Hi,
I hope you’re fine. I’d like to ask you about something that gives me a constant headache. Which of the three sentences is OK?
1. I usually travel by Underground
2. I usually travel by the Underground
3. I usually travel on the Underground
In this case, it looks like you are using Underground as a proper noun – the name of the subway system in London, England. Because it refers to a specific subway system, it is best to use “the”.
You can actually use either “by” or “on” as the preposition here, so either sentence 2 or 3 are correct. The first sentence is not incorrect, though. You could say “I usually travel by Underground” and still be correct.
However, the best way to say this is none of the above. Most native speakers would use the verb take or go by for different forms of public transportation. It would sound a bit more fluid to say:
- I usually take the Underground.
- I usually go by the Underground.
