The most important ones were the turning templates of semi tractor trailers and other oversized vehicles.
To use the mini-roundabout they will have to take advantage of the "mountable curbing" that will be installed in the center. As Jeremiah Bartlett explained, vehicles (big or small) traveling over the mountable curbing will have to slow considerably as driving onto mountable curbing will damage any vehicle doing so at regular speeds. Hopefully the mountable curbing can be resilient enough to take the regular abuse.
The Portland Fire Department is also a big fan of this project. They apparently are as upset as everyone else about how dysfunctional this area is for getting through - whether or not on an emergency basis.