I can think of two dangerous sections of the Central Iowa trail system that need to be addressed. One is the new underpass of the Grand Avenue bridge on the Walnut Creek Trail and the other is the tunnel under Beaver Avenue on the Trestle to Trestle Trail. Both have BLIND spots that pose collision hazards.
The Grand Ave underpass has recently been reconstructed. Riders make a swooping 90 degree turn around the bridge support. There is no way to see what or who awaits on the otherside. I have almost collided with pedestrians and bicyclists here.
The T2T tunnel has a 90 degree turn. In the tunnel it is impossible to see who or what is coming toward the tunnel. Mary was hit by a roadie here.
Placing large television screens and cameras on the blind spots is probably too expensive but a sensor and warning light would not. When someone enters the area of concern of the blind spot a the warning light would flash to alert the unsuspecting trail user that there is a collision risk.