Ok, we have a problem. There is a possible glitch in my theory.Murphy is trying to dash across Stemmons at the same time & place that Hoffman is slowly motoring his Falcon into history.
Did Murphy cross first, or did Hoffman (& passenger) pass throo first, or did they collide?
The aerial shows the problem. JFK is entering the triple underpass when the Falcon is at the start.
And Murphy is at that exact moment climbing up to stand higher in the trunk of his 3-wheeler.
Murphy wont start his dash until JFK has passed under him, his dash covers 24 yd.
Did Murphy cross first?
JFK & Co are accelerating, the underpass is 40 yd wide, the overpass is 24 yd wide, dist tween is 147 yd.
The Falcon is going slow & getting slower, & stops where shown, about 67 yd.
I have drawn the Falcon's traject in lane-3, but it could have been in lane-2 or lane-4, lane-1 & lane-5 are breakdown lanes.
Mr Passenger is all the while looking down on JFK & Co, at least he is once JFK has exited the underpass.
Murphy shortly realizes that he can't see JFK when JFK is exiting the underpass koz by standing high in the trunk the signage is now
blocking his view of JFK under the signage & he quickly jumps down onto the tarmac again.
Hoffman sees Murphy's gymnastics, his passenger yells that there is something wrong in the motorcade.
Mr Passenger hears the sirens & sees the flashing lights.
Hoffman yells back that its no good yelling at him koz he is deaf!
Mr Passenger yells back then how did Hoffman know that he was yelling!
JFK passes under Murphy & Murphy spins around to start his dash.
Hoffman sees Murphy take a step towards Hoffman's lane.
Murphy sees the Falcon & his eyes meet Hoffman's eyes.
Who blinks first?
Did Hoffman hit the brakes, or did he hit the accelerator?
Did he hit Murphy?