Accidents on the interstate are less common than crashes on other types of roads because traffic is controlled. Drivers are always heading in the same direction, and they only enter the flow of traffic through an on-ramp. This is vastly safer than two-way roads, where drivers use their judgment about when to execute turns or cross oncoming traffic.
But accidents can sometimes still happen at these merge points. When a driver is entering the interstate, using an on-ramp, they may sideswipe a vehicle that is already on the road.
Which driver has to adjust their speed?
Often, this conflict comes down to a disagreement about which driver is responsible for making the merge safely. The driver who is already on the road will feel that the driver who is entering the highway has a responsibility to speed up or slow down to do so safely. But the driver who is merging may feel like they have very little time to make that decision, so they think the drivers on the interstate should adjust their speed or switch lanes to allow them to merge successfully.
It is true that drivers who are already on the roadway will sometimes move into the left lane, speed up or slow down to accommodate a merge. But that is simply their way of being helpful. They have no obligation to adjust their rate of travel. The obligation lies with the driver who is entering the roadway to use the on-ramp effectively, find an opening, and then adjust their speed so that they smoothly fit into the flow of traffic.
When drivers disagree about who caused a car accident, it can make the case contentious. Those involved need to know what legal options they have.