Mice in a trap
The walkers from Garraty's group discuss the death and why they chose to do it, and they conclude that they don't even have a good reason. All they are is "mice in a trap". This statement strengthens the feeling of hopelessness of their situation. They have no way to escape, they are trapped and by their own choice.
The road as a dark mirror
During the walk rain starts to fall down and Garraty looks at his reflection in the road which looks like a dark mirror, a black glass, and his face looks twisted. This simile represents Garraty's struggle to keep his sanity, he was beginning to feel feverish and not feeling like his legs could last much longer.
The perfect darkness of death
As the remaining walkers approach the end, and the delirious crowd watches excitedly as one by one are killed and removed the idea of death doesn't seem as bad to Garraty. He imagines the silence, the conclusion of it all, no worries left, an ending to the agonizing walk and noise-the prefect darkness of death.
