realistically ...

i do not believe that New Yorkers would evacuate the whole of Manhattan for a terrorist attack ... unless the attack involved NBC weapons .. possible widespread casualties. otherwise, people believe that the authorities have the ability to cordon off a specific area, and eliminate the threat. whether that's true or not, depends on your story.

a motorcycle would be an excellent way to escape the city, if your character had advance warning.

OODA loops are used for training spec forces personnel. but most normal people have no knowledge of those sophisticated things. the gut reactions of people fall into three categories .... freeze, flee, or fight.

Pete