On Dec. 18, 2014, plaintiff Maria Martinez, 52, a school aide, exited a transit bus that was stopped alongside the intersection of Hoefner Avenue and Whittier Boulevard, in East Los Angeles. She claimed that the bus’s rear doors closed upon her, and she claimed that she resultantly suffered an injury of a shoulder. Martinez sued the bus’s owners and the driver’s employers, the city of Montebello and Montebello Bus Lines. The lawsuit alleged that the bus’s driver was negligent in the operation of the vehicle. The lawsuit further alleged that the defendants were vicariously liable for the driver’s actions. The lawsuit also alleged that the accident was partially a result of a dangerous condition of the bus. Martinez claimed that the closing doors trapped and injured her chest, her right arm and her right shoulder. She claimed that she suffered further injury freeing herself. She claimed that the bus’s driver immediately resumed travel without having addressed the accident. Martinez’s bus expert opined that the driver should have immediately released the air to the bus’s rear doors — thereby reducing or eliminating any physical injury — by switching a lever near the driver’s seat, but that the driver failed to do so. Martinez further claimed that she contacted the city of Montebello the next day, to request a form to report the incident. Martinez’s counsel claimed that the city should have resultantly retrieved the bus’s video surveillance tapes, to investigate the matter, but did not do so. The defense presented a city of Montebello bus mechanic, who claimed that the bus’s rear doors could only have been released using an emergency valve located near the rear doors. Defense counsel suggested that the accident did not occur or did not occur in the manner that Martinez described. He noted that, in an interrogatory response, Martinez had provided a three-hour time period in which the accident occurred, rather than a specifc time. He also noted that the city’s bus drivers are trained to stop and investigate any incident aboard a Montebello bus. Defense counsel also contended that if Martinez had provided detailed accident information when she contacted the city, the bus’s surveillance video would have been retrieved and preserved., Paramedics responded to the bus stop, and Martinez was transported to a hospital. She underwent minor treatment. Martinez ultimately claimed that she suffered a tear of her right shoulder’s rotator cuff. The injury required surgery. Martinez claimed that she suffers residual pain. The parties stipulated that Martinez’s past medical expenses totaled between $18,000 and $47,000. Martinez sought recovery of those expenses, and she sought recovery of damages for past and future pain and suffering. Defense counsel contended that Martinez’s ongoing complaints are related to other medical conditions. Defense counsel also challenged the amount of the past medical expenses.