Dead Air (2009)

Late night shock jock Logan, his sidekick Gil, and their crew are having a normal night at work when a caller tells them of a riot that's broken out near the sports stadium.  At first it appears to be some sort of fight, but as the violence spreads, it becomes apparent that the attacks are unprovoked.

The city is being over taken by mobs of crazed people trying to kill everyone in their paths.  This turns out to be the work of terrorists who have unleashed chemical bombs at the stadium.  The bombs have a virus that causes people to get sick, die, and go into attack mode.

As the radio personnel realize that something is very wrong, they barricade themselves in the studio which is on an upper floor of the building.  When Logan can't get hold of his wife and child, Gil volunteers to check on them since he has a motorcycle and should be able to squeeze through any traffic jams.

The biggest problem with this one is that the characters do really stupid things that do not bode well for their survival.  For example, the building has a garage and they've shut the gates to keep the zombies out.  But when Gil goes out on his motorcycle, no one shuts the gates after him.  Also if the city is overrun by zombies, it's not a great idea to go out on a motorcycle as swarms of zombies can block your path. If you run over one or crash trying to get away, you're finished.  Also you have no protection as you ride through the zombies, so they might be able to knock you off your bike.

Also why do people in movies never think about the effects of a bite from an insane person with blood lust, who is possibly dead?  It's not like zombie mythology isn't prevalent in our society.  But most films usually ignore that.