This type of terrain, which includes walls, fences, tank traps, barbed wire, etc., is usually mounted on a base which is about 1" wide and approximately 4" to 6" long. It is a particularly useful type of terrain because it are easy to transport and store a couple of dozen pieces in something the size of a shoe box.
Linear obstacles can also provide a wide range of challenges on the gaming table. For example, something like a barbed wire or chain link fence hinders the movement of troops while providing them with no cover. On the other hand, a low wall provides cover but does not impede movement (because troops can clamber over it). A taller wall will block their line of sight completely and hinder, if not completely prevent, movement. The effects on vehicles can also be very interesting: the barbed wire fence that stops troop movement will not hinder a tank, however a row of tank traps will stop a tank while allowing troops to move freely (and may also provide them with cover).
A final bonus of linear obstacles is that there are dozens of ways to make them, many of which are ideal projects for beginners.
We've created a gallery album to inspire you with ideas for linear terrain and provide a link below, along with links to some other useful articles. Before we get to that however, and before you set about making some of your own, it is worth making a note of the following tips from Hank Cowdog:
Narrowing or rounding the ends of the bases allows the obstacles to be arranged in shapes other than straight lines and have the ends line up well. You could for example arrange them to create an enclosed compound.
If you extend fencing beyond the outside poles i.e. to the very edge of the base, multiple sections can be set up next to each other with no gaps.
Make more pieces than you think you'll need - it is easy to make "one more" once you are making more than a couple. I'd suggest 6-8 of each piece.
Make some special pieces for openings (doors, drivegates, destroyed sections, etc.). This expands the gameplay options when these sections are included.
The Linear Obstacle Gallery Album - lots of inspiration for linear obstacles.
Barbed Wire - A variety of methods for making barbed wire.
Mesh Fencing - Gary James tells us how he makes mesh fencing.
Walls - Tom Jagiello tells us how he makes walls.