It could be an issue with the map in the area, if Waze doesn't think the side roads will be faster, or it could be http://www.waze.com/forum/viewtopic.php?f=6&t=15148.

Basically the traffic re-routing functionality in Waze does not seem to be 100% reliable due to multiple issues that are covered in other threads. Hopefully Waze is looking into these issues and working on a fix...

I'm a huge Waze fan. But it always takes me the same route regardless of traffic and I have started to wonder if it really is taking traffic into account when it routes me.

I have been rerouted a grand total of once in the months I have been using the app.

I wish the client was more forthcoming with routes. There are times when it gives me a funky route on the way home from work and I ignore it, only to find myself stuck in some oddball traffic because of a wreck or an interstate backup (which pours out to the road I drive home on), etc, and usually when I get there I find Waze did know about the slowdown.

So I ignored its instructions, my fault, but it'd be nice if it gave some sort of indication why. If I knew it was because of traffic, I'd have gone the back way route it suggested!

To your specific post, I've seen Waze sometimes seemingly ignore traffic, other times it aggressively routes around it. I suspect, again, it's making reasonable calculations but doesn't inform the user why. It could be the traffic penalty is less than an alternate route. However, Waze can't known every road. Roads that are bumper to bumper for an hour in the morning and evening are clear sailing during other hours, etc..

It looks like the thread you sent me to
*sigh*
Today when it happened the ETA was just not reflecting the traffic. I was sitting dead on the road with 7 miles to go and it was saying I'd be home in like 10 minutes, should have been more like 40 with the way it was going.

I noticed yesterday Waze had me sitting at left turn lights.

Either something changed or my earlier experience was just a coincidence but it seemed earlier that waze would route me around sitting at turn lights.

I do have minimize turns checked as well.