In civ4 you can't use roadds in enemy terittory. The commando promotion let you use them. That would be good to have such mechanism in elemental I think.

If by "integrated patrols," you mean something more-or-less automatic, I don't want that.

I'd like to be able to assign units to patrol either a specific roadway or a set of waypoints and I'd like to be able to build forts along isolated stretches of roadway. Having roadway security automated would remove a fun set of strategic decisions and possibly force a needless budget burden on players by making them pay for patrols on roads that are very unlikely to be attacked.

If you can spread caltrops and burn bridges down with your patrol, they'll do a hell of a lot to an invading army.  That's the logic for units not being able to use enemy roads in Civ, your civilization takes out infrastructure as they come.

Yes, it should. At least until you've been able to spend the time & resources to clean up afterwards.

a road is a road.  Your roads aren't giving your enemies the economic bonuses that they are giving  you.  So your criteria is met.

It could be done in the form of spawning bandits and raiders who use your roads to prey on caravans and traveling citizens.

This is an ellegant solution and should be perfectly sufficient.  So yes, roads give the invader an advantage, but you a greater advantage.  What's more, if the enemy uses your roads, then they are essentially having to pay for it.  I might give them slightly smaller benefit of movement than the native soldiers would gain on their roads.  You might also add magic roads later that disappear or turn to rubble when foes are on the march.

Well roads is a road, or a trail if you perfer. There shouldnt be no rules against it, we all should be able to use it but not pillage it. If there a bridge, you can destroy it if possible, but only with the right tool not by hackin it with a sword.

I think it's far more important to simulate supply lines than to do road use. Scorched Earth is fine but I'd rather have the developers concentrate in other areas.

EDIT: Not that roads have nothing to do with supply lines... but I'd rather have roads be a part of supply lines rather than supply lines be a part of roads.

First in CivIV I found it stupid that enemies moved slower on hostile roads since liek someone else said a road is a road.

Things such as needing travel papers are nice and will slow down people pass throught your lands legaly. But if the dude is comming to kill you that won't slow him down.

Control of roads can and should only come from actual troops on the ground. This could lead to the creation of a road outpost: an outpost would be a small fortification you can build on a road after "X" distance from near city or on intersections. These could ahve a sone of influence that would slow down enemy movement around them. (like in CivIV you could only move 1 space around a hostile city even if you could normaly move 10 spaces.)

Traps and magical speels sound ilogical, and out of the EWoM theme form what I can fell form it so far.

What I coudl see magic playing a function with roads is that you road is enchanted to provide you with vision of everything that happens on it. So if your enemy uses your road you will see him. This could also add int eh function to steal/take roads as one own with you own magic to dispeel the enemy's vision magic and replacing it with your own. (That is for areas outside of your zones of influence.)

heh dont think those traveling papers will stick, anyone can make those, just need an artist to forge them.

Yeah keeping it simple is better. I'll clear out idea for booth road magic vision and road outpost.

Road Magic Vision:
-It gives vision of the tiles the road is built on. So any unit that steps on to your road will be visable. Quite simple realy, that that you can add this: Proximaty warning, for the tiles adjacent to your road you can get a warning icon, a warning icon would be identical for all units that it might be revealing teh presence of. So you know somethign si ther ebut you do not know what it is until it steps on your road.
-Roads should be "capturable", basicly with teh use of magic of your sovering (or heros) you can uncast the magic vision speel of a player ona  road and replace it with you own, hence making you the now proud owner of said road. To be able to captuer a road you should have a zone of influence of your own touching the road. (IE, you can't start stealing roads in the heartland of your enemy's terrytory. You'll have to work your way in.)

Outpost: (inspiered from Starbase in Sins and the Ruined tower in LoTR where Frodo got stabed by the Nazgul)
-Outpost can only be built on roads (what do you expect). They can be upgrade by 2 way that I can imagine, first more traditional is a build upgrade your puchase for it that takes time to build and increases defence and so on. Second, more original way is to have it being reinforced with troops, when reinforcing the troops now become part of the outpost (you lose control of them) and the type of troops determines what type of upgrade the outpost gains. (type of upgrade is left to imagination and debate)
-Outpost have a small 360 zone of influence aroudn them that will slowdown any hostile forces traveling throught it. This zone is uncontestable (EI you can claim teh tiles unlest you conquer the outpost) and this zone can not contest teh zone of influence of other players, you will need to conquer the enemies influence via teh otehr means the game has. (Ei you can not build and outpost next to enemy teritory to steal the teritory. It's not a terrytory stealer.)
-Outpost should provide protection for your road vision magic for around double the distance of the zone of influence. (So your roads cannot be stolen right up to your front door.
-Outpost strenght? Dunno how strong these should be but they should not stand up to armies, maybe only small gangs and such. (IE much weakear then the SBs of SINS in tearm of firepower and defence)