Took me a bit of time to figure out why there was a ring of familiarity route-wise with this story but it finally clicked in. Some time ago I had this awful phobia about bridges so was uptight after traveling E over Tappan Zee. Was to head south on the Sprain Brook Pkwy but had to go N then exit, cross under and enter to go S. Because I was still hyped about the bridge went right past the NY-100B exit and ended up taking the exit for NY-100 off Taconic which brought me to Pleasantville Rd, at which point realized I'd screwed up and grabbed the Taconic S which is right before the Taconic overpass.
Although it's clear DS was DUI, so disoriented etc perhaps certain things triggered a response, like the Rte being 100 and than spatial issues came into play. If you follow the NY-100 path from exit along Pleasantville Rd to the right turn into exit ramp of Taconic it has a similar, albeit larger, path as the NY-100B path to get on Sprain Brook Pkwy S. Perhaps she missed (so to speak) the rte 100B exit and took the Taconic rte 100N exit and her incapacitated mind just traveled by distorted auto pilot moves. She may have 'thought' she was on Dobbs Ferry Rd.
Be interested to see what others think.
Starting from I-287 E/I-87 S
1 Head southeast on I-287 E - go 2.7 mi Partial toll road
2 Take exit 3 for Sprain Pkwy toward New York City - go 0.3 mi
3 Merge onto Sprain Brook Pkwy - go 4.7 mi
4 Take the JACKSON Ave exit - go 0.2 mi
5 Turn left at Old Jackson Ave - go 0.1 mi
6 Take the ramp onto Sprain Brook Pkwy - go 2.4 mi
Arriving at Sprain Brook Pkwy
Total: 10.5 mi - about 13 mins
From Sprain Brook Pkwy to West Babylon.
1 Head northeast on Sprain Brook Pkwy - 1.4 mi
2 Take the NY-100B exit toward Ardsley - 0.1 mi
3 Turn right at Dobbs Ferry Rd/NY-100B (signs for Ardsley) - 0.2 mi
From Sprain Brook Pkwy to Pleasantville Rd.
1 Head northeast on Sprain Brook Pkwy - go 6.4 mi
2 Continue on Taconic State Pkwy N - go 1.8 mi
3 Take the exit onto NY-100 N/NY-9A N - go 1.4 mi
4 Take the PLEASANTVILLE Rd exit - go 413 ft
5 Turn right at Pleasantville Rd - go 82 ft
Arriving at Pleasantville Rd Total: 9.7 mi - about 11 mins
Approx start to finish time: 24 mins.
http://maps.google.com/maps/ms?hl=en&ie=UTF8&split=0&gl=us&ei=AjhBSryIJJOXlAeBo83uCA&t=h&mhttp://maps.google.com/maps/ms?hl=e....063174,-73.859496&spn=0.015855,0.038581&z=15