New TfL's HGV's can't see you for s*** poster

Absence of cycle lanes will never stop undertaking. As well as those determined to get ahead, i think virtual cycle lanes tend to occur on roads even without any paint. Cars pull out to overtake cyclists between junctions, then if there is enough room (and particularly if there are more cyclists around) they tend to keep out as they approach junctions.

But painted cycle lanes invite you to pay less attention to what you are undertaking. The highway code even allows undertaking by cars when the vehicles in the outer lane are in a slow moving queue. Cyclists reasonably take the same approach, only to get caught out when their cycle lane fails to provide the right of way that a full lane would. Cycle lanes are dangerous because they promise more than they deliver.

In theory there are two possible solutions to this problem. Stop cyclists undertaking lorries, or make it safe for cyclists to undertake lorries.

Doing a bit of both isn't necessarily good: If most cyclists don't undertake lorries, the risk to the few who don't know better will go up. If it's mostly safe to undertake lorries, more people will do it casually and be caught out when it isn't.

And looking closer there are more problems with both solutions: Stopping cyclists undertaking does nothing for the ones who are overtaken by a lorry, while the size and geometry of lorries (let alone the costs and legal inertia) probably make it impossible to ever make undertaking sufficiently safe.

To actually improve things, both sides need to take more care, and technical fixes can help by making that care easier and more effective. Cycle lanes are a poor solution because although they encourage motorists to take more care, they also enocurage cyclists to take less care.