On the Paris network, the majority of traffic is measured by electromagnetic loops located in the roadway.

The data are raw without any interpretation or analysis. They give an overview of the occupancy rate and the flow rate on more than 3000 track sections.

Two types of data are thus produced:

• The Occupancy Rate which corresponds to the time of presence of vehicles on the loop as a percentage of a fixed time interval (one hour for the data provided). Thus, 25% occupancy rate over one hour means that vehicles were present on the loop for 15 minutes. The rate provides information on traffic congestion. The layout of the loops is designed so as to be able to deduce, from a punctual measurement, the state of the traffic on an arc.
• The Throughput which is the number of vehicles having passed the metering point during a fixed time interval (one hour for the data provided).

The coupled observation at a point of the occupancy rate and the throughput makes it possible to characterize the traffic.

The equipment of the Parisian network: The main axes of the City of Paris are equipped with counting stations for vehicles and measuring the occupancy rate, for the purposes of both traffic regulation and public transport, information to users (broadcast on the Sytadin site), and study.

There are two types of stations on the network:

• stations for measuring the occupancy rate alone
• stations for both measuring the rate and counting vehicles.

The rate measurement stations are set up very regularly: they provide detailed knowledge of traffic conditions.

The debit stations are less numerous, and generally located between the main intersections. In fact, the flow is generally maintained over a section between two large intersections.

Geographical coverage: Paris