They tend to be significantly larger in new construction because small ones don’t really cost a lot less than big ones and most designs prefer to do something nice with the landscaping. Plus, bigger ones flow better. But you can retrofit ones that aren’t vastly larger in size.
All of this is equally true of a road with bike lanes vs one without them… yet cities always seem to be able to find the space, typically by dieting the road a bit. There’s typically lots of options. Narrow lanes, reduce lanes, eliminate some/all on-street parking, cannibalize the median, etc…
Neighborhood traffic circles are a pretty easy drop-in replacement for most of the worst-offender small intersections, too, and they can be achieved with as little as painted lines.
They tend to be significantly larger in new construction because small ones don’t really cost a lot less than big ones and most designs prefer to do something nice with the landscaping. Plus, bigger ones flow better. But you can retrofit ones that aren’t vastly larger in size.
All of this is equally true of a road with bike lanes vs one without them… yet cities always seem to be able to find the space, typically by dieting the road a bit. There’s typically lots of options. Narrow lanes, reduce lanes, eliminate some/all on-street parking, cannibalize the median, etc…
Neighborhood traffic circles are a pretty easy drop-in replacement for most of the worst-offender small intersections, too, and they can be achieved with as little as painted lines.