Who is at fault if car one has been pushed from a service ramp onto the main highway by two?

There is not enough information provided to definitively determine fault in this scenario. Typically, in a situation where one car is pushed or forced onto a highway by another vehicle, the driver of the pushing car would be considered at fault. However, there may be other factors or circumstances that could influence liability, such as the actions or negligence of the driver of the pushed car or the presence of any extenuating circumstances. Without a full understanding of the events leading up to the incident and the specific traffic laws and regulations in the jurisdiction where it occurred, it is not possible to make a conclusive determination of fault.