At a time when the city has doubled its demolition budget, you'd think demolition companies would be ecstatic. But some of the area's biggest contractors are considering walking away from city jobs altogether. The reason: confusion and contention about how to handle asbestos concerns during the demolition process. But because the city hopes to take down 600 houses in 2008, focusing on several neighborhoods in particular, health officials are considering extra scrutiny. Even so, the Hazelwood contract could be the last for ROAC.