Depends how much your boss likes you or if agency. You do have the advantage of this being partly a problem you likely couldn’t help so mitigating circumstances could have an advantage.
Just emphasise the fact that you needed to check on the traffic and get off the road asap, thus analysing the quality of the hard shoulder wasn’t top priority.
Btw if you are agency, dont agree to paying anything or sign anything to say it was your fault. Saves a lot of grief from slimey types.