My question is are there any security measures which prevent normal traffic from entering the airport through the runway when the runway is not in use? How much security risk does such a runway intersecting with a civilian road entail?
Edit: To make the situation more realistic, assume that some very hostile elements are heading towards the airport, and maybe they need only 5 minutes to throw a grenade at an aircraft, or open fire or cause some other similar destruction. I am specifically looking at how fast would the response of airport security at Gibraltar Airport would be in such a situation, especially given that it's a small airport with only around 15 departures a day. And simply if there are any measures to prevent normal traffic from entering the airport boundary in the first place?