[Pollster1]

I would add a folding kayak to NYC preps. Then you just have to get to water instead of following many miles of roads and crossing a few bridges. There may still be obstacles getting to the water and potential pirates on the water, but they are probably a far smaller threat than the congestion and highwaymen on the roads out of the city. I imagine a 5:00 am egress to shore a few days after the city shuts down would be manageable.

[Kartographer]

One of the few good post on the thread! A person doing this would be well advised to study the rivers around New York and keep a tidel chart as the rivers are tidal and you need the tide working with you so you can get as far up stream as possible. I would also advise that you have a cache somewhere up stream NY, NJ or CT as a goal so you can travel light and fast.

[Theoria]

Great suggestion. I read this article last year, it wasn't about prepping or anything. But it gives you a idea, that your suggestion is on the right track. Doing something like that would help to keep you from trouble, and the ease of egress and plentiful food below you is something to consider.