A 27-year-old motorcyclist suffered a serious leg injury on the A13 eastbound just before the Marsh Way junction on Saturday, 20 October.
His injuries are not thought to be life-threatening.
Officers want to speak to the drivers of the cars that have been circled as they may have witnessed the collision.
The driver of the other vehicle in the images stopped at the scene and is assisting police with their enquiries.
No arrests have been made.
Police are appealing for the drivers of the vehicles or any witnesses to call the Serious Collision Investigation Unit on 020 8597 4874.
