Place D6 Zombie tokens next to Tile 3. Role a D10 to determine which column each token enters via, with column 1 being the column nearest Tile 2. On a 9 or 10 the Zombie is discarded. At the end of each turn, roll a D3 for each Zombie and move it that number of squares towards the other edge of the tile. Any vehicle that makes contact with a Zombie receives 1 damage. Remove the Zombie token from play when it causes damage or reaches the opposite board edge.