There are many variables influencing what Gate Type and Gate Material is best for each specific location. The process starts by determining the priority of a few criteria.
Gate Purpose - List the reasons for installing the gate.
Gate Location - Where will the gate be located?
Gate Usage - How will the gate be used, or not used?
Security Risk - Predict if and how the gate might be attacked.
Construction Cost - Estimate a budget for the project.
Local Conditions - Look for site-specific conditions that could affect the gate.
Once these questions have been answered then it is much easier to decide on a gate type and what materials are used in building it.
This steel is one of our favorite materials for building gates in remote locations. This steel has a very high content of Manganese, which makes the steel very resistant to attack with hacksaws, grinders and other abrasion attacks. This steel is work-hardened which means it gets stronger by about 100% when you bend or work the steel. This is the same material used in backhoe shovels and other heavy mining equipment. The steel is more expensive per pound than other steels, but often you use less steel so your overall cost can be competitive. This steel is a good choice for remote gates due to it's lighter weight in transporting. It is also a good candidate for gates that have a high risk of being attacked.
This steel is the common steel that you find in many angle iron and tubing gates. Since the steel is common, often the pricing can be very low. For higher security, these gates can be built of very large and heavy bars where the shear massiveness of the structure is a strong deterrent to attacks. When building heavy structures there will need to be truck access directly to the site. For higher security, concrete and other steel can be placed inside mild steel tubing. This makes the bars stronger and even offers some resistance to torch attacks. The concrete also keeps the bars from compressing and bending in a torqued pull or push attack.
This steel is less common in gates mainly due to cost. In harsh environments such as acidic or very wet applications, stainless steel is a good choice. It is often used in high use handles and railing since there is no rust residue left on users hands. This is not the case with Manganal or Mild steels.
Most projects use concrete for gate footers and other mounting forms. Concrete has a huge advantage in that it is cheap, formable, and very strong. A disadvantage of concrete is the weight of transport to a remote location. Concrete block walls in use with natural material backfills can also be used in horizontal mine adit closures.
This material has become very popular for sealing entrances and as fill material around culvert gates. A big advantage is that when it is mixed it expands about twice it's original size to form fit a void. The original material often comes in two-part liquid bags that are mixed and then poured. The hardened material is very tough, but must be backfilled with dirt to protect from UV degradation. Disadvantages of this material is it's high price, weight of transport, and that it could be burned. Also, once a site is capped and covered, often it's exact location can be lost and could be a risky site if there is heavy traffic or building over the site in the future. In many instances a grate or cupola gate over a large shaft might be a wiser solution.
Local rock and dirt are often used for gate backfill. An advantage is that it is probably onsite, and at no cost. Depending on equipment access, movement of the fill materials can be easy or difficult. In some applications the backfill may need compacted requiring appropriate equipment.