Part of speech: Adjective

Definition:  very strange or unusual

Source: http://www.merriam-webster.com/dictionary/%20surreal

Meaning : I saw this when I was reading the article Tunnel Rats of Atlantic Av in the lines  I got tunnel fever when I was walking to a market in Brooklyn Heights and came upon the surreal sight of ordinary folks crawling into a manhole, some of them wearing their nice clothes.

Now that I know what surreal means I think that it meant it was a very strange to the author seeing people going the manhole.