Do you shudder each time you hear the screech of brakes, then the long pause before the bang, as a car speeds through an intersection and crashes? You hold your breath, hoping the people are ok and they can walk away. 

This is why many budget-minded road safety professionals are turning to compact roundabouts to transform notorious intersections on their road network. Like you, they are eager to remove the anxiety and make sure their people stay safe.  

They may be small, but compact roundabouts pack a punch by improving traffic flow, forcing people to slow down – deflecting bad decisions with some seriously good cost-benefits. 

This article takes a look at compact roundabouts, their safety benefits, material types, and costs, as well as some of their shortcomings. By the end of the article, you will have a better idea of how these roundabouts can be used as a treatment to transform unsafe intersections without blowing your budget.

What are compact roundabouts? 

We see roundabouts everywhere in urban and rural environments. Put simply they are different-sized circles in the middle of an intersection that vehicles drive around to help move traffic safely. All over the world, they are recognised as a key safety treatment for intersections and no doubt you’ve driven around one before.  

A standard ‘roundabout’ needs to comply with Austroads Guide to Design whereas a compact roundabout (or even smaller, mini roundabout) is a smaller structure that works in the same way. Usually a single lane, with a smaller central island, they are a very cost-effective way to transform unsafe intersections. 

(Want to dive deeper into stats? This fact sheet gives you more detail about how they differ from standard roundabouts, and a neat video taking you through design considerations!) 

VIDEO: Compact Roundabouts 

Like all roundabouts, compact roundabouts mitigate risk and improve safety by reducing conflict points to avoid dangerous head-on and side-impact collisions, reducing vehicle speeds, and reducing the likelihood and severity of crashes.   

Why are compact roundabouts so cost-effective? 

Generally, compact roundabouts save money compared with major roundabouts because they take up less space and can often be installed within the existing intersection footprint. The cost savings, both time and money, are significant. Add to this a fast installation time, some in a few hours, and you can start to realise their investment value. 

From a design perspective, the central island size can be adapted to accommodate different vehicle types, such as heavy or long vehicles, ensuring traffic flow is efficient and safe.  

There is also a range of materials to suit most budgets, which we will explore later. 

Good design means good results 

Getting the design right is critical and there are a few considerations you need to make before deciding what roundabout will suit your needs. If you love a good tick list, you can use this really practical fact sheet  to help educate your thinking and answer design questions like: 

• What will the splitter islands look like? 
• What size central island will you need? 
• Do you need speed platforms on approach? 
• Are heavy vehicles able to navigate the turn? 
• What path will vehicles take to manage speed? 

 

Images: Compact rubber roundabout with concrete splitters (left) and mini rubber roundabout with speed bumps 

A collaborative approach to road safety 

Fast safety is impactful, but have you thought about the concept that road safety is a shared responsibility? The idea is that whether you’re a cyclist, engineer, taxi driver or safety lobbyist it’s the collective effort that is making significant shifts in how we do safety in New Zealand. 

Community support can make or break a project so it’s no surprise that early engagement is critical. This is not just to get your project over the line and improve safety, but to seek feedback on what works for people using it. You can do this through public meetings, online surveys, social media, door knocking, focus groups and community workshops, targeted mailouts, neighbourhood information sessions, or even creating a drop-in centre. Find whatever way works to reach the most people so that you hear diverse voices throughout your planning process.  

If this piques your interest, this article has some helpful insights into community involvement in road safety, including the impact and implementation of this approach. It’s well worth a look. 

Intersection safety: How effective are roundabouts?

No one expects a crash or thinks it will happen to them, especially the most careful and responsible drivers. When you or someone you know makes a mistake, no one wants to die or face serious harm.  

A New Zealand study shows that whether you are driving, walking or riding a bike, you are more likely to crash at an intersection than any other part of the road network. 

Roundabouts are widely considered one of the best safety treatments for intersections because of the way they help people and manage speed: 

1. They simplify decision-making, help reduce errors and significantly improve safety as traffic flows in only one direction, with no priority, making it easier to decide when to enter the intersection.
2. Everyone slows down when approaching the roundabout improving safety and alertness. People are always prepared to slow or stop.
3. AND…they significantly reduce deaths and serious injuries – virtually eliminating deadly head-on or side-impact crashes. 

Image: rubber mini roundabout with painted circle and pedestrian refuge on approach. 

Safety benefits: what do roundabouts reduce? 

So far we’ve seen that roundabouts reduce speed, conflict points, driver errors and deadly crash types.

Even if you are not a numbers person it is impressive to know that roundabouts dramatically reduce deaths and serious injuries by at least 60%. A study in Australia  reviewed 40 fully mountable, mini roundabouts installed in Victoria. Monitoring showed crashes reduced by almost 80% with zero fatalities.  

That’s a massive safety improvement and acknowledges that human mistakes are inevitable, as crashes will still happen. But roundabouts are designed to mitigate the consequences of those mistakes by reducing the severity of injuries. 

Given the impressive safety benefits of roundabouts, you also need to know what types of compact and mini roundabouts to consider for your project.

Building for your budget 

As with all infrastructure projects, you need to know your project cost, safety objectives, and future maintenance. You must choose infrastructure that stands up to traffic types and volumes and achieves what your project is setting out to do.  

This is not an exhaustive list, but start by asking these ten questions when investigating or designing a roundabout: 

1. What is the location? 
2. What is the risk I’m addressing?
3. What is your project trying to achieve?
4. What size roundabout do I need for the intersection?
5. What vehicle types, and how many, travel through each day?
6. Is it a high pedestrian or cyclist area?
7. What community buildings or businesses are in the area?
8. Will I need additional safety measures like raised platforms or traffic islands?
9. Do I have the resources to install it?
10. What temporary traffic management will I need? 

When you’ve got an idea of these answers, you’re in a better position to consider some of the different types of mini or compact roundabouts available to improve safety. 

Roundabouts: Types and cost 

So you’ve reviewed your project variables like location, users, traffic types and volumes, specific site conditions, labour and traffic management. Now deciding what to build.  

A major roundabout is likely to be in the millions, with possible land aquisitions, site preparation works, traffic management and labour. This is a completely different scenario compared to transforming an urban cross-intersection with a compact roundabout, which can be done for between $30,000 (for rubber) to several hundred thousand (for concrete).  If that’s out of your budget or needs, a mini roundabout might set you back as little as $10,000 or even less, a painted roundabout for $5,000 complete with signs!   

As said earlier, you need to match the treatment with the traffic and install it correctly if you want it to last. If you are unsure at this point, one of our expert team can guide you through these questions. 

Keeping in mind the cost ranges of roundabouts, you might be wondering: what are the advantages and disadvantages of using different materials to construct roundabouts? 

Material choices: Rubber, concrete, asphalt and paint 

All compact roundabouts offer the same safety benefits if they are designed well but there are pros and cons of using either rubber, concrete, asphalt or paint to install it. If you want more detail about construction materials, you can find it in this article: Choosing the best road safety material: Rubber, concrete or asphalt. 

Below is an overview of the types of installations best suited for each material.  

Rubber

Rubber modular roundabouts are ideal for trials, offer fast overnight installation and opportunities for community input. Modules can be configured to any size intersection and if damaged, are easily replaced.
Their temporary nature means they are perfect for trial installations that allow genuine community consultation, and provide a pathway to decide what permanent infrastructure should be built

Concrete 

If you want a permanent roundabout then concrete is a good option for a long-term project. It is perfect for heavy vehicles or high-volume traffic due to its great durability and low maintenance.  

Asphalt 

If you have a limited budget then asphalt is a good choice. It will need painting after curing so can add to traffic management costs. It is ideal for low-traffic areas and can be installed as a semi-permanent structure in higher-traffic volumes areas with heavy vehicles 

Paint 

I know what you’re thinking: How do you build a roundabout out of paint? True, a painted roundabout is simply a circle painted in the centre of the intersection. However a study has shown they are often used very effectively in low-traffic areas or as temporary solutions in urban environments and function just as well as rubber or concrete in some places. If a low budget is your number one priority, get painting! 

It’s Time to Get Your Project Started 

Only you can answer the question of whether a roundabout is right for your intersection, but hopefully you’ve learned that it is wise to consider the significant safety benefits they can offer. 

We’ve seen that mini and compact roundabouts offer a superior intersection treatment that slows traffic down, simplifies decision making and enables monitoring of the location and function to ensure safety is improved.  

Each project needs its analysis, but it is worth considering whether they might just be the cost-effective, adaptable tool you need in your road safety kit. 

To transform your road network with confidence, get in touch with our team of experts and we can guide you through the process.  

 

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