Ok so getting a broken leg and having to crawl for hours, often threw heavily bandit camped areas to find a fix is a huge pain in the ass. To me it also breaks the immersion, leg bones are really strong and they are not that easy to break unless you really know what your doing. (What is this a town full of Zombie Shaolin Monks) But I agree that the Z's need to stay VERY dangerous and there should be a mechanic that makes coming in contact with them a risky bet at best. I also feel there is a classic zombie mechanic that has been left out of this game so far. So what I was thinking is replace the broken leg with an infected bite wound. The bite would give you a fever that will slowly drain blood/health over time, and then as the fever gets higher the speed you lose blood would get faster until... well you die. Now to cure this fever from your infected bite you need antibiotics. This would spawn in the same places and at the same rate as the morphine. Once infected you can still be mobile but you are on the clock to find a cure if you don't have any with you. This gets rid of the huge pain of having to crawl for hours but adds in the increasing pressure of desperately trying to find something to cure the infection before time runs out. At the same time this keeps any contact with zombies very dangerous.