These are the fifth and sixth missions of the game. These missions are a lot faster paced than the other missions.
On Shanty Town, you have to chase a bomb maker and kill all of the guys that are defending him.
On Construction Site, all you have to do is keep up with the bomb maker. Don’t let him get too far ahead of you are he will escape. Towards the end of the mission there will be several timed parts where you have to reach a certain point before the time expires. Keep moving and don’t stop at any place for too long or the time will run out.