yes, it is theoretically possible, that a dead end prevents a robot from entering the evacuation zone but I can not see a reason why a field designer should place a dead end on the tile immediately before the evacuation zone.
If you look at:
1.5.4 A dead end is when there are two green marks before an intersection (one on each side of the line), in this case the robot should turn around.
It is clear that the robot should turn around every time it faces two green marks, therefore the robot could not enter the evacuation zone. The location of a dead end on the tile before the entrance of the evacuation zone does not make any sense to me. If you look at the last paragraph of the summary, it seems clear to me that the evacuation of victims is a substantial part of the Line competition – if the robot would not be able to enter the evacuation zone, it would not be able to rescue any victims – therefore I strongly recommend any field designer to not place a dead end immediately before the entrance of the evacuation zone.
 At the end of the line there will be a rectangular room with walls (the evacuation zone). The entrance to the room will be marked with a strip of reflective silver tape on the floor. Once inside the evacuation zone, the robot should locate and transport as many live victims (reflective silver balls of 4-5 cm diameter that are electrically conductive) or dead victims (black balls of 4-5 cm diameter that are not electrically conductive) as possible to an evacuation point in one of the corners of the room. The robot can earn between 15 to 40 points for each victim depending of the difficulty level.