The red rectangle is where the bridge is at 16th. Before it opened, you had to go all the way to one of the red circles. Pretty ridiculous to expect people to walk up to three miles to get somewhere that's essentially one block over. It probably wouldn't have happened if the bridge wasn't also carrying drainage pipes, or at least not for many years to come.
But it's here, and it's great. It has a switchback in it since the difference in heights is pretty big, but there are also stairs in the middle so it's optional. On the waterfront side, stairs wrap around or you can take an elevator.
It's even worth a trip or two over the bridge when it's not a shortcut. This morning I climbed it and walked along Grand instead of Marine View Drive for a quieter and more scenic morning even though it was completely out of the way.