If You Had A Twin, But Didn't Realise...
Family Life3 mins ago
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For more on marking an answer as the "Best Answer", please visit our FAQ.Hi sammd,
Does the line near you have overhead cables? If it has and the train has an overhead frame that is touching the cables then it is purely driven by electricity, no pollution..
Other trains are driven buy electricity but the have a diesel engine on board which produces the electricity to drive the train, it is this diesel engine which produces the fumes and also makes a throbbing sound.
Other noises you could be hearing are cooling fans for the electric motors.
There are basically two types of BR electric trains. Some run on an overhead supply and some run on a third rail system. The third rail system is predominantly used in the south and south east of the country, while the overhead system is more likely to be seen north of London.
Trains out of Paddington to the West Country are diesel.
I don't know how much pollution diesel trains give out, but it would be considerabl more than a large wagon.