Watkins, who was testifying in Costa's murder trial, also said that she saw Costa struggle to steer the truck left away from the storefront as it approached after striking cars “with such a force there were literally like sparks of light in the air.”
Palmdale resident Angel Posca, 58, and his 12-year-old daughter Angelina were killed and a dozen others were injured when Costa, 46, lost the brakes on his truck while descending Angeles Crest Highway and plowed through its busy terminus at Foothill Boulevard in La Cañada Flintridge.
The sound of Posca's sedan being crushed and then pushed forward by the impact “was like a thundering, rolling, scraping train coming,” said Watkins, who compared the rumbling of the oncoming truck to 1994's magnitude-6.7 Northridge earthquake.
Costa faces a life sentence if convicted of charges that include two counts of murder and vehicular manslaughter and three counts of reckless driving.
During opening arguments Friday, attorneys presented starkly different views of events leading up to the crash.
In a statement that culminated with jarring video of the fatal crash shot from a bus's dashboard camera, Los Angeles County Deputy District Atty. Carolina Lugo argued that Costa was aware the brakes were overheating and had been warned of the dangers of continuing along the highway's steep downgrade, but did so anyway.
Defense attorney Edward Murphy said testimony coming over the next four weeks will show that Costa properly inspected and maintained the brakes on his 18-wheeler before they quit on the highway's sudden straightaway descent into La Cañada.