Why does the Google Lady split up my route?

[GaryV]

I've gotten used to Google Maps telling me to go so X miles on a freeway, and then when I complete those miles, it tells me to keep left or right to stay on the same route number.  Most of the time it makes sense - I might have left I-75 to get on I-475.  OK, I'll give them that, even though sometimes the "split" they choose to warn me about would never be mistaken for staying on the mainline vs. exiting.

But in the last week or so, she's breaking up city streets into mile-long segments.  3 days a week I get out of work and go to PT.  The route is to turn on to Greenfield Rd in Southfield, Michigan, go 5 1/2 miles north, turn right, and I'm there.
(I use the GPS to make sure I'm getting to my appointment on time, in case of any traffic jams.)

But the Google Lady tells me to go 2 1/2 miles.  Then she tells me to go straight to stay on Greenfield.  Then go 1 mile.  Then go straight to stay on Greenfield.  Then go one more mile and make my final turn.

Why split up a perfectly straight piece of road into 3 segments for giving directions?

This isn't the only place it has happened - it happened on a 2-mile stretch of a road in Livonia today.  Go 1 mile, then go 1 more mile.

What gives?

[roadgeek01]

This sounds like a question that you should leave for the help forums at Google. 

I hope this helps.

[usends]

I see that Google's map data depicts some segments of Greenfield as a single line (which carries both directions of traffic), and other segments as two lines separated by a median (with each line carrying one direction of traffic).  I've observed that sometimes routing algorithms get confused at the points where one line becomes two, and vice versa: the GPS thinks you have to make some conscious maneuver, when in reality you're simply continuing straight ahead on the same road.

[GaryV]

^ Good guess, but the splits happen 1 and 2 miles north of where the divided road ends.