Token ring road traffic control and congestion management

Read an article the other day in Wired, A system to cut traffic that just might work, about two MIT students doing research to help Singapore better manage traffic congestion. They have come up with a sort of token ring network for traffic.

In their approach every car when it enters a “congestion zone” is suppplied an electronic token and when that car leaves the zone it retires it’s token (sound familiar). When the zone is too congested, no new tokens are handed out and cars are re-routed around the zone using GPS provided directions.

It seems a bit hokey but using tokens to control congestion is an old technology and works just fine. The problem with applying tokens to controlling road congestion is that it’s not so easy to re-route someone around a zone if you have to go into it for work or entertainment.

Traffic congestion management today

Most congestion management schemes use congestion toll pricing with transponder and radio transmitters/receivers at entry points into congestion zones. In this fashion metropolitan areas can raise and lower toll pricing on traffic that enters the zone as an incentive to reduce traffic. But this requires special purpose transponders in every car and radio towers at every entry and exit point which fixes the congestion zone boundaries and has a high initial fixed costs.

Singapore’s congestion approach is similar with transponders and radio readers at select entry and exit point locations around the city.

Traffic management via tokens

What the MIT researchers have done is to use a broader WiFi type of radio transmitter in their car transponders with a wider range and use cell tower-like receivers around a metro area to triangulate where a car is and when it’s in a congestion zone and to transfer this information to a central repository.

One advantage to the MIT solution is that the congestion zones are no longer fixed, but can become whatever boundary a city administrator wants to create on a map of the city. This way, different zones could be attempted as experiments whenever it made sense to do so.  Sort of like having a completely configurable congestion zone which can be turned on and off based on the requirements of the moment. And the zones don’t even have to be a polygon at all, any closed form, that could be drawn on a map could represent a new zone.   And of course you could have multiple layers of zones. All this could be almost instantly configurable and trial-able on a whim, like a software defined traffic management (SDTM).

I suppose one problem with using SDTM for toll pricing is that people would need to know ahead of time the cost of traveling through a zone. Maybe that’s why the token approach is better because without a token, you are directed to stop or on another route, outside or around the zone. In one waye tokens could be used as sort of a sophisticated onramp stop signal, that only allows passage when a token frees up.

Maybe token’s should be retired not just when you leave a zone but when you stop moving  or when the engine is turned off as well, that way as cars are parked, their tokens could be freed up for other cars.

How you get people to go along with the token management is another question. As the system is tracking cars automatically, one could automatically fine drivers for violating the token scheme.


Thank goodness my commute days are long gone.  I get the feeling it’s going to become a lot more interesting driving to work in the future.


Photo Credits: World Class Traffic Jam by JosieShowaa

AT&T personal hotspot on iPhone

My iPhone in Settings App
My iPhone in Settings App

I have been tied to local WIFI hot spots at most hotels and other venues for quite awhile but a recent trip to Japan where WiFi was less available, got me thinking about getting a Verizon MiFi or other personal internet device.  Some of my friends swear by the Verizon MIFI and others swear at it.

But I am sick and tired of paying $10/day for WIFI at a hotel or other venue where I happen to be at.  So I decided to go after AT&T’s hotspot for the iPhone.

I have been an iPhone user for a couple of years now and had grandfathered in an “unlimited data plan” which cost $30/month but to get the hotspot option I had to give that up for a 4GB/month which came with the hotspot option (DataPro 4GB for iPhone).

I looked back at some of my recent AT&T bills and I have been using around 250MB/month so thought this wasn’t going to be a problem. But then again, I don’t watch a lot of Netflix or Youtube video on my iPhone (at least not yet).

It turns out the iPhone hotspot has three operating modes:

  • WiFi – which allows up to 5 users to use your password protected WiFi broadcast from the iPhone.  I tried it at home and at a conference center (with lot’s of other networks active and was able to find the network without problem.
  • BlueTooth – I especially like this mode but you have to have bluetooth on for the phone and the computers you want to connect with.  Mac OSX seemed to make the blue tooth connection without problem and it was almost automatic
  • Tethered – this is where you connect your phone to the computer you are supplying internet access.  I found this approach worked great in most situations and as I looked around a recent conference hall there seemed to be a lot of laptops connected to an iPhone probably doing the same thing.

I was a little worried about AT&T’s signal strength. At home it’s not that great but I found most conferences I attend seem to be just fine.  (AT&T is offering me a free microcell for the home all I have to do is supply power and internet…).  I suppose in some major cities this can be a problem but most places I sit down to check email and other stuff on my phone AT&T’s signal strength is ok.

What about usage?

It was so easy to turn on and off (see Settings, 3rd line down from top) that I was using it only when I needed to.  My usage for the last 30days has been ~350MB received and ~60MB (according to the iPhone) sent so that is something I am going to have to watch a little more but with 4GB I seem to have room to grow.  It turns out I was at the conference for 2 nights and 3 days, but WiFi during at the convention center was free so I only used the hotspot at night or when the other WiFi was unavailable (sporadically during the day). So I seem to be using about another5 50MB of bandwidth for each night’s (probably a couple of hours) worth of work.   Which seems to say I could do this for the whole month and still have ~2.8X more bandwidth.

Well for the $15 a month extra, it seems a good deal and the best part about it is, I don’t have to haul yet another electronic device (like the MiFi) with yet another power cord/adapter. Its all tied to my iPhone which I carry around anyways.


All in all, I like the iPhone AT&T personal hotspot option.


To iPad or not to iPad – part 4

Apple iPad (wi-fi) (from
Apple iPad (wi-fi) (from

I took the iPad to another conference last month. My experience the last time I did this (see To iPad or not to iPad – part 3) made me much more leary, but I was reluctant to lug the laptop for only a 2-day trip.

Since my recent experience, I have become a bit more nuanced and realistic with my expectations for iPad use on such trips. As you may recall, I have an iPad without 3G networking.

When attending a conference and using a laptop, I occasionally take a few notes, do email, twitter, blog and other work related items. With my iPad I often take copius notes – unclear why other than it’s just easier/quicker to get out of my backpack/briefcase and start typing on. When I take fewer notes usually I don’t have a table/desk to use for the iPad and keyboard.

As for the other items email, twitter, and blogging, my iPad can do all of these items just fine with proper WiFi connectivity. Other work stuff can occasionally be done offline but occasionally requires internet access, probably ~50:50.

iPhone and iPad together

I have found that an iPhone and iPad can make a very useable combination in situations with flaky/inadequate WiFi. While the iPad can attempt to use room WiFi, the iPhone can attempt to use 3G data network to access the Internet. Mostly, the iPhone wins in these situations. This works especially well when WiFi is overtaxed at conferences. The other nice thing is that the BlueTooth (BT) keypad can be paired with either the iPad or the iPhone (it does take time, ~2-5 minutes to make the switch, so I don’t change pairing often).

So at the meeting this past month, I was doing most of my note taking and offline work items with the iPad and blogging, tweeting and emailing with the iPhone.

If the iPad WiFi was working well enough, I probably wouldn’t use the iPhone for most of this. However, I find that at many conferences and most US hotels, WiFi is either not available in the hotel room or doesn’t handle conference room demand well enough to depend on. Whereas, ATT’s 3G network seems to work just fine for most of these situations (probably because, no one is downloading YouTube videos to their iPhone).

A couple of minor quibbles

While this combination works well enough, I do have a few suggestions to make this even better to use,

  • Mouse support – Although, I love the touch screen for most tasks, editing is painful without a mouse. Envision this, you are taking notes, see an error a couple of lines back, and need to fix it. With the iPad/iPhone, one moves your hand from keypad to point to the error on the screen to correct it. Finger pointing is not as quick to re-position cursors as a mouse and until magnification kicks in obscures the error, leading to poor positioning. Using the BT keypad arrow keys are more accurate but not much faster. So, do to bad cursor positioning, I end up deleting and retyping many characters that weren’t needed. As a result, I don’t edit much on the iPad/iPhone. If a BT mouse (Apple’s magic mouse) would pair up with the iPad&iPhone editing would work much better. Alternatively, having some like the old IBM ThinkPad Trackpoint in the middle of a BT keypad would work just fine. Having the arrow keys respond much faster would even be better.
  • iPad to iPhone file transfer capability – Now that I use the iPad offline with an online iPhone, it would be nice if there was some non-Internet way to move data between the two. Perhaps using the BT’s GOEB capabilities to provide FTP-lite services would work. It wouldn’t need high bandwidth as typical use would be to only move a Pages, Numbers, or Keynote file to the iPhone for email attachment or blog posting . It would be great if this were bi-directional. Another option is supporting a USB port but would require more hardware. A BT file transfer makes more sense to me.
  • iPad battery power – Another thing I find annoying at long conferences is iPad battery power doesn’t last all day. Possibly having BT as well as WiFi active may be hurting battery life. My iPad often starts running out of power around 3pm at conferences. To conserve energy, I power down the display between note taking and this works well enough it seems. The display comes back alive whenever I hit a key on the BT keypad and often I don’t even have to retype the keystrokes used to restart the display. More battery power would help.


So great, all this works just fine domestically, but my next business trip is to Japan. To that end, I have been informed that unless I want to spend a small fortune in roaming charges, I should disable iPhone 3G data services while out of country. As such, if I only take my iPad and iPhone, I will have no email/twitter/blog access whenever WiFi is unavailable. If I took a laptop at least it could attach to an Ethernet cable if that were available. However, I have also been told that WiFi is generally more available overseas. Wish me luck.

Anyone know how prevalent WiFi is in Tokyo hotels and airports and how well it works with iPhone/iPad?

Other comments?