A complete map

Posted by Minh Nguyen on 8/24/2015

I saved my 10,000th changeset yesterday, as part of a months-long surveying and mapping spree in San José, California, where I currently live.

I never intended to map the Bay Area. Instead, I typically spend my free time helping to map my hometown of Cincinnati and tame TIGER deserts elsewhere in Ohio from the comfort of my (armless) chair. I always assumed that the middle of Silicon Valley would be full of tech enthusiasts who occupy their time by micromapping every last bench and bush. The map sure looked complete, with lots of highway=primarys and highway=secondarys, landuse areas covering every square inch, and plenty of rail and bike infrastructure.

But then, in April, I zoomed in. I had recently joined Mapbox to work on iOS map software, and the Show My Location function went right to my unmapped doorstep. Around me was an endless parade of outdated street configurations, missing landmarks, test edits, proposed BART stations tagged as the real thing, and GNIS-imported hospitals that had been closed for years. Most of the map hadn’t been touched in six years. In terms of POIs like shops and restaurants, central San José in 2015 was as blank as Cincinnati was in 2008. (San José is the country’s tenth-largest city, with a population 3½ times that of Cincinnati.)

before
Zoom in all the way to the spot marked San José, and this is what you would’ve found earlier this year.

As I added in pent-up local knowledge, I couldn’t help but notice some unfortunate tagging practices. The Bay Area is (ahem) liberal in its use of highway=primary and highway=secondary. It wasn’t difficult to find quiet residential roads with speed bumps, Child at Play signs, or unsignalized crosswalks being tagged as secondary, the same tag often used for heavily-used roads in other cities or 55 mph state highways in rural areas.

Most of the giant landuse areas that blanket the city need to be redrawn. Many landuse=residential areas conflate distinct neighborhoods or include tree-lined business districts (which look like residential areas from the air). Meanwhile, many industrial areas are being converted into residential areas due to a local housing boom. As much as possible, I’m replacing these generic landuse areas with more specific ones that correspond to individually named subdivisions, office parks, and retail complexes.


A typical landuse=residential area in San José spans multiple highway=primary roads. Either these aren’t really primary roads or this isn’t really one coherent residential area.

I suspect that the highway classifications and generic landuse areas, combined with decent rail data, made the map look a lot more complete than it really was. To a newcomer, the total absence of restaurants, buildings, and non-armchair-mappable information might’ve looked like a limitation of the project rather than a blank slate waiting to be edited. And again, there should be no shortage of visitors from San José, because this is Silicon Valley, where people talk about things like OSM. I’m sure the original mappers were doing their best at the time; unfortunately, six years ago, none of us knew as much about mapping ago as we do now.

San José is looking a lot better after an intense few months of surveying. There are plenty of POIs downtown – too many to fit onto the map at z19, in fact – as well as invisible attributes like speed, weight, height, and turn restrictions. I’m having particular fun mapping the many ethnic enclaves around town, which are very poorly represented on commercial map services.

caribees
This popular ethnic strip mall is now fully mapped in OSM (seen here in iD at z20). Apple and Google make a mess of things.

dgsmetoc
The San José place=city POI incorrectly sat 12 blocks away from where it should’ve been, at the site of this church, which incidentally is missing from Apple, Google, and HERE.


Meanwhile, OSM now includes that church, as well as its full Amharic Ethiopian name. (Deciphering the Amharic signage was a challenge in itself.)

Still, that’s only one city. We’ve always known TIGER deserts are a problem, but are other cities similarly languishing after an initial burst of detail, flying under the radar because we all think they’re being taken care of? Maybe we can prevent that from happening in the future by making the map look only as complete as it really is.