Runway safety improvements under way at SFO (pictures)

Two commercial passenger jets prepare to land on parallel runways 28L and 28R at San Francisco International Airport on Thursday, March 20, 2014.

Construction work has already begun on the Runway Safety Area (RSA) at one end of Runway 1 Left, though the heavy work will begin when the runways are closed in May.

An aircraft lines up for departure on 1 Right, which will also close until September. In the background is SFO's new control tower.

Here you can see just how close the affected runways are to the 101 freeway that borders the airport.

A map of of SFO showing runway locations and the new taxiways. The new EMAS materials will be installed in the green areas.

The EMAS technology works like a runaway-truck ramp for airplanes, collapsing to assist in the slowing of planes that might overshoot the runway.

The EMAS material that will be installed collapses on impact, slowing a plane that has gone off the runway.

The EMAS tiles will line the beginning and end of Runways 1 Left and 1 Right. Here you can see where they will be installed next to San Francisco Bay.

Across the field, a KLM MD-11 arrives from Amsterdam.

As we toured the airport's perimeter, signs like this one warned us when we were about to cross a runway's end.

An Air China Boeing 777 passes over the Runway Safety Area at the end of Runway 28 Right just before touchdown. The installation of these RSAs was completed last year.

As an ANA Boeing 777 awaits takeoff clearance on 28 Left, a small private plane arrives on 28 Right. The construction closure means that all departing and arriving traffic will be restricted to these two runways. Close operation like this, however, will be permitted only in good weather.

Mind the jet blast.

A Portland, Ore.-bound Alaska Airlines Bombardier Q400.

Virgin America maintains its hub at SFO.

American Airlines' retrojet pays a visit to SFO.

A United Express Embrarer 120 Brasilia climbs out on a short-haul flight.

A Boeing 777 taxis for departure to Korea.

The 777 is one of the largest aircraft to operate at SFO.

Qatar Airways doesn't serve SFO, but one of its Airbus A340s was parked in a remote area.

A United Boeing 787 Dreamliner parked at its gate at SFO's International Terminal.