This, which can be found referring to any speed limit, not just 40mph, was actually said by a councillor recently in an attempt to oppose a cycle lane on a wide main road.
As far as I know, there is no law of physics that determines that a road must have any particular speed limit (and I do have a PhD in physics). In fact, a simple calculation shows that reducing speed from 40mph to 30mph costs a maximum of 30 seconds per mile. On a 5 mile long road, that would be 2.5 minutes, even if it were possible to travel at the speed limit for the whole length, which it usually isn’t.
Compromising the safety of people on cycles and on foot – of children and elderly people – for the sake of delays that are in practice considerably less than 2.5 minutes seems like the action of a pyschopath, and at the very least is incredibly selfish.
To see how much worse cycle lanes make conditions for cyclists take a look at:
http://www.warringtoncyclecampaign.co.uk/report/cycle-lanes.pdf
Of course they can and are put on roads with any speed limit, but if your councillor is opposing one for whatever reason then he would get my vote.
The painted lines you show in that report do not even qualify as “cycle infrastructure” according to LTN1/20 Cycle Infrastructure Design (DfT). Several councillors here are opposing *protected* cycleways on the road shown in the picture. I have another myth-buster for people who claim that those are bad for people on cycles: http://www.happycyclist.org/?p=2521
Yes, painted lanes on the road – that is what cycle lanes are. They plague the streets of Greater Manchester (most of them thinner than the one in the study) and need to go. While noone will openly admit to supporting them they are mightily resistent to removing them. It is good that at least one councilor is opposing them.
By all means ignore the actual response and reply to a response that you have just imagined instead because it happens to suit a particular narrative.