Jun 112008

I’ve recently been monkeying around with bike maps, and trying to import them into Google Maps.

Here in Madison, bicycling is very popular. The local cities and Dane County have been very helpful in creating some maps for bicyclists. But their maps are standalone, and can be cumbersome when trying to figure out a bike-friendly route across town.

On the other hand, Google Maps is useful, flexible, and extensible. It would be great to combine the two.

Luckily, there is an intersection. The bike maps are also available in KML format, which is what Google Earth (and Google Maps) can read and import. (You can import them into Google Maps by going to “My Maps“, clicking “Create New Map”, then clicking “Import”, and selecting the KML file from your computer or with a web URL.)

Not so luckily, the Madison bike maps are available in a few HUGE KML files with everything and the kitchen sink all in those files. When I tried to import an entire KML file into Google Maps, it kind of worked, but became unusably sluggish. So, what to do?

Well, KML files are a type of XML file, which means that they’re text files, and as such are hand-editable. You can change the wording, delete parts that you don’t care about, and slice the good stuff into manageable chunks (like, say, one bike path per file, or a handful of small bike paths per file).

It turns out that the chunks are quite digestible by Google Maps. And once you’ve imported them, you can do all the usual tricks to them (annotate them with descriptions, pictures, and waypoints; change the line color and size; add more segments by hand; etc.).

Plus, having all the individual bike paths as separate maps is kind of handy, in that you can turn them on and off individually when you’re figuring out your biking routes.

Here are some results of importing Madison bike maps into Google Maps.

There are a few problems, though. First, there’s no way in Google Maps to make a “group” of maps. So, if you want to add the Capital City Trail and the Southwest Commuter Trail to “My Maps”, you need to add each of them individually. It would be really nice to be able to create a group of all the bike maps for Dane County, for instance, and to be able to view all of them at once without needing to add and then click on each one individually.

Second, there’s currently no way in Google Maps to do much of anything with the bike maps besides look at them. You can’t use them to “build” a route–to tell Google Maps to follow them when computing the best way between two addresses.

Third, at least for Madison, Google Maps currently has a serious misregistration between the map data (streets, highways, and any maps you create from correct lat/long data) and the satellite view–the maps and the satellite views don’t line up. So, the imported KML bike trails don’t line up with the satellite view either, which makes viewing them a little frustrating. It also brings up the question: If you want to add to or edit the maps by hand, do you use the satellite view or the map view? There isn’t an obvious answer to this question. The satellite view will indeed show the physical traces of bike paths, and thus makes it very easy to trace them. But the map view has the correct lat/long information, so using it is in a sense more correct. Hopefully Google will fix the misregistration one of these days and make this issue go away.

Finally, if you do create a single map with lots of bike trails in it, they won’t all display at one time if there are more than 50 or so trails (or segments of trails) in your map; only the first 50 will show up–the first “page” of trails / segments in the “list”. You’ll need to go to the “next page” to have the trails that make up the next part of the “list” displayed.

Still and all, it is pretty remarkable that you can do stuff like this at all. And, knowing Google, the maps that we import today will quietly and suddenly become much more useful tomorrow.

 Posted by at 8:30 AM

  One Response to “Madison Bike Path / Trail Maps and Google”

  1. Thanks for your blog on our bike map! I’m pleased to see that you are putting the KML files to use. There are some exciting uses to explore with this technology.

Sorry, the comment form is closed at this time.