distance-comparator is helping to compare distances between cities by using a known city as a reference.
I have a problem understanding distances just by a value. For example, how far is 200 kilometers? Well, it is pretty far, you won't be able to get there by car in an hour but you should be there in 3 hours. The trick is that for me it's not saying much as I don't know how to apply this fact.
I prefer to handle distances in some context, when I can compare them between each other and especially when I can compare them with some known distance. For example, I know that you can go from Prague to Dresden, spend there a whole day and return back the same day. Comparing this with Kyiv I see that distance from Prague to Dresden is roughly the same as from Kyiv to Chernihiv. And I understand that one-day trip makes total sense. Or I can tell Bastei is pretty close to Dresden, it is closer than Boryspil' to Kyiv.
To run distance-comparator locally I just run
python -m SimpleHTTPServer 8008
from the root project directory and go to http://localhost:8008 in browser.
To run automatic tests I go to http://localhost:8008/test/ in browser.