Have a "Traffic Bar" that appear in the routes screen overlayed on the main map.
add a car to the bar that moves along with your journeys completion.
So when you are 85 percent home, the car has moved 85 percent up the bar.

Also when the Bar-Car (Maybe we should think of a better name) gets near an event an audible alert gets triggered, like when you near a Cop it could say “Oh cock, its the Rozzers!” Or just “Police reported ahead”) Or when you are near a obstacle on road you could be warned – e.g. “Johnny reported a car has stopped on the shoulder 20 minutes ago.” This way you can keep your eyes on the road instead of having to look at the screen to see what’s ahead.

The bar information would be dynamic – if traffic started building up ahead another section of the bar would change colour depending on the conditions.

Having the bar would make the app safer to it users, because you would have all warning along the route in one predictable place. Unlike the current situation where you have to zoom in and out to see what conditions are like for a entire route.

Having the bar would make the app smarter, because you would get all road information sooner. Having this information right on the bar makes for better decision making by the driver, again because all the information is visible right from the start.

Pictures posted here.
http://www.waze.com/forum/viewtopic.php?f=7&t=18010&p=161335#p161335