Expect the Unexpected from Police Vehicles
I used to smile when I saw closely spaced traffic, a large gap, a police vehicle, another large gap and finally more closely spaced traffic. Everyone is afraid of the cop I thought. Having spent 25 years driving a marked police vehicle I recognize both that I rarely see this anymore and that it was a wise thing to do. Police vehicles often make unexpected starts, stops and turns.
This comes to mind as I was required as a court witness last week for a collision between a police vehicle and the civilian vehicle following it. The officer wanted to stop an oncoming vehicle so he turned on his emergency equipment, moved right, slowed and began a u-turn to pursue it. The vehicle following the police vehicle carried on as usual and tried to pass by on the left. I say tried because when the police vehicle turned left a sideswipe collision resulted.
The officer driving either failed to account for the traffic behind him or simply assumed that the vehicle following him would see the emergency lights and stay back. Either way, he was not operating in a safe manner and was charged for it. Honestly, I never thought that I would be a witness to something like this, rather I worried that I would cause a collision like this as traffic behind tended to try and get by rather than slow or stop.
That brings us full circle to the first paragraph. If you are in traffic around a police vehicle, a defensive driver will leave plenty of room for the unexpected. The two second rule is probably two seconds too short in an instance like this. Like the rest of us, officers may make mistakes and leaving a large margin of safety to slow or stop is simply good driving practice.
lights are not enough
With modern aerodynamic, low-profile light bars on top of low sedans in an ocean of SUVs, mini-vans, and pickup trucks, it's not always easy to see the emergency lights from a couple of cars behind, or in front of, a police cruiser.
This semi-invisibility makes it easier for police to lurk in traffic to catch offenders unawares, but when police NEED to be seen, they need to activate the siren as well!