ...


4

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 ballast if it has good drainage. The idea with unballasted track is that the concrete redirects the water so that the ground immediately below it stays dry, ...


4

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 risk causing a derailment. Excessive braking at the rear also risks derailment if on any sort of curve. This would seem to preclude any "simple minded" ...


4

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.g. on the platforms) to create an accurate 3D picture of any movement of the track. For example the sleepers or ballast may have been replaced recently, or ...


4

The English term for this is definitely crate.


4

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 asphyxiation problems on some mountain routes where there were multiple tunnels and snow sheds. The downsides to the design were concerns about what would happen ...


3

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 values of the drive.so to get a rated values accordingly to drive AC-DC-AC converter are used.


3

For a given method of transport to become the most popular, it needs to be the safest, cheapest, most efficient way to get from point A to point B, relative to comparable forms of transportation. In this case, the comparable transportation method is to use normal trains, which run on coal, electricity, etc. Let's compare the two: Safety This is sort of ...


3

Like many things, the driver is an economic one. Maglev is an entirely practical proposition but must compete in cost-benefit with other systems - notably wheeled ones. It generally fails to do so. About 15+ years ago China investigated various means of providing high speed rail services. A "demonstration" Maglev system was constructed between Shanghai's ...


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