Jul 31, 2009

Accuracy of Google Maps Traffic Reports

Recently, while driving back from Pennsylvania, we ran into some traffic on a highway. On a whim, I decided to take a look at what Google Maps had to say about it. Using the Google Maps mobile application for my Blackberry, I brought up the Traffic overlay.

Surprisingly enough, Google was providing traffic overlays far outside of the DC metro area. So, that got me thinking - how are they so 'real-time' with this. And yes, they were pretty accurate about the traffic situation that we were in.

Did some research today, and it looks like originally they were getting this data from a number of sources, including road sensors, commercial trucks using GPS, commercial car fleets using GPS which they were able to aggregate to see how traffic was flowing.

My guess, during my drive, was that they are probably tapping into thousands of cell phones for this information - not tapping into the phones, but at least following where the phones are. Google Latitude uses this technology of cell-tower triangulation to give you your own position to some degree of accuracy. So, it seems it would be easy enough to take that data and use it to get an idea of traffic flow - lot more cell phones out there as compared with commercial vehicles with GPS.

I saw this link, which validates my theory. Looks like Verizon is providing anonymized data to allow for more accurate calculations of traffic flow.

What do you think about this? I think it is ok, but it would be interesting to see what others think...


  1. I have used this feature and have found it sometimes frustrating the lack of accuracy for the traffic information. I have been approaching the Throgsneck and White Stone bridges and determiend one or the other (as an experiment for the accuracy) and where Google Maps reported "NO TRAFFIC" there way traffic. OK, so perhaps it was because of the bottleneck off/on the ramps to the bridge. So I then I began looking at the Google Map traffic when I wasn't in traffic (ie further beyond the tollbooths / i95) and here I am in traffic and no traffic on the Google Maps and vice-versa. OK, I don't need Orwellian technology in my car etc but the accuracy is flawed on this.

  2. Yeah been finding that out in NY as well. I double check it against 1010 Wins traffic and while on days of very heavy traffic it looks right a lot of times it's just off in it's estimation.

    Like looking at it now you'd think the Holland and Lincoln tunnels were a nightmare and the city itself was a disaster.

    1010 reports no delays at either and nothing bad in the city.

    I check every night and this is the case more often than not.

  3. On Rt 6, Truro, MA (outer Cape Cod), Google Maps traffic info is completely unreliable. During summer I can see the long line of bumper to bumper stalled traffic on Rt. 6, but when I check Google, it shows only green. Closer to the Cape Cod Canal, however, G. Maps is much more reliable; when Google shows red you can start planning your detour, something I have been forced to do numerous times.