I have version 9.95.0 of Google Maps. Suddenly the route adjacent to the BLue route I was using, a green road showed up next to the road I was traveling on. What's the significance of a GREEN road. Thanks.
That's usually traffic conditions. Blue is the 'normal' color or no-info-available one, but if you activate the Traffic Layer, you'll see a gradient between green (OK), yellow/orange (slower-than-average traffic), and red (slow/stopped traffic).
I think I misunderstood you then... you're talking about green roads WHILE navigating (turn-by-turn navigation), right? In that case I think the green road means that an alternate route was available while you were traveling and you are on the best route. However, since I'm not navigating at the moment I can't confirm that's true or not (I usually don't look at the map, just use the voice directions).
Has it happened again since? Is there anything special/specific about that road (restricted access or near a toll or something)? Or was it at the beginning/end of the trip?