Convoy (Melbourne House)

From the book "Commodore 64 Games Book 2". You are floating on an underground river and must blow up portions of the road above in order to drop the black trucks into the river. The red trucks must not fall into the river and the black trucks must not escape at the left side of the screen. By pressing the space bar, you either deposit a bomb or patch up the road, depending on your position. The seconds left for the fuse are at bottom left of screen.