Driving around town this summer has turned into a mighty expensive proposition. Not even gastrick bypass can alleviate the hurt.

There couldn’t be a better time to get reacquainted with the old public transportation system. Don’t know your Brown line from your Blue line? We interrupt that train of thought to introduce you to Hopstop.com.

First launched in New York in 2004, Hopstop has finally made its way to the city that works. (Or, rather, the city that works slowly if you’re trying to get from Bucktown to Wrigleyville on a Saturday afternoon.) It’s a website that promises to ease your commuting pain.

Using mathematical algorithms, Hopstop calculates the best way to get from point A to point B. Just enter your transportation choice (el only, bus only, el/bus combo), how much you want to walk versus transfer, and the approximate time you are looking to head out. Then submit your picks, and, presto, it spits out your optimal route.

There’s no need to worry about planning ahead — you can get access from your computer, PDA, or other mobile device.

So once you’re on the go, you can stay that way.

Available online at hopstop.com.