Dear LowEndUser,
I know that a lot of people have already advised you to build more workers, but I'm afraid that you'll still be going like; 'yes, more workers, but that means less military, that leaves me more vulnerable to attack...'.
You're worrying about defence. I'd like to give the following observation:
Take a horse, a simple horse. It's got a movement of 2. It can go 2 tiles one way, it can go 2 tiles the other way. A tile less if there's a forest or something else impeding it. That's without roads. Your horse has a radius it can defend that isn't big in an empire without roads.
Now take that same horse and put it in an empire with roads. Roads increase movement by a factor 3. Your horse, that earlier could go 2 tiles, now can go 6 tiles. It can go 6 tiles one way, it can go 6 tiles the other way. That's a diameter of 12 tiles. Actually 13; there's also the tile the horse is standing on. This means that a horse can actually defend an area the full with of your empire as you've posted it in post #50, provided there are roads.
Because roads increase the movement rate of your units by a factor 3, this effectively means that in a roaded empire you would only need a third of the military units to still have the same cover against an initial attack compared to an unroaded empire.
Of course, in a real game there will be restrictions of all sorts, but in general: the better your roads, the less units you'll need for defence. In real history you'll see that civilizations that had a good military organisation usually were good roadbuilders as well.
It's nice that in this game you can draw so many lines to real history, isn't it?