M4 warning non boaty

[BrendanS]

Re: Oh yes it is...........

Then why mention blue poles and SPECS in same sentence. Blue pole mounted 'cameras' are not cameras.They are very cheap and simple systems that measure speed of traffic flow for Traffic Master system. Other Traffic Master sensors are mounted on overhead bridges etc. They don't read number plates.They are all over the country.

Specs on the other hand (easy to identify as they are three elements, square in middle, round on either side) are camera systems which read number plates. Have been used in road works up and down M1 and M6 and several towns are using them. They read your number plate each time you pass them, and measure your average speed between them.

<hr width=100% size=1>Err, let me know if Depsol enters the forum, I'll go and hide

 

[Bejasus]

How it works

I was only comparing the Traffic Master cameras to the SPECS cameras in operation. Apologies if this was badly worded.

Trafficmaster claim that the system stores only part of a vehicle's registration number. They state that only the middle four characters are stored. Since most registration numbers in the UK have seven characters, there is no such thing as the middle four! The system must therefore be able to read the whole registration number in order to extract the 'middle four' characters.
Trafficmaster further claim that only a sample of vehicles is used.
It it obvious that if a given vehicle is chosen at random by one sensor, then the next sensor must read all the registration plates passing it in order to catch the vehicle. Since vehicles travel in all directions, all sensors must read all vehicles for the system to work. It may be that only a sample of registration numbers are stored for average speed calculations, but the system clearly must have the ability to capture all vehicles.

When a vehicle passes the next sensor, the time taken to travel between the two sensors can be calculated. As the distance between sensors is known, the average speed of the vehicle can be calculated. By constantly calculating the average speed of a sample of vehicles, congestion can be detected. This information is then transmitted to in-car TrafficMaster receivers.

The registration number is then allegedly discarded by the system. It is not clear what happens if the vehicle does not reach any adjacent sensor in a given time (i.e. it completes its journey or transfers to a minor route with no sensors).


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