# Tag Info

48

Those are counterweights. They work exactly the same as those lead counterbalance weights on the wheels of your automobile. If they left those out, then those connecting rods and bearings would create an out-of-balance condition, and the wheels would vibrate at higher speeds. That could very well damage the wheels. But as a couple of others have nicely ...

32

The picture, below, of the exaggerated long section of the Channel Tunnel was taken from Wikipedia. Full-sized image here. Some of the limiting factors for the Channel Tunnel are: Railways don't like steep gradients The tunnels comprising the Channel Tunnel were excavated using tunnel boring machines (TBMs). Like railways, they cannot tolerate steep ...

29

Firstly, the incident happened as the train was leaving a siding passing a shunt signal. These provide less authorisation than a normal signal does, even when they are not at danger (the train can permit as far as the line is clear or the next signal, there is no guarantee the track ahead is clear). Now, in the UK, there are four train protection systems: ...

28

Those are balance weights against the joints used for the rods linking the wheels together.

21

There are a few main reasons why suspension bridges aren't used for railroads. The main reason is that suspension bridges are typically used where very long spans are needed. Trains are very heavy, especially when compared to lanes of highway traffic. This means that long spans require very strong support structures, which in the case of suspension bridges ...

20

While I'm sure it caused less damage than a train collision Exactly. This is a last-resort response intended to avoid a full-on collision. A derailed train causes some damage and is a mess to clean up. A collision between two trains will likely cause much more damage, be even harder to clean up, and quite likely get people killed. It can also impact the ...

19

Train Brakes The common brakes on trains are air brakes. As the name implies, these work off of air pressure. The braking power isn't controlled in the way that you would immediately think of though. They do not work like car brakes where the harder you press on the brake pedal, the harder the pressure goes through the lines to the brake cylinders. They ...

19

Pantograph and third rail are pretty much it. Engineering principles: both have a conducting surface on the train (moving) in contact with the stationary rail/wire, in both cases you need a material that's resilient and conductive. The contact strip is a wear material. Differences: overhead catenary wires are flexible and will move around when a train ...

18

Several factors influence this: at high speed, there's a higher chance of the pantograph losing contact with the catenary wire: at higher speed, bumps in the wire cause a more violent excursion that can exceed the capability of the suspension of the pantograph. Low-speed trains can show arcing too. high-speed trains often use high voltage (15 or 25 kV), ...

15

The oversized counterweights on the second set of wheels are to help balance the additional inertia of the pistons, piston rods and crossheads, which are directly connected to the wheels on this axle. (In a former life I was a museum conservator and rebuilt, and operated, steam traction engines and a locomotive.) ronford

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

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 ...

13

Possibly the reputation of railway suspension bridges was fatally damaged by the poor performance of the very first one? In 1830, the Stockton and Darlington Railway built a suspension bridge over the River Tees, designed by Samuel Brown. (Illustration by William Miller, from The North Eastern Railway by William Tomlinson, 1915.) Intended to carry trains ...

12

I won't say it's not possible to make a noticeable difference. But I would say that it's pretty darn unlikely. The lift and drag forces on any body generally depend on the velocity of the body ($v$), the density of the fluid ($\rho$), the area of the object ($A$) and a dimensionless coefficient ($C_L$ or $C_D$). The applicable area can be a bit fuzzy in ...

12

Spiral A spiral curve is a geometric feature that can be added on to a regular circular curve. The spiral provides a gradual transition from moving in a straight line to moving in a curve around a point (or vise-verse). The use of a spiral is about making the road or track follow the same form that the vehicle naturally takes. In a car, you don't go ...

11

Why derail? If the train went past a red signal, then all of the other safety systems already failed! The method of last resort is to make absolutely sure that the train will not travel down the track. That is done by derailing it. How did it get to this point? The real question is how did it get to the point of passing a red signal? At that point, ...

10

Is it indeed possible Yes and reasonable to craft a carriage side of such large single sheet It can be reasonable, but typically isn't. To form an entire side of the carriage from one sheet of steel would require a forming press that is gargantuan. However, one could instead have three more reasonably sized presses and then weld the sections together. ...

9

It isn't a question of being "aesthetically pleasing to the eye", but rather of comfort. If you had a curve that was simply a circular arc, upon entering that curve, you would immediately feel a sideways centripedtal force that is proportional to your speed and inversely proportional to the radius of the curve. In other words, you would have to suddenly ...

9

You don't want to decrease the downward force on the wheels because that is your primary means of slowing down in an emergency. It already takes a while to stop a train, don't make it any longer. Remember that kinetic friction (wheels locked) is proportional to the downwards force on the wheel and the brakes are spread along to each car. Train wheels have ...

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 ...

9

It all depends on the level of efficiency you seek. A train, given its size, has a ridiculously small cross section. This small frontal area footprint is being 'pushed' by the inertia of hundreds of tonnes of metal. All high speed train have aerodynamic noses, but some will tend to be pedantic about how many thousandths of a percent efficiency they can ...

9

It is due to the high voltage still causing a connection when the contacts separate due to an irregularity (bump etc) between the contact and the wire.

9

In terms of safety for the public at large, an overhead cable & pantograph would be used outside in the open so as to prevent anyone, or any forms of wildlife or suburban pets or farm animals from inadvertently being electrocuted by coming into contact with a third rail at ground level. Where a third rail system is used on the Earth's surface a ...

8

Light rail, and a floating rather than a suspension bridge, however I suspect many of the issues are the same: http://bulletin.pbworld.com/volumes/2014_04/taking_light_rail_over_floating_bridge.aspx "The bridge destined to host light rail is the Homer M. Hadley Memorial Bridge, one of the longest floating bridges in the world, which currently carries the ...

8

The tracks are preheated and welded at a calculated temperature (that depends on the local weather) at the time of installation. When the track cools to the ambient temperature, this leaves a tensile stress in them. This tensile stress increases on colder days, and decreases on hotter days. As long as the stress remains tensile there is no warping. On ...

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

It's possible, aluminum sheeting comes in large rolls; You take one that is wide enough and you can cut out a single sheet long enough for the length of the carriage. It's probably attached to the structure using welds on the inside However seams can be very well hidden under the paint after welding them together and sanding it down.

7

Short answer: I suspect that ripping out the speed control lever would have immediately applied the emergency brake. In every safety system I have ever designed, emergency stop buttons are normally closed switches so that nothing will operate unless the switch conducts current. Therefore if the wires to the emergency stop were severed, the brakes would ...

7

"standard EM interaction range" depends a lot on frequency, or its inverse which is wavelength. Your 25 kV catenary probably is 50 Hz or 60 Hz, same as your national grid. That means the wavelength is 6000 kilometers. That's far more than your dimensions. Hence, you can ignore the electro-magnetic aspects and treat this as an electro-static problem. Arcing ...

7

Diesel locomotives can't deliver enough power. The power rating of the diesel generator on most locomotives ranges from 2 to 4 megawatts. The combined power rating of motors on high-speed trainsets range from 5 to 20 megawatts, depending on size and design speed. Diesel engines are rated for maximum power, while motors are rated for continuous power. Motors ...

Only top voted, non community-wiki answers of a minimum length are eligible