google distancematrix api - Errant Distance Results -

the 2 urls below generating vastly different results. each target same destination lat/lng , 2 origins less 5 miles apart driving (3.5 miles apart directly):

https://maps.googleapis.com/maps/api/distancematrix/xml?origins=38.9768,-76.7831&destinations=38.173478,-75.947092&key=xxx&units=imperial&avoid=tolls

https://maps.googleapis.com/maps/api/distancematrix/xml?origins=38.9695,-76.8472&destinations=38.173478,-75.947092&key=xxx&units=imperial&avoid=tolls

as you'll notice, results first url 136 miles , results second url 258 miles.

this odd, considering 2 origins lat/lng points in same town.

if remove "avoid=tolls" restrictive flag, second url produces result of 142 miles, correct.

all of appears avoiding chesapeake bay bridge. however, distance matrix api avoiding $4.00 bridge w/ additional 100 miles of driving when leave north side of town not when leave south side of town.

shaking head. ideas out there?