I ordered this book while researching the John Wayne Pioneer Trail, the coolest hiking/biking trail in the Northwest. As one would guess, rail-to-trail projects involve converting railroad right-of-ways into biking, rollerblading and/or pedestrian trails. Here in Seattle both the Interurban Trail and the Burke-Gillman trail owe their existence to former rail/trolley lines. The existing railroad ballast (gravel) gets filled in with finer gravel/sand, and in cities usually gets paved. Since conventional rail lines tolerate little grade, the routes tend to be flat or have a gradual incline, making them ideal for wheeled transportation. Most gravel paths in my experience can be ridden with anything at or above the 28mm tire of a typical "cross" bike. There are exceptions, such as the middle third of the Cedar River Trail between Renton and Maple Valley, and the book notes these.

Barbera opens with a little history on the rail-to-trail concept. Most projects owe their existence to "rail banks". When a railroad abandons a line, ownership reverts back to the government. Rather than give the irreplaceable right-of-ways to campaign contributors, the government keeps the land for possible future transportation needs and converts the routes to civilian use. Each trail the book gives a little history and then discusses amenities and trail conditions. A lot of the information is relevant to families. The book is split 80% Washington / %20 Oregon. I'm not sure if Washington is hipper, or if Oregon just has more rail lines still in use. Definitely a good resource for trails in the area.