Although my walk through different types of sensors was not exhaustive I hope two messages came out clear:
- there are plenty of technologies available for sensing a broad variety of parameters, and more will become available
- cities should sense their environment because the more data they have available the smarter their choices
Re-reading what I wrote as possible use, in the smart city context, of the various types of sensors you should notice that a municipality has a broad range of choices. Suppose you want to get info on the traffic flow in your city. You can get a broad “sense” on the number and types of vehicles by placing microphones in several points across the city. This can provide rough data on traffic density and traffic jams. You can deploy magneto sensors at relevant crossing points providing a real time stream of data as vehicles go through the intersection.
Alternatively, you can deploy optical sensors, video cameras, on those same intersection and have a software “looking” at the video stream to count the cars. The software could also identify each car by looking at its plate and “follow” its journey as it move from one intersection to the next one equipped with the video camera. This would provide better information on traffic flow but, of course, brings along privacy issues since now the Municipality is actually tracking its citizens…
Notice that you can also try to use existing video cameras deployed by private parties for security monitoring, and you can use the illumination infrastructure, light poles, as both places to hook the video camera (and power it) and as data transport infrastructure.
You may enforce the use of transponders on cars (as it is the case in Singapore), and/or you can get data from the vehicle GPS, and you can track the vehicles as they get close to “gate” points by using radio signals (electromagnetic sensors). Given the radio coverage you get a better localization of vehicles and you can use this more refined pinpointing to offer services (or to charge for the use of city infrastructures, like roads and parking lots).
You may get data from the wireless operators and track the movements of cell phones (with varying degree of anonimity) and by analysing those movements the software can distinguish between traffic on foot, on a private vehicle and on public trasportation. You can also profile the vehicle (and the cell phone users) and provide services based on the traffic situation and on your expectation of direction (he is going to work, to school…). Privacy is at the forefront, of course.
In this example, but it can be told the same story for many other situations, I have offered 6 different types of sensors to monitor traffic flows. Hence the question: which is the right one to use?
Answer: there is no such a thing as “the right one”. It depends on what you have and what you (and the citizenship) want to do. This is why different cities are taking different decisions. The crucial point for the decision maker is to be fully aware of what the alternatives are and of their present and future implications. This also requires a good understanding of technology capability and evolution.
As a rule of thumb I would suggest to start looking at the choices from the point of view of economics, hence:
- try to use what is already available, both in terms of sensors and in terms of communicationssupport infrastructures. One thing that is surely available are the citizens, their vehicles and their smart phones. Try first to see what needs to be done to leverage from them.
- piggy back on existing infrastructures, including communication infrastructures and their cabinets, their radio towers, the illumination infrastructure with its light poles, the public transportation infrastructure (e.g. you can easily place a video camera on every public bus and get video feeds that could be analysed to monitor the traffic flow).
- go virtual, use as much as possible different sources of data and see what information can be extracted from them. Open up these data sets so that third parties can come up with new ideas for leveraging them
- as a last resort start planning to deploy new sensors and try to be as general as possible. Rather than deploying a sensor that provides just one type of data look for something that can be programmed to deliver a variety of parameters and use it to become part of the city sensing infrastucture not just to serve a vertical application.
Does it make sense? (pun intended)