[quote=Halo]
Ah, but what type of rail? Wikipedia has once again astounded me by informing me that there are different classifications of railings - guardrails and handrails.
[/quote]

It's both and neither. The word 'railing' is used on its own here, but you could really apply either of those terms if you wanted to. (It's a handrail that will assist someone in climbing up and over the bridge. It's a guardrail to keep people from falling off the bridge.)