Tulips, Wooden Shoes, and High Technology
A Problem in the Streets of Amsterdam
Amsterdam is one of Europe’s most scenic cities, and an endless
stream of tourists can enumerate its many notable characteristics. Diamonds.
Tulips. Porcelain. 88 canals. 1299 bridges. And 2000 parking meters.
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Unlike the meter-per-stall
design common to North America, each Amsterdam meter dispenses printed
vouchers for several vehicles in its immediate vicinity, authorizing
parking for specific periods of time. The meters’ owner—Amsterdam
Government Parking Service—needs to access the units regularly
in order to monitor supplies (change, paper), check status (vandalism,
usage statistics), and modify tariff information.
The meters were designed to provide for such access; each incorporates
a modem and supporting software. Providing traditional telecommunication
services to 2000 meters scattered across Amsterdam’s canal-ridden
geography, however, proved to be an expensive proposition. It included
not only the cost of laying and connecting the cables, but also
regular service fees (both line rental and per-call toll charges).
A better solution was needed. |
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A Solution Already in Place
Marco Quispel, Project Manager at Amsterdam Energy, had that better idea.
The city’s electric power utility was already supplying a 220 volt
service to each of the meters. Could that connection somehow be exploited
to provide the necessary communication functions? For an answer, he turned
to Connect B.V., a LonWorks Independent Developer with over a dozen years’ experience in industrial/process control, energy management, and telecommunications.
Wil van Velzen, technical manager at Connect, describes the innovative
approach: “Amsterdam Energy already had the [electric power] wires
in place, and the meters had modem interfaces; it was simply up to us
to create the right kind of modem.” Such a power line modem was
developed using LonWorks technology. Incorporating both a Neuron®Chip
and a spread spectrum power line transceiver, the device installs easily
in the parking meter, and uses the power distribution line itself as a
network communication medium. Echelon’s PLT-30 transceiver was chosen
for its compliance with CENELEC EN50065-1, the European A-band standard
designated for outdoor (utility) power line applications.
Groups of 1–15 parking meters form local subnetworks;
standard LonWorks routers provides a transparent connection from
the power line medium to twisted-pair wires (which are also available—though
with more limited coverage—in Amsterdam Energy’s service
tunnels beneath the city). Groups of such meter subnetworks, collectively
spanning a distance of about a kilometer, are coupled through another
router to an eight kilometer “spoke.” These spokes collect
at a “hub,” where additional LonWorks routers pass the
message packets to a further kilometer of local network at the administrative
center.
Today, Parking Meters. Tomorrow,…
The success of the parking meter application has led to plans for
further uses of the far-reaching LonWorks network. On the city’s
tram lines, for instance. Each of their approximately 400 track
switches are electrically heated in order to cope with Amsterdam’s
winters. |
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Communication with each switch will allow not only control of the heater
(and the ability to avoid the load surges that would result if too many
were engaged simultaneously), but also the all important checking for
proper functioning of the unit.
And then there’s the issue of connecting, regulating, and pricing
electrical power for all those ships in the Amsterdam harbor…
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Ring Around Amsterdam
To improve communication path reliability, and cope with an ever
expanding network, the “hub and spoke” architecture
is in the process of being converted to a more robust “ring”
topology. This ring is constructed of eight kilometer segments,
initially six in number (though this will almost double as the network
is expanded). The segments are joined with Connect-designed “ring
repeaters,” based on LonWorks technology, and featuring a
self healing design: any of the ring segments can fail without interfering
with network connectivity (the failure, of course, is flagged for
immediate service).
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