Dod101 wrote:dealtn wrote:
Let me try again.
A road with no cars on it, and zero density, has zero chance of an accident on it. A road packed with cars has almost zero traffic flow and close to zero chance of an accident. Any such accident will be low impact and non-fatal.
Between those 2 extremes lie a "curve" of increasing probability of accidents, and fatality outcomes, rising from both sides, until the point they meet to make a single curve.
Changing from a 4 lane smart motorway (with no hard shoulder) to that same road space now used as a 3 lane non-smart motorway with a hard shoulder, changes the density of that road space, and the position on its probability "curve".
This is not a discussion that is going to get either of us very far but in your example, I guess it depends, as always.If you leave out any reference to a hard shoulder I would agree with you, assuming of course that we have the same volume of traffic trying to use the one road as the other but a very high density use is as you have said, going to slow the traffic such that the chances of a serious accident is very low. And of course you appear to have omitted the benefit of the hard shoulder on the here lane motorway. It was not on grounds of safety that the so called Smart motorway was introduced anyway, but to try to improve the traffic flow, which, in your example, will increase the chances of an accident anyway. I simply do not accept that a four lane no hard shoulder motorway is going to be safer then. Three lane motorway with a hard shoulder.
Dod
Frankly I think you’re both arguing about a non-issue.
All-lane running (ie using a former hard shoulder as a running lane all the time) is no doubt more dangerous than having a hard shoulder. However, unless we find a few bn down the back of the sofa to built additional lanes, that’s irrelevant.
The key question is whether these are a reasonably safe way of adding capacity, given finite resources. I have seen no evidence that smart motorways are more dangerous than alternative non-motorway roads. As has been said, we have had roads without hard shoulders (and without any ‘smart’ monitoring) for years.
By a parallel, after 9/11, lots of Americans got scared of flying and drove instead. There was an appreciable increase in road deaths, enough to have offset 9/11 becoming an annual event in terms of passenger fatalities.
Similarly, I would be prepared to bet that more people will die on the other roads they will be forced to take to avoid increased congeestion on the non-smart motorways, than would have died if these smart motorways were constructed.