Looking for opinions after an accident

I was filtering passed stationary traffic on a bridge going about 10mph. The traffic was stationary due to a red traffic light at the end of the bridge, there was no traffic coming towards me. About halfway across the bridge the 3rd party pulled out of the stationary traffic to pull a u-turn, I tried to avoid the collision and swerved away but he continued pulling out. Who's at fault here? I thought it was cut and dry his fault but his insurance have denied responsibility.