I decided to make one more version of the animation using bitmap versus jpeg frames, along with removal of more blurry frames and application of sharpening. The effort paid off as this scene was not evident to me in the earlier versions.
The action NW of the Hines/Industrial intersection begins near mid frame and extends westward to the upper left of the frame. The early frames show one and maybe two cars moving NW on Harry Hines towards Parkland Memorial Hospital. Shortly, near mid frame, a police motorcycle will pass those cars as the cars come to a stop. As the first motorcycle leaves the frame a second motorcycle cop follows the same path, maybe 75 feet behind the first motorcycle. Near the end of the animation at the left side a third and then fourth motorcyclist enters, about 75 feet behind the second motorcycle. At the scale of the animation the motorcycles policemen appear little more than black dots. The animation will repeat after a three second delay.
I wonder if the Hines/Industrial intersection was yet under police control. Here are the police radio logs taken from JFK First Day Evidence (Gary Savage):
Police Radio Logs Excerpts
Channel I
p387-388
12:34:25 Disp Report to Inwood and Stemmons and cut all traffic for the ambulance headed to
Parkland. Code 3
12:34:32 (24) Inwood and Stemmons?
12:34:35 Disp Inwood and Stemmons, where they come off Stemmons, going to Parkland.
12:34:40 (24) 10-4
12:34:43 Disp Make your assignment Code, 24
12:34:45 (24) 10-4
12:35:38 Ch2Disp Attention all emergency equipment. Attention all emergency equipment. Do not
use Industrial Boulevard..Do not use Industrial Boulevard. 12:36
12:36:36 (Disp) ..Inwood and Stemmons and assist 24...21., go up there to Hines and cut that
service road off there where that ambulance can go on to Parkland.
And on Channel II
p406-407
12:35 (15-2) (The) Captain advises, have all emergency traffic use some route besides
Industrial. Have 283 cut the traffic at Hines and Industrial.
12:35 Disp 10-4. 283 cut traffic, Hines and Industrial. 283, cut traffic Hines and Industrial.
(then using simultaneous broadcast)
12:36 Disp Attention all emergency equipment...Attention all emergency equipment...Do not
use Industrial Boulevard, 12:36
12:36 (220) Where do you want traffic cut in that area [Parkland]?
Disp Keep all traffic out of the emergency entrance to Parkland Hospital, and all
emergency equipment off of Industrial Boulevard.
(125) We have the emergency entrance secure at Parkland.
12:37 Disp 10-4, 125, 12:37