Questions tagged [rail]

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28
votes
3answers
8k views

Why are railroad tank cars bent in the middle?

I recently noticed that the cylindrical shape of a railroad tank car is not completely straight but has a bend in the middle. The entire tank is a bit lower there. What's the reason for this bend? ...
1
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1answer
54 views

is this a picture of a plate girder train bridge or a deck truss train bridge?

Is this a picture of a plate girder train bridge or a deck truss train bridge?
1
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1answer
100 views

Why are trams always electrified with DC, while trains can be electrified either with AC or DC?

Trains can be electrified either with DC voltage or with AC voltage. Various networks across various countries uses various standards. My question is however for trams, which are basically a lighter ...
0
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0answers
52 views

Could railway overhead wires be used for long distance electricity transmission?

Most electrified railway in Europe operates at 15 kV 16.7 Hz AC or 25 kV 50 Hz AC. Power is typically produced between about 2.3 kV and 30 kV and stepped up to 115 kV to 765 kV AC for long distance ...
1
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0answers
22 views

Does westinghouse braking system prevent using anti-lock system?

This question concerns the Westinghouse braking system. If I understand correctly this video, in an emergency braking (e.g. in case of failure in main air pressure line) the pressure in the main ...
5
votes
2answers
212 views

Why railroad concrete tie tips become dry first after a rain?

I've witnessed this phenomenon: Why are only the tie tips dry? Why are only the stones around the tips dry? This is a railroad in Ukraine in the morning after a rain at night. Around 80% of observed ...
1
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1answer
89 views

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

I always wondered how the drivers of steam locomotives could observe the road.
2
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2answers
90 views

What is the purpose of this dead-end rail junction?

This rail junction is located on a steep, short, local railroad line from the "mainline" in Reno, NV to the community of Stead. The track is new/maintained and there is no evidence of an old siding. ...
3
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0answers
40 views

Do high speed trains use ventilation and filtration systems similar to aircraft?

This article discusses the ventilation and filtration in aircraft: Ventilation rates provide a total change of air 20 to 30 times per hour. Most modern aircraft have recirculation systems, which ...
5
votes
1answer
50 views

Why would a specfication for a motor require that overtemperature protection be realized by modeling heat generation and not with an embedded sensor?

I'm reading the procurement documents for the R211 railcar contract, which is for electric multiple unit subway cars designed for rapid transit applications in New York City. The railcar's propulsion ...
0
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1answer
159 views

Why are tank cars cylindrical?

Hold height constant. Then a Rectangular Prism, with length and width = radius of the cylinder, has greater volume! So why aren't tank wagons (railroad vehicles that transport gas and liquid) ...
1
vote
1answer
83 views

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

Trains where originally designed to keep the train on track. At the time trains where pulled by horses and used to transport coal (and such) out of mines. The two functions have very different ...
1
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1answer
72 views

How does dynamic braking work with railway locomotives?

General Electrics boasts that its Evolution series diesel-electric locomotives are capable of dynamic braking. Dynamic braking uses the electrical traction motors on the locomotive axles - motors are ...
34
votes
6answers
7k views

What is the purpose of these “partially filled in” locomotive wheels?

I recently visited a railway museum with a lot of Soviet-era locomotives. The picture below shows the wheels on a locomotive from the 1930s or 1940s. Some of the wheels are thicker on one side (as it ...
18
votes
7answers
12k views

What are the engineering principles for a train to get electricity from the railway

How many general methods are there for transferring electricity from the railway to a train? I could see that some trains are connected by a pantograph and some have a third rail. Are there any ...
2
votes
1answer
210 views

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

Last night while waiting for the train at South Yarra station in Melbourne, I saw these reflective triangles stuck on the sides of the train track rails. They were evenly spaced a few metres apart for ...
2
votes
2answers
320 views

Is there any reason why “inner-flange” style trains are almost universal?

There's basically two ways train wheels can operate, the flanges could be either "inner" or "outer". Switches can be made in equivalent ways for inner and outer flanges. We could expect that, just ...
1
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2answers
186 views

How do maglev trains turn given that they seem to have more than two bogies per car?

All of the images of maglev trains that I've seen seem to have a continuous drive mechanism along the entire length of each car: I assume this must be articulated some how, or the train wouldn't be ...
2
votes
0answers
66 views

What does “'LBLMY” mean on the side of a railcar?

In this photo, what does 'LBLMY signify? Seeing it directly under the capacity, and 5000 pounds lower, I'm guessing it's a "limited capacity" of some sort. But I ...
4
votes
1answer
114 views

Can a Foucault's current brake be used on the rails themselves to brake trains?

Your typical Foucault's current brakes operate on a disk, which is placed in an electromagnetic field in order to transform kinetic energy into heat without friction. The problem is that the disk ...
1
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1answer
107 views

What's this box in steam locomotives?

In the past few weeks I've seen several European steam locomotives in museums. I noticed several of them have a box in the driver's cabin, similar to the one in the picture I've attached. Several ...
1
vote
1answer
251 views

What are the factors that made narrow-gauge railways cheaper in the early 1900s, and are they still applicable today?

Back when railways were being massively build, in the 1900-1910 decade for example, most new lines were made with narrow gauge, instead of the standard gauge which is 1435mm for most of the world. ...
2
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0answers
68 views

Is there a particular reason the Moléson funicular is built as a giant bridge?

So I live in Switzerland and there is lots of funiculars in my country. Most of those were built between 1890 and 1930, and for most of those the line is on the ground most of the time, there is ...
4
votes
3answers
2k views

How do gapless rails deal with thermal expansion?

Gapless railroads have their joints welded together to reduce noise. The lack of a gap between rail sections also reduces wear on both the track and the wheels. However, because the weld essentially ...
0
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3answers
1k views

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

(Disclaimer: To make things clear I'm talking about adhesion railways and excluding rack railways as those are an entirely different technology and requires specially equipped vehicles. Also I'm ...
1
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0answers
35 views

Specific Questions about Traffic Signal Preemption at Grade Crossings

Several questions, regarding traffic signal preemption at a grade crossing Is the preempt relay, which triggers the preemption sequence, located inside the bungalow which houses the grade crossing ...
1
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0answers
114 views

How to define the Clothoid Constant in Clothodial Arc ( Spiral Curve)?

Referring to the document here on IfcClothoidalArcSegment2D, we have ClothoidConstant, which is defined as The constant $A$ (not $A^2$), that determines the ...
1
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2answers
109 views

Sudden increase in noise levels - subway noise -happend overnight [closed]

This is real life issue I am having currently and I am puzzled as to why it happened. I have lived over the subway lines (two actually each going in the opposite direction, two sets of tracks) for ...
1
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0answers
102 views

Cone shaped train wheels

I was watching this Feynman video and (as usual) his explanations make a lot of sense. Now I just took a train, and am not so sure anymore. Looking at the train wheels they did not appear cone ...
-1
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1answer
57 views

Why is there a delay with railroad signals? [closed]

Ok so. When you look in videos(or in real life) with the railroad signals, when a train passes over it, it takes around 3 to 5 seconds for it to actually change to the correct aspect. What is up with ...
3
votes
4answers
463 views

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

Looking at the capacity of train networks, systems like CBTC help increase capacity, but the spacing of trains is ultimately limited by poor braking performance. In my understanding, safe distances ...
1
vote
1answer
53 views

Mechanical Engineering- Modeling contact in Abaqus

I have simulated a 2D model in Abaqus which indicates 2 main part, first a sector that represent as wheel and, second a rectangular that represent rail. the wheel and rail are in contact and wheel ...
3
votes
1answer
162 views

How can traffic signal controllers handle multiple conflicting preemption requests of equal priority without dropping one?

Let us assume that we are North American traffic engineers, and have the (hypothetical, plausible, yet pathological) intersection configuration depicted (not to scale and lacking lane lines, sorry -- ...
6
votes
1answer
310 views

Monorails - why even have them?

My (highly limited) engineering intuition says: Dual railing is good - for balance, for switching of tracks, for lightening load and making sure it is applied in basically the same direction always, ...
7
votes
7answers
6k views

Why do electric trains arc at high speeds?

When I watch videos of high speed trains I always see explosions of electricity near the top, or arcing. Why does that happen? I know that the Acela does it a lot but other high speed trains have it, ...
2
votes
1answer
150 views

Balancing Locomotive Power

My first post here. I'm curious about how power is balanced in multiple diesel-electric locomotives. I understand to that two locos can be ganged in terms of controls, to set speed etc, so that one ...
2
votes
4answers
895 views

Why do train cars have unevenly spaced axles?

Every train car I can remember has its axles arranged like the photo. Two are put very close together in one chassey, and two more the same way at the other end. But why do that? If you want 4 axles, ...
4
votes
1answer
293 views

Why are rail signals overbuilt compared to road signals?

Here is a photo of a railroad crossing near a road intersection. Traffic, Rail Lights out of Sync at Fruitvale Avenue Crossing The road signals are mounted to slender poles (or even suspended from a ...
2
votes
1answer
95 views

What is this indicator called?

None of my fellow commuters know what this white panel with, what appears to be a red slider attached, is called and what it is for. This particular one is on a platform edge which happens to be over ...
1
vote
1answer
117 views

Does the decrease in speed of the train at the curvature changes the properties of Speed Time Curve Of Urban Service

Ok, I wish to plot the speed time curve of the my urban service . The travel includes the curvature ( as shown in image ( just for reference )). The train speed is decreased while it runs along the ...
7
votes
2answers
2k views

Why do some high speed trains have long noses, while others do not?

Why do some high speed trains like the Shinkansen E5 and E6, have really long noses while other trains, like the Eurostar and Javelin, have shorter noses? How does the shape of the nose affect the ...
3
votes
2answers
886 views

Why use rectifier / inverter in locomotives?

Image Source Why not just take the AC from the alternator to the motors? Why go AC to DC to AC again?
6
votes
3answers
2k views

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

Why does the ballast of train track need good drainage? I read something about preventing "fouling" of the ballast, but don't know what that means or why it would be structurally bad. Could ...
3
votes
1answer
412 views

Why do all high-speed trains run on electric track (as opposed to normal track with diesel-electric trains)?

AFAIK, all high speed trains (200+ kmh) run on electric track. Why is this? Is there something about a diesel-electric engine that makes high-speed trains more difficult? Here's some other data, and ...
2
votes
3answers
433 views

Two railway locomotives connected one after another

I am relatively new (not in terms of registration but in terms of activity) on this site. I don't know if this question is suited here. I have seen two rail locomotives connected one after another ...
3
votes
2answers
442 views

Train Signalling - What Do They Mean

I'm asking this here because I really cannot find a better place to ask this. Near my house (in the US), there is a pair of parallel train tracks operated by Union Pacific, primarily for cargo-...
2
votes
2answers
133 views

Historically, how did tram switches work?

Historically, the switches on regular railways were switched manually using a lever by dedicated staff to route trains correctly before getting replaced by an automatic electronic system. A similar ...
20
votes
7answers
8k views

Why would a train automatically derail if a signal is passed at danger?

In a recent incident in London Network Rail said an empty train had travelled past a red signal, which resulted in an automatic derailment. No one was injured. [link] The derailment has caused ...
3
votes
2answers
250 views

How to notate the position of a train?

How is the position of a train modeled in a computer control system? I can think of two basic approaches but I am not sure which (if any) are used in the real world. Lat, Long Ex: (-42, 23) The ...
6
votes
2answers
351 views

On a Diesel/hydraulic DMU train what exactly does the “go faster” lever control?

Let's say that you are driving a Diesel Multiple Unit† with either mechanical* (i.e. an actual gearbox with multiple ratios) or hydraulic (i.e. two or more torque converters) transmission. When you ...