I am working on a project that needs road network traffic data.
I saw the Open traffic collection on Github but the data is not what I need:
It is not detailed, there is no traffic data by road segment in France or GB for example, and it is annual. I need at least daily traffic data, like this one of Paris
Is there any source from which I can get traffic data of main countries' roads ?
This data does not exist in the format you require. You will need to source it for each country and transform it to a consistent schema to meet your needs.
The Open Traffic Collection has both annual and live data, but you’d have to go through each data set individually.
I have compiled a list of data sources myself at https://gitlab.com/traffxml/roadeagle/-/wikis/Data-Sources.
These come in many formats; you will need to parse each of them individually. Datex-II is widespread in Europe, but it is quite complex and probably covers by far more than you will ever need.
Depending on what you are trying to accomplish, you might want to look at https://gitlab.com/traffxml: I am working on a universal feed format for traffic updates. There are a few conversion libraries in Java (currently for Datex-II, which is widely used in Europe, as well as some custom formats used by Poland and Lithuania).
If you are looking for event-based data (traffic jams, accidents, roadworks, closures etc.), the TraFF format might suit your needs. It is not intended for traffic flow data (i.e. reporting on traffic density and speed), although event data can be generated from it (see the traff-eismoinfo-intensity repo for an example).
For the Netherlands, this data is available from the NDW, a cooperation of traffic management of various local and regional entities.
The data is available both real-time and (limited) historical.
The full historical data seems to be available but not as (fully) open data, as they ask you to do something that 'improves traffic flow or traffic safety' in return. Examples they give are: provide them with more data, do a quality control of their data, or making it easier for the public to use the data.
The latest data is available here: http://opendata.ndw.nu/
Unfortunately, most of the documentation seems to be in Dutch only: https://www.ndw.nu/documenten/nl/#cat_2
They also have a portal to download a limited selection of the historical data: https://dexter.ndwcloud.nu/opendata
If you want more data, you should contact them as they seem eager to cooperate.
(Note that this dataset is also included in the list provided in user149408's answer to this question, so make sure to give their answer an upvote as well if you liked mine!)
