Originally Posted by pannierpacker

Imagine this first picture, but without a shoulder. Then imagine there only being 1 lane to merge onto the bridge with. Then imagine biking through a cloverleaf with no shoulder. Would you want to bike in either of those locations?

Many times the city/state will refuse to put a shoulder on a bridge. Their rational is that bikes shouldn't use the road because they believe there is a safety hazard. The only way to convince these cities/states to do anything is if they can provide a safe alternative.