I learned this from an insurance agent I know. Yeah I was surprised so don't shoot the messenger!!!
From the IL State Police: Illinois law states BOTH vehicles must adjust speed and position to avoid colliding with each other. That means the driver on the main line of the interstate AND the driver of the vehicle entering on the ramp must adjust their speed and vehicle position to not hit one another. Sometimes motorists from out of state (and even within Illinois) think they get to stay in the lane and the person on the ramp has to yield to them. This is incorrect. Unless the ramp has specific instructions (typically during construction of other special circumstances) the sign posted here which is clearly visible at converging roadways means BOTH drivers have to yield to each other. Share the road and adjust for merging traffic. We hope this helps the understanding of the sign!
(625 ILCS 5/11-905) (from Ch. 95 1/2, par. 11-905)
Sec. 11-905. Merging traffic. Notwithstanding the right-of-way provision in Section 11-901 of this Act, at an intersection where traffic lanes are provided for merging traffic the driver of each vehicle on the converging roadways is required to adjust his vehicular speed and lateral position so as to avoid a collision with another vehicle.
(Source: P.A. 100-201, eff. 8-18-17.)