This is the horrifying moment an out-of-control car drove off a main highway in San Francisco. <br /><br />The dashcam footage, captured on January 26, shows the vehicle changing lanes whilst driving along the road at high speed.<br /><br />The car then seems to lose control and crashes into a traffic sign as it plunges off the road.<br /><br />The witness writes: ''It appeared that the driver was swaying side to side in the driver's seat prior to the crash."<br /><br />''Prior to the crash you can see the car make a weird and illegal lane change.''
