h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

As you can probably tell by the title, I've been thinking about Cable Modems a lot. Over here in the UK, we are slowly but surely rolling out
Cable Modems to users, but just how do thay work?
Well, the principle is quite simple. The Cable Modem uses all the spare bandwidth on the Cable TV system to
transmit data to people. There is a problem with this, however. 30Mb/s
is the quoted speed, but this is for the line as a whole. Great if you're
the only person using it, but the line itself (Like your Cable TV Line)
Is shared along the whole street. If you're the only person in your street
to have a Cable Modem, enjoy the 30Mb/s downloads! If not, enjoy a fraction
of that. Anything down to 3Kb/s (33.6 modem speed). So, is it really worth it?
As I said, you need to (Covertly) observe how many people down your
street are on Cable TV, and how many use the Internet.
You could even spread malicious rumours about cable modems to
try and get the line to yourself, not that I condone this at all.
In the end, Cable modems are good if there aren't many people using them.
If there are several people using them, however, the speed goes down and it becomes
infeasable.