Prepositions- Along

Question

He was walking along the street when he bumped into Harry.

He was walking down the street when he bumped into Harry.

Do both the sentences mean the same thing?

On this site, the meaning of the second idiom "Walking along something" means to move beside something on foot. So, if we go by the 2nd idiom on the site, shouldn't the first sentence mean he was walking beside the street when he bumped into Harry?

http://idioms.thefreedictionary.com/walk+along

Oh, and here's the site i was talking about. ^

Answer 1

The Free Dictionary is misleading. Walk along X means "walk alongside X" only if X is not a surface which can be walked on such as a wall, as in your second example, or a river. But if X designates a path it implies that you are on the path and walking "down" it, traversing some part of its length.