Trench

In civil engineering, trenches are often created to install underground utilities such as gas, water, power and communication lines.

In archaeology, the "trench method" is used for searching and excavating ancient ruins or to dig into strata of sedimented material.

The advantages of utility tunnels are the reduction of maintenance manholes, one-time relocation, and less excavation and repair, compared with separate cable ducts for each service.

Underground power lines, whether in common or separate channels, prevent downed utility cables from blocking roads, thus speeding emergency access after natural disasters such as earthquakes, hurricanes, and tsunamis.

However, these large, permanent trenches are significant barriers to other forms of travel, and often become de facto boundaries between neighborhoods or other spaces.

In the pre-firearm era, they were mainly a type of hindrance to an attacker of a fortified location, such as the moat around a castle (this is technically called a ditch).

The advantage of this method is that it destroys only a small part of the site (those areas where the trenches, often arranged in a grid pattern, are located).

The risks include falling, injury from cave-in (wall collapse), inability to escape the trench, drowning and asphyxiation.