Both of those prepositions work, but along suits the context well.
along (prep.), On a line or course parallel and close to; continuously beside.
Source: along: Definition and Much More from Answers.com
Does that help?
Note on politically correct (PC) language, from a blog on I Need Some Politically Correct Help:
Question: Can someone tell me what the PC term for "blind" is?
Response: The correct term is "blind" for someone who cannot see. It is "visually impaired" for someone who can barely.
I work on a committee that is responsible for making software accessible for blind employees, and I work with blind organizations. They don't call themselves the "American Federation of the Visually [Impaired]" or the "National Association for the Visually Challenged"
Blind people actually consider it insulting that we walk around the term "Blind" as though there's something wrong with it.
Use the term that describes the person. A person that cannot see at all is not "visually impaired."
He or she is blind, and it's ok to say that out loud!