From: Anders Sandberg (asa@nada.kth.se)
Date: Mon Feb 11 2002 - 02:47:41 MST
On Sat, Feb 09, 2002 at 07:11:26PM -0500, Dan Clemmensen wrote:
>
> Like any routing problem, this is only useful if the cost of the more
> sophisticated routing algorithms are cheaper than the cost of additional
> bandwidth (streets and highways in this case.) My area of expertise is
> routing in data networks. In data networks, even the crudest algorithms
> work perfectly well when the traffic is at 50% of the available
> bandwidth, And even the best theoretical algorithm cannot achieve 95%
> utilization with acceptable performance. In most data networks it
> is cheaper to build extra capacity than it is to deploy better routing
> algorithms. The reason the Internet works at all is that its core is
> massively underutilized.
Building new roads is very expensive at least in inner cities, so
unless the software system gets very complex and expensive it would be
worth it - at least to the drivers. In the current situation there is
less incentive for the politicians controlling the roads to make them
more efficient.
Besides, extra bandwidth does not always decrease the time it takes to
get anywhere. The Braess Paradox can complicate things:
http://tigger.uic.edu/~hagstrom/Research/braess.htm
I talked about this kind of market-based approaches to traffic planning
with a friend who is a politician involved in a lot of technical
planning in my area (he and his friends are essentially playing SimCity
with it :-). He told me there is already quite a bit of adaptivity in
many traffic lights here, although this is more like my original
proposal of having the lights react to where the bigger queues are.
According to him (too) the system might not benefit significantly with
an even cleverer lights algorithm. Still, he is looking at it from the
traffic throughput side, and not at the value to each driver. After all,
a traffic flow with slightly less efficient throughput but where people
arrive more commensurate with their perceived needs would increase the
overall utility.
-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
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