In any discussion about cycling in Germany, sooner or later some geek who has been exposed to USENET shows up and then the ADFC #173 (http://bernd.sluka.de/Radfahren/fdf173.pdf) is being quoted. That’s a thing from 1992.
Here is a bunch of more recent material and links.
The TL;DR is:
When there is no proper traffic separation or traffic separation is impossible, then an on-the-road cycle path, is usually better than a cycle path that runs more or less invisibly by the road and then suddenly intersects with the road at crossings.
But a cycle path on the road, not separated by traffic has a number of drawbacks – paint is never enough.
- It reduces cycling in “weak” cyclists, very young and older people, feeling insecure close to cars.
- It prevents wide cycle path, and prevents “social” cycling, that is, usually two cyclists can’t be riding side by side, talking while cycling, like people in a car would be able to do it.
- It comes with speed limits on the car in order to be safe. In the Netherlands, cycle lanes on roads come with a 30 km/h speed limit recommended for cars, and a 50 km/h absolute limit.
A View from the Cycle Path is generally a recommended blog. They have an article about On The Road Cycle Lanes, done properly and improperly.
The What’s Better section at the end of the article discusses better solutions: Separate cycle paths with roundabouts, and unravelling (completely separate, intersection free infrastructures for different types of traffic). The Cycle Paths tag in the blog shows a lot of examples.
Another article explains safe roundabouts for bike lanes crossing road safely at intersections.
The keys to the design are: The cycle path is led in a way that the cyclists are forced to slow down exactly at the dangerous point, and not before, accelerating into a danger zone, and the road is led in a way that motorists have to deal only with one danger at a time, and always into the same direction, right-ahead (two o’clock), and have adequate room to stop and wait.
BTW, separation of on-the-road cycle paths can be relatively simple and cheap, as shown by this Guerilla improvement action using toilet plungers.
Social aspects of cycling are also being discussed in that blog.
How did the Netherlands become such a good country for cycling?