Ladder and Log Bridge Trail
Black Diamond Natural Area Rides
The ladder bridge is a unique bike crossing over a pond fed by Ravensdale Creek.  It has two long stringers and a lattice of 3"x3" crosspieces, so you can look down into the water as you traverse it.
It is narrow, but at least it is old.  The cross pieces are rounded rather than square, so the ride is not smooth.  It is quite slippery when wet, making it a challenge for two-wheelers.
However, the bridge does have a 3/4" railing along a good part of it.
Much of the trail is singletrack, although it is rideable for trikes.
The trail to the bridge is straight in only a few places.
Some of it is quite steep.
All in all, the trail to the ladder bridge is a great ride.
The Log Bridge provides a second crossing of Ravensdale Creek to make a loop trail.  The trunk is long, skinny, and slippery.  To help people navigate the bridge, volunteers have set many nais into it for traction and strung a heavy wire across the river for balance.  The wire broke in winter storms and now dangles in the water.  Even with these aides, it would be a precarious crossing, especially carrying a bike or trike.  Even on foot, a successful trip across is unlikely.  I made it about twenty feet before falling in.