Accelerated Construction: embracing the new normal 

As chaotic as recent weeks have been, they’ve also shown us the things we thought were impossible aren’t. Dave Idle, Technical Principal Bridges & Civil Structures, looks at opportunities for construction post the Covid-19 lockdown.

Embracing the new normal, what if we can?

At the time of writing this our motorways and roads have never been quieter. People are breaking the boredom of self-isolation by taking to empty streets on foot and bikes (if my neighbourhood is anything to go by) and observing the potential of urban environments not dominated by commuter traffic.

KiwiRail has noticed this reduction in traffic volumes around Auckland and has worked with Auckland Transport to replace four kilometres of rail on the Eastern Line which, under normal circumstances would have taken much longer. Amazing things can be achieved with clear access to project sites, without the usual restrictions due to traffic. What if more infrastructure projects could be delivered like this? This is where Accelerated Construction (AC) could be a game-changer, particularly for transport infrastructure projects. AC uses advanced planning techniques, collaboration and innovative design to significantly reduce design and construction periods, while reducing construction costs and increasing construction quality. WSP has successfully used it in New Zealand on bridges and transport projects.

So, what are the benefits of AC and why do they suit post Covid19 construction projects recovery?

A shorter construction time will, in general, have a lower impact both socially, environmentally and economically. Our infrastructure funding process in NZ should mean these proposed projects demonstrate value for money and have a sound business case, but they often take a long time before the benefits are seen. Through the collaboration embedded in AC we get these projects on the ground faster, open to users earlier and are an economic stimulus throughout. So why isn’t it used more regularly? AC seems to provide lots of benefits, but taking it mainstream requires us to look at our current processes and embed AC thinking throughout. Because AC impacts every stage of a project, from planning and design, through to procurement and construction, with key elements in each stage that enable the next phase, it needs to be embedded from day one.

Many design and planning methods readily fit into the AC philosophy. Using digital 3D (or 4D) models throughout a project lifecycle helps with collaboration and development of automation is improving speed in design and construction processes. The Infrastructure Project of the Future, as outlined by my colleague John Welford has links to AC too. It’s the banner which sits above all the tools that are ultimately trying to achieve goals of delivering high quality, faster projects, with minimal impact.

One perception is that because AC is shorter (and sometimes higher impact on traffic) it is a nightmare for the community, but this isn’t true. The replacement of Mt Wellington Highway road over rail bridge, which is adjacent to an SH1 on ramp and approximately half a kilometre from Sylvia Park Shopping Centre had no complaints to the client hotline throughout construction.

Admittedly there are barriers that are hindering a more widespread adoption. AC requires more detailed planning because the work is being carried out within compressed timeframes, which can have a higher impact for a short period of time. To achieve this, a good understanding of constructability at an early stage and a collaborative environment between client, designer and constructor is necessary. This collaboration is already evident in the current system, with the common use of collaborative contract models. More recently has been the move to hybrid alliances. WSP is currently part of two and this alliance model aligns well with AC principles, and the value process within those contracts is a perfect proving ground for AC. Continuing to improve and value the benefits of AC early in the project lifecycle will leave opportunity to incorporate it in more projects.

One of the biggest challenges is a change in the construction and estimation space.  Projects are typically priced on materials quantities and programmed based on resource availability. This means construction programmes are designed around keeping people busy for as long as possible, rather than looking at what activities can be run in parallel and 24hr working to assess people requirements. This fundamental shift could offer large savings. Preliminary and General (P&G) typically runs at 20-25% for most construction projects. In urban areas, temporary traffic management (TTM) can be a similar order of magnitude. Applying AC, and resourcing to meet the opportunity provided, would result in significant time and cost savings. A traditional urban bridge widening or replacement might take four months, but we’ve replaced them in four weeks. This would have resulted in at least halving the P&G and TTM, so 20%+ cost savings. If we can do this, the benefits are huge. Shorter timeframes mean less extended periods of disruption which is ideal for users of major urban roads, light rail or airports. Fundamentally, it also realises the benefits of the financial investment earlier.

In the wake of the Covid19 lockdown we have the opportunity to embrace the paradigm shift required to adopt an AC philosophy.

About :
Dave Idle is a passionate and experienced project leader and structural engineer. He is particularly interested in the benefits of collaboration between designers, planners and constructors. He has been a key member of several collaborative contract transport infrastructure projects around NZ. Connect with Dave on LinkedIn.


As part of the Auckland Electrification Project, KiwiRail commissioned WSP to design the replacement of five bridges. Innovative solutions were developed using Accelerated Bridge Construction (ABC) principles to minimise the bridge construction periods and associated disruption of both road and rail networks.



Reduced construction time, minimising traffic disruptions, reduced life cycle costs and improved construction quality and safety are potential benefits of Accelerated Construction (AC). The philosophy is to minimise the on site construction time by maximising the use of precast/off site manufactured elements.



Accelerated Construction (AC) uses advanced planning techniques and innovative design to significantly reduce design and construction periods, while reducing construction costs and increasing construction quality.
Find out what else should be considered.