Avoid another (LONDON) blast

Thursday night (21/07/05) when i switched on the Television, I was shocked to see another London bombing. Just was curious to know is it possible ever to come up with a perfect solution. Here is what I thought. Not perfect but can be useful. THe government has the database of all houses in the city. If the government asks the people in one house to check some other xyz house in the city. Probably one house family can check for 4 other houses (including car) for any explosive material and update that information on website. I know we are intruding the privacy of people, but in situations like this we have to compromise. There should be strict survelliance on the roads to see if some people are dumping anything unwanted outside the house for the days the public are searching the houses. The cops can themselves cannot search each and individual houses. So this will work. What do you say?