The Los Angeles Marathon posted this on their official website:
Having a Tough Day?
If you're having a tough day and want to end your race before 26.2, you can choose to take the turn at Mile 18 and head into the finish line early. You do not need to notify anyone of your decision and can opt to take this route at any time. This option is available for this year only.
How to find it: Just past Mile 18 on Santa Monica Blvd, look for the Charity Half Finish signage on the left side of the road. Signs, cones, and barricades will be in place to help direct you to this exit and toward the finish line.
You will still receive your finisher medal and any challenge medal you’ve earned, and your official race results will be updated at a later date to reflect your time and mileage. There is no shame in making a smart decision for your body.
REALLY??!!!