Painting the Traffic Picture
Traffic is being drawn in more places every day. From Google Maps to your local TV news, from GPS devices, to iPhone apps– everyone wants traffic information. Now I love data, stats, figures, and charts as much as the next guy but trying to interpret traffic data is almost as frustrating as traffic itself. Here is my open call to the industry to clear the lane of confusion, my suggestion on how to depict traffic so that drivers can get meaningful and actionable data from the pretty traffic maps.
The Standard Traffic Map
Consider this map– a fairly standard depiction of “live” traffic in the Boston area from Google Maps.
Does anybody actually understand what those colors mean in a way that gives you actionable information? Sure, black/red = pretty much stopped. Red = slow. Orange = not perfect. Green = fast. That’s nearly what the legend tells us. But I still don’t know what that means.
To me, it appears that most of the highways are green. I’d expect them to be “fast” (green). And most of them are. Most of the smallest surface streets are red. Most of those roads have a 25mph speed limit and have lots of traffic lights so I’d expect them to be slow. In a glance, the colored traffic information doesn’t show me any more information than I could have deduced from the road classifications themselves. Big fat orange line = fast. Yellow line = not perfect. White = moving slow. Grey thin line = crawl.
In other words, I can make a pretty good estimation of how fast cars will be moving just by the road classification– I don’t need a “traffic” map to tell me that. You almost never see “green” paint on the smallest roads, yet they are very frequently in red. The more secondary roads that start to get covered by traffic data, the stranger this will look, especially to those familiar with the area.
A Matter of Perspective
Not surprisingly, people look at traffic from different perspectives based upon where they live and were on the map they are looking. To someone who lives in Los Angeles, drawing a red line on the 405 at 5:00pm is simply confirming that a bear does in fact poop in the woods. There is no information there. To a tourist not familiar with the area that happens to be driving through, the red line is important.
So there are two very distinct categories of people who are seeking traffic data.
- Commuters, who know and understand what normal traffic volumes are. These people don’t really care how fast or slow traffic is moving– they want to know how it differs from normal. They want to know if an accident on their typical route will cause them an out of the ordinary delay.
- Travelers have no benchmarks for how traffic typically is. So they are more concerned with how fast traffic is moving (normal or not) so they can make route judgements.
Bryan Mistele of INRIX recently said this to GPS Business News.
Painting colors on a traffic map is easy to do, however at the end of the day, accuracy of the traffic information itself is what really matters.
I agree with Bryan that it is the accuracy of the data that matters most. The problem is that the same painting of colors on a traffic map can mean different things to different types of drives. Legends presented on various websites, traffic maps, and GPS devices doesn’t describe what it is we are looking at. If a road has a speed estimate of 25 during low traffic and cars are moving at 25 mph, what color should that be? If I’m a commuter and know the road it should be green. If I’m just traveling through the area I could probably deduce the speed of the road simply from the road classification. Should it still be green? If the legend says red=slow then should it be red?
I took a way too small of sample size, highly unscientific poll of a few people recently. I showed them a traffic map and asked them “Does the red line mean that traffic is moving slow (at a set speed) or does the red line mean that traffic is moving slower than expected?” The results were about 50/50. The next question to me of course was “which is the right answer?”. To which sadly I… me… the GPS guy… had to say “I honestly have no idea.”.
So here is my proposition. Every traffic map should have two modes. the first mode is ‘Traveler’. In this mode traffic is color coded strictly on current flow data. Regardless of road classification, historical traffic data, or predicted traffic data– if vehicles are moving at set speed ranges, give them a particular color with a clearly defined legend.
A second mode should be called ‘Commuter’. Here, we really don’t care what the current speed/flow is. Simply display the traffic data according to how it differs from the predicted flow– either in comparison to road classification or (better) a historical traffic model. In this manner, green might mean that traffic is moving along at 90% or better of historical values for that road. If traffic is only moving at 50% of speeds for that day of week and that time color it red. And again– provide a clear legend so we know exactly what it is being presented.
The Marketing Challenge
So why don’t we see maps setup from this “commuter” perspective? My guess is that it comes down to the impressions it gives a customer. When debates come up over which traffic provider is “better” the discussion almost always ends up looking at which map has more colored roads. The pressure to paint more colors on more roads is appealing to the traffic providers as it makes them look like they have more coverage in more places. To some extent that is true, but painting a traffic picture on a map and delivering good, actionable data are not necessarily in sync.
Traffic has been a hot topic lately with people debating which traffic providers (INRIX, NAVTEQ Traffic, Clear Channel, TrafficCast, AirSage, etc) provide the best data. Pretty darn impossible to tell when we can’t figure out exactly what it is being painted in various maps. In most cases, as with the Google Maps example, the colors simply represent current speed. I can make guesses of speeds simply by looking at the colors for road classifications. I don’t need a “traffic” map to tell me that.
I know why the sky is blue, but I don’t always know why this road is red.