Two of Guardian's shield options are: Modular boxes or trench shields. Each with their different strengths.

Weigh up your options here

Keep reading below to find out more details on the differences.

Modular Boxes

Weight

Lightweight, individual panels able to be lifted by hand, but a machine is required to lift and move assembled shields.

Setup

Take longer to assemble as they are made up of multiple panels with joiners.

Best Used For

Trenches with obstructions like pipes or cables in them, or for manholes.

Transport

Easy to load and transport on Utes or small trailers when disassembled. Truck or heavy trailer needed if assembled.

Flexibility

Can be configured as a box or with an opening for pipes and cables ect.

Cost

Higher initial investment.

Strength

Typically, the longer the panel, the lower the kPa rating. Eg the 1.5m has a 74kPa rating. The 1.8m has a 57kPa rating. The 2.4m has a 44kPa rating. The 3m has a 26kPa rating.

Trench Shields

Weight

The smallest panels are a 2-man lift, and the rest of them can only able to be lifted by machine.

Setup

Fast to assemble as all shields are made up of just 2 panels and 4 struts.

Best Used For

When installing larger diameter pipes, as more clearance, longer piping distances as faster to move and more robust.

Transport

Small size easy to load on Utes, larger sizes need a truck or a heavy trailer.

Flexibility

Fixed size and shape, though most can be made into a box and smaller ones put on their side etc.

Cost

Lower upfront costs for smaller shields, but as the size gets bigger, the cost increases.

Strength

Typically, the longer the panel, the lower the kPa rating; however, different styles are available with higher ratings. Our small 2.4m shield has a 20-50 kPa depending on strut placement. The 3.5m has a 43kPa rating. The 5m has a 55kPa rating. The 7.2m has a 36kPa rating.

Weight – Man vs Machine

Many of the certified-compliant Guardian modular trench boxes have the advantage of being lightweight enough to be made without machines, and usually just two people. Then they can be installed into the trench by a machine.

In comparison, only the smallest 2.4m x 1.2m trench shields can be put together by hand; anything bigger requires machinery to lift them into place. They’re ideal if you have the space, the heavy gear, and need a bigger trench.

Set Up – time vs capability

Modular trench boxes are easily reconfigured to form a 2-sided shield, a 3-sided trench box, or a completely enclosed manhole. Though they do take a bit longer to assemble than a trench shield, as each panel must be put into place and stacked to build the required configuration.

Watch this video to learn how to make a Modular trench shield: https://www.transquip.co.nz/blog/Learn-How-To-Make-the-Guardian-Modular-Trench-Shields-video

The standard trench shield is fast to make due to the simplicity of the design, with just two panels on each side and join with 4 struts. Job done!

Watch this video to learn how to make a small trench shield: https://www.transquip.co.nz/blog/Learn-how-easy-it-is-to-make-up-a-2301-Lightweight-Aluminum-Trench-Shields

The larger shields take a little longer than the small shields, as a machine must be used to get the panels in place. Watch this video to learn how to make a small trench shield: https://www.transquip.co.nz/blog/Watch-How-to-Make-a-Large-Aluminium-Trench-Shield-Video

Best Use – Shield vs Box

Guardian Modular panel wall thickness is 50mm, which keeps excavations to a minimum and reduces time and costs on backfilling and restoration. They’re the right fit for tight spaces and the smaller sites contractors often operate in.

Shields are suited for medium to larger scale projects installing larger diameter pipes, as there is more clearance and space to work within the shield, and it is faster to move one large shield than multiple small ones. You can rely on these large trench shields to keep workers safe (the number one priority!) and the job moving along smoothly.

Transport – Weight vs Time

Modular boxes and trench shields differ notably in terms of transport and loading requirements. Modular boxes can be disassembled into smaller, manageable components, allowing them to be easily loaded onto small trailers, making them ideal for sites with limited access or smaller transport fleets. However, once assembled, they become bulky and heavy, necessitating transport by a flat-deck truck or large trailer.

Trench shields, on the other hand, only the small trench shield can be loaded onto Utes or small trailers, while all medium to large sizes require a truck or heavy-duty trailer for transport, regardless of being assembled or not. This makes trench shields less flexible for transport compared to modular boxes, which offer greater adaptability depending on how they are packed.

Flexibility – Fit for Purpose

The different ways a modular can be configured:

Adjustable struts – these are mostly used on the shields not modular boxes. The struts (or spreader bars) mean the system will easily shore different-sized trenches, maintaining supportive positive pressure on the trench walls. The adjustable struts come in 0.6m up to 2.9m. See our full range online HERE.

NOTE: Whether it’s a shield or a 3-sided box with struts, never lift using the struts. They're not designed for it, so they can bend and then get stuck, so you won’t be able to adjust them again.

The different ways a large shield can be configured:

The different ways a small shield can be configured:

Cost - Time vs Size

Cost for both a modular and standard shield depends on the size, kPa, weight and length of hire. The smaller the modular box or shield, the cheaper. The higher the kPa, the more expensive. The heavier the box or shield, the more expensive to transport, as the weight increases, the freight cost. You need a truck instead of a ute or trailer if the box or shield is very large. The longer you want to hire, the cheaper the hire rate.

Buying our modular boxes is a larger upfront investment as they are more expensive to manufacture due to their complexity. The cost of a small shield is a smaller upfront investment; however, the larger the shield, the more expensive they are, especially if it’s one of our super shields that have a higher kPa rating.

Strength

Different sizes and configurations have varying ratings.

Shield kPa (strength) can increase with extra struts or a stronger design like a super shield (however, this does increase weight).

If it's a bigger job, for example, a job requiring a higher strength-to-weight ratio, check out the Guardian Large Aluminium Trench Shields.

Watch this video to see what FAQ’s we have on these shields: https://www.transquip.co.nz/blog/This-Video-Answers-the-Most-Common-FAQs-About-Large-Aluminium-Trench-Shields

Any Shield or box should only be used if a certified geotechnical engineer has assessed the trench and confirmed that the ground kPa ratings do NOT exceed the modular boxes or shield kPa ratings.

What’s best for you?

If you have any questions at all about what you need to get the job done safely, just ask us - our trench (and people) protection experts are ready to help. Or jump on the WorkSafe site HERE.

Or, for a real-life example of Guardian shoring on site, click HERE.

Disclaimer: While Guardian strives to give accurate, up-to-date advice regarding our products, it is your responsibility to ensure you meet legal requirements, rules and regulations BEFORE putting shields in the ground.