Easy solution:
Place.sqs
_obj1 = _this select 0
_obj2 = _this select 1
_ang = _this select 2
_dis = _this select 3
_h = _this select 4
_p=getpos _obj1
_d=getdir _obj1
_a=_d+_ang
_r=[(_p select 0)+_dis*sin _a,(_p select 1)+_dis*cos _a,(_p select 2)+_h]
? local _obj2 : _obj2 setpos _r
exit
Now execute this file with the following parameters:
[first_object,second_object,relative_angle,relative_distance,relative_height] exec "Place.sqs"
first_object: Is the object that is used as center, your roadway
second_object: Is the object that should be placed relative to the first, after spawning of course
relative_angle: For the right side use 90, for left use -90 or 270, or any other desired value
relative_distance: The distance object2 should have to object1
relative_height: The relative height, mostly 0
[road1,car7,90,2,0] exec "Place.sqs"
will place car7 to the right side of road1 in a distance of 2m and at the same height as road1...
If the calculation of the height of object1 brings up an unexpected value, play a bit with the input parameter until object2 shows up at the desired height.