Originally Posted by
John Forester
It is correct that when I first made that analysis I was thinking largely in terms of arc of vigilance. However, that also implies that the driver's mind has to consider what its eyes see. The turn across, rather than the merge first, still requires more mental consideration, starting with checking the mirror and then considering what is seen. Also, I know that I don't trust the outside mirrors to tell me that no traffic is present; they tell if some traffic is present, which is useful information, but, as the driving instructors teach, if nothing shows in the mirror, still make a direct look.
Therefore, I conclude that the direct turn across is still more dangerous than the merge before turning. And it is probably less effective, also, because with the merge first the turning driver does not have to stop, while with the turn across he must stop if bicycle traffic is there.
My mirrors allow me to have a very wide view of objects on the right side of my car; like most such mirrors, they are convex, thus allowing a wider angle of view then that offered by a flat mirror. Drivers need only develop the habit of actually using the mirror and regularly glancing at it, as they should all other mirrors, and indicators in and around their vehicle... of course this means they should not be distracted by such things as cell phones and Starbucks... neither of which was readily available 30 years ago. Of course they may need a bit more time to check all these mirrors, windows and gauges, so perhaps motorists should slow down... 30 years ago the mandatory speed limit was 55MPH and no higher; today even arterial roads may have speed limits over 55MPH.
Oddly enough, 30 years after the last "gas crisis" we are still having "issues" with gasoline...
Perhaps a better solution is needed. I tend to agree that a merge and turn is better than a direct turn... but then these traffic situations have only been studied for 30 years or so...