18 April 2013

Traffic Synchronization

Interesting article in the NYT the other day:  To Fight Gridlock, Los Angeles Synchronizes Every Red Light:

Now, in the latest ambitious and costly assault on gridlock, Los Angeles has synchronized every one of its 4,500 traffic signals across 469 square miles — the first major metropolis in the world to do so, officials said — raising the almost fantastical prospect, in theory, of driving Western Avenue from the Hollywood Hills to the San Pedro waterfront without stopping once.

The system uses magnetic sensors in the road that measure the flow of traffic, hundreds of cameras and a centralized computer system that makes constant adjustments to keep cars moving as smoothly as possible. The city’s Transportation Department says the average speed of traffic across the city is 16 percent faster under the system, with delays at major intersections down 12 percent. 

Without synchronization, it takes an average of 20 minutes to drive five miles on Los Angeles streets; with synchronization, it has fallen to 17.2 minutes, the city says. And the average speed on the city’s streets is now 17.3 miles per hour, up from 15 m.p.h. without synchronized lights.

I used to work for a startup that came up with a product very similar to what is described here, except that this product was a computer networking system.  We handled various Ethernet and T1 interfaces, and, the special-sauce behind our product was that our product synchronized network traffic that required Quality of Service (QoS).  I was the architect of the signaling protocol that facilitated all of this (and I contributed in many other ways too).

This was an interesting system.  Parts of the system used a hard-real-time OS, parts of the system involved a {thing} that looked a lot like an enterprise-class softswitch.  Not a day went by at this job in which I wasn't working on some interesting problem.

Our system worked really well too:  we could turn the jitter buffers essentially "off" in the various video/audio codecs that were on the endpoints that we used, and we could see very clearly that our system never dropped any packets.....even at nearly 100% load and wire-speed.

Unfortunately, we were a little bit before our time, and the market for this sort-of "near-perfect QoS" gear never really took off.

Still, when somebody like Bob Metcalf strolls through your company's lab and says that the technology that you've been working on is "really, really cool", that makes for a good memory.

There is never a dull moment in high-tech.

No comments: