Asphalt Sidewalks
What's the difference between a bike trail (I dislike the term "bike trail," but that's a post for another day...) and an asphalt sidewalk? We tend to label any facility made out of concrete as a sidewalk or pedestrian facility and any facility made out of asphalt as a bike trail. In many suburban communities, it's common to see a concrete facility on one side of a roadway and an asphalt facility on the other side, the concrete being for pedestrians, the asphalt for bicycles. But other than the building material, they are essentially identical in design. They treat intersection crossings the same and they follow the same traffic control devices. Is the difference between a bike facility and a pedestrian facility really only the material used for construction?
In practice, the answer is unfortunately "yes." A major roadway near my office was recently reconstructed, which included the construction of a concrete sidewalk on one side of the street, and an asphalt "bike trail" on the other side. Other than the building material, the two are essentially the same. I usually don't like riding my bicycle on sidewalks, so it's not surprising that I've never actually ridden on the new bike trail, either. I prefer to use the roadway, where I have right-of-way and am at less risk of crashing with vehicles turning on and off the side-streets.
But that's not always the case. In fact, I prefer riding on bike trails. My daily 8 mile commute to work includes over 6 miles of bike trails, and it's not an accident that I both live and work near major bike trails. So why do I turn my nose up at the new bike trail near my office? Well, because it's essentially just an asphalt sidewalk - and if I don't like riding on concrete sidewalks, why whould I want to ride on an asphalt sidewalk?

Comments
Where is the new trail by your work?
Can you put a picture of it up so we can see what it looks like?
Thanks!
Yup
Great post. Sidewalks are not bike paths. There are many reasons for this, which can be summarized that sidewalks have always been for pedestrians. Bikes move faster and act more like motor vehicles. Putting bikes on sidewalks makes travel less safe for everyone.
A perhaps unrelated
A perhaps unrelated idiosyncrasy is that although sidewalks are often made out of concrete, joggers (who are better suited for the sidewalk) prefer blacktop over concrete because it's easier on their knees, and thus sometimes end up jogging on the road or on the bike path because of the material it's made out of.
In many ways it would actually make more sense to make bike paths out of concrete (longer lasting, and we don't have the same issues with the material that joggers do) and sidewalks out of blacktop.
How about concrete and asphalt?
In Paris, the sidewalks are made of concrete with a thin layer of asphalt over the top:
This treatment does seem to be easier on the feet and the legs in a city where walking is essential and usually the best form of transport. I wonder if this treatment would result in the best of both worlds: the durability of concrete and the extra cushion of asphalt.
The main difference between
The main difference between a bike trail and a bike sidewalk is the right of way.
If I can drive on the road and not have to stop, yet must stop on the bike path traveling the same direction. It is really just a sidewalk and even worse than a sidewalk.
Here in Arizona we have concrete MUPs . The difference between the sidewalk and a path is the dashed yellow line.