As Shockwave has noted, Derail is unafraid of death. Frankly, he's not afraid of anything. This doesn't make him stupid, however. An explosives expert who stores his gear in his considerably large and armored altmode, Derail is fully aware of the fact that his allies could be blown to bits just as easily as his enemies and gladly heals his comrades right up. Winning the war is a team effort, and he's a team player.
His alt-mode is a Mine clearer.