On some road trips, cables can be seen on the pavement, which raises the questions: what are they for? Why are these cables installed?
The cables that we see on the roads are actually rubber pneumatic hoses and contain air inside. They’re hooked up to sensors that detect changes in pressure, so every time a car passes they send out a signal. This type of pipe is used to measure traffic, i.e. count how many cars pass per minute, per hour or per day.
This makes it possible, for example, to determine whether traffic lights should be installed on the traffic lanes or whether traffic should be streamlined. They can even be used to anticipate a widening of the lanes. In the case of major arteries located in cities, these pipes are used to measure the density of vehicles over a given period.
The pipes not only capture the number of passing cars, but also their speed and the type of vehicles, i.e. whether they are motorbikes, trucks or buses.
One of the advantages of using these pipes is that they can detect driving habits on a road. In addition, they are used before starting any work on a traffic lane, as well as to assess whether a change in signage is necessary, depending on the density and driving style of users. Other advantages are their economical cost and ease of installation. They are laid on the floor, glued and connected to the software or meter which does the rest of the work.
As for the cons, they can wear out quickly from the outside, due to constant contact with many vehicles. This is why sometimes they are replaced by a manual counting. Other times, road services prefer to make a statistical estimate, where a mathematical calculation based on the traffic volume of previous years results in an estimated average.
Another method of measurement is the use of radars which record a signal each time a vehicle passes, much like pneumatic pipes which record the time and speed of cars. There is also another system called “electrical contacts” which activates and turns on a light whenever a car passes over it.