China recently held air force training exercises involving the use of designated stretches of highway for emergency airfields for fighters and transports. The first time this was done was in 1989 and so far it is known that ten stretches of highway in Liaoning (adjacent to North Korea), Shandong (facing South Korea across the Yellow Sea) and Fujian (opposite Taiwan) provinces have been designated for such emergency use. There may be others that have been designated but not practiced on, so their location can be kept secret.
China is following the example of Taiwan which began regularly practiced using highways as emergency air strips for fighter aircraft back in the 1970s. Then that sort of thing was halted for 26 years as Taiwan tried to make peace with China. In 2004 the highway landings were resumed, and now it's done every few years. There is some preparation involved, at least for the peacetime drills. Troops walk down the length of highway to be used and remove any rocks or other objects that the aircraft wheels might hit. Then cars go down the road, honking their horns, to flush out any birds who might be sucked into the jets air intakes. At that point, the F-16s can come in and land. And then turn around and take off again. China apparently follows the same drill as the Taiwanese.
Taiwan resumed these drills in 2004 and included actual use of superhighways as secondary air fields for combat aircraft in their military exercises. For example in one publicized event two Mirage 2000 fighters landed on a highway were serviced (can include refueling, rearming or minor repairs) and took off again. Parts of Taiwan's system of superhighways were designed just for this purpose but actual use of the highways during training exercises lapsed for over two decades because the Defense Ministry did not want to block traffic or annoy China. The resumed training exercises on highways was done more for diplomatic reasons; to remind China that Taiwan had many defensive capabilities. In 2007, the highway drill was carried out once more, and again in 2011.
But since 2004, the government has admitted that they are more concerned about what over 1,600 ballistic missiles China has stationed within range of Taiwan could do to Taiwanese airbases in time of war. Thus the highway landing drills are becoming more practical than political.