Forbes published my new map of Chinese overseas investments last night, and I’ve been pleased with its reception so far. It’s the first map I’ve made that involves animation, and it’s also the first map that I’ve built from scratch using nothing but ActionScript and Python. That turned out to be tricky in a neat, hackerish sort of way.

In the past, I’ve made all of my interactive maps using Avenza’s excellent MAPublisher software. MAPublisher handles geocoding and projections, which leaves me free to faff about with color schemes and callouts.

When you code your own map from scratch like this, though, you have to write something to geocode points and then project them (unless you’re partial to maps where Canada, Greenland and Russia seem to be taking over the world). There are less math-intensive solutions to this, like creating a map in Illustrator and then moving it to Flash (recommended for choropleth maps), but I wanted maximum programmatic control over the map (and the thrill of coding my own solution).

Geocoding was fairly easy in this case; I just derived centroids for each country using ArcGIS and merged those coordinates into the dataset from Heritage’s Derek Scissors using Stata. The data for each country now included deal value, acquirer, target, target’s country, latitude, and longitude.

Now for the projection: simply sizing down the latitude and longitude coordinates linearly by enough to make them represent pixel locations would result in a so-called ‘unprojected’ map that’s a dishonest representation of shapes and relative sizes. Unprojected maps also tend to waste a great deal of space by making the highest and lowest latitudes enormous and the middle latitudes small–a general problem for Web layouts like ours, where maps can’t be more than 768 pixels wide, and for this map specifically, because a great deal of Chinese investment has taken place in parts of Africa and South Asia that are near the equator. READ MORE >

We’ve just published a neat set of maps on Forbes.com that highlight America’s worst traffic chokepoints. The situation in New York, illustrated at left, should be familiar to anyone unfortunate enough to own a car in the area. The Cross Bronx Expressway, one of the great urban planning disasters of the late 20th century (and the subject of some really excellent exposition in The Power Broker by Robert Caro), has the worst single traffic tie-up in the country, as well as several others among the top 10.

The data that the maps are based on come from my friends at Inrix, a clever company based just outside of Seattle that measures traffic congestion using data from GPS tracking systems in commercial fleets. I’ve written about them before, and used their data in December 2008 to form the Forbes “Chirp Index,” a group of leading indicators with which we (fairly accurately) predicted that the recession would bottom out late in the summer of 2009.

After a couple of years of declining traffic congestion (due first to rising gas prices and then to rising unemployment), traffic congestion seems to be coming back. Growth in economic activity and stimulus-related road construction projects are bringing more people onto the roads and then slowing them down.

A minor tiff erupted in the comments section of my article; one commenter suggested that traffic congestion wouldn’t come back if only we invested more in public transportation. The next commenter wrote that public transportation hasn’t been proven to have any meaningful impact on traffic congestion.

Both commenters make legitimate, though incomplete, points. Public transit advocates tend not to talk of payoffs from transit investment in terms of immediate relief from congestion; after all, much of the housing and commercial space that’s been built in this country over the last 50 years is fundamentally incompatible with efficient transit schemes. The office-park worker who lives on a cul-de-sac will likely never be able to use even the most ambitious new transit system to commute–at least not as long as he lives in a housing tract and works in an office park.

That’s why transit advocates concede that new rail lines won’t immediately cut traffic on adjacent arterial roads. Rather, they say, transit systems encourage the kind of development that is compatible with transit use: walkable neighborhoods with a combination of townhouses, apartment high-rises, offices and shopping that are based around transit stations.

This kind of development is popular in places like Northern Virginia, where a well-run rail system links outlying areas to a massive job center in Washington, D.C. It takes much more patience to introduce these kinds of transit-oriented neighborhoods to cities with comparatively weak central business districts, like Phoenix, Los Angeles, and Atlanta, since people who live in them but don’t work in them may still have to drive to otherwise-inaccessible office parks.

So new transit networks in car-oriented areas constitute major investments in reorienting urban development over a period of decades, not a quick attempt to remove a few cars from highways. Traffic will come back this year–there’s no way around that–but sound investments now could mean that it will bring fewer headaches fifty years from now.