Work on the runways at Los Angeles International Airport will mean some flight delays starting in March.
A federal mandate requires that airports provide buffer zones at the ends of runways to give planes an extra margin of safety if they overshoot takeoffs or landings.
LAX already has buffer zones, but they need work to meet federal guidelines.
The board of airport commissioners on Thursday approved a $25 million contract for buffer zonework on the first of four runways that need it.
Runway closures will be phased to minimize passenger disruptions, but the airport says somedelays are inevitable.
The projects are projected to be finished by June 2018.