Blood on the streets

Quite right, an example is once a tipper leave a construction site, it's no longer their responsibility.

That's not quite correct, Ed. The Olympics, for instance, adopted a zero casualty target for its construction. I'm not quite clear on whether they met it--Charlie investigated some of this at the time and may know more. I think there was a suspicion that the lorry and driver involved in Lisa Pontecorvo's death may have been Olympics-related, but I don't think it was ever proven. I think there have been other construction projects which adopted similar policies, but you'd have to ask Charlie for details.

Make construction sites responsible for contractor they hire for example, and they'll be more concern with the number of death occurred

It's certainly true that this would improve things. One of the worst hotspots of recent years was Shard-related--the area between Tower Bridge and London Bridge, especially Tower Bridge Road and its turnings to the west towards the Shard site.