I share Brucie's concerns about transporting highly infectous agents in urban areas, but I don't know if restricting labs working with such agents to remote areas is a solution. From the bad guys' point of view, hijacking that lone Fedex van on a five-mile stretch of empty road that leads to a known facility is more likely to yield a payoff than randomly hiting one of the hundreds of vans that are making deliveries in the city. Lots fewer witnesses and cops around, too.