Alert sounds in Google Maps?

I'm on a long road trip, and we're relying on Google Maps to get us from point A to point B. Does anyone know if it's possible to get Google Maps to give alerts (sounds, LED) when the path indicates that you're approaching a step in the directions?

Some of our stretches between turns and interchanges are over 100 miles. It would be great if my BB could beep or something a few miles before the next step, to let us know we're going to have to do something soon.

Anyone know if this is possible? If not with GM, then maybe with another free maps app?

Thanks!!

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