Then there's the Wynyard Quarter, Auckland's waterfront and major road projects to the east and the west of the central city.
Gilmore is partly responsible for keeping the busy city humming while all this work going on. Downer has four major maintenance contracts with Auckland Council including the CBD. Potentially these contracts are for nine years, so there's a lot at stake.
Top of Gilmore's agenda is keeping people and cars moving. That in turn could lead to another risk. As an example he says a Queen St shop owner might look at the potential disruption and ask themselves if perhaps they should relocate to a suburban mall while the work is going on. Multiply that by thousands of businesses and there's a risk of the infrastructure upgrades causing more problems than they solve.
Gilmore says the scale of the capital infrastructure programme is unprecedented. In part it is driven by fast population growth in the city and Auckland's increased importance to the national economy.
There's also years of catching up to do. He says the council amalgamation makes it easier to address the city and regional infrastructure issues in a way that hasn't been possible in the past. Some important projects were left in the too-hard basket.
Pressure doesn't just come from internal sources. The World Economic Forum's Global Competitiveness Report, published early this year, found New Zealand moved five places up to being number 18 in the competitiveness rankings, going ahead of Australia for the first time. New Zealand scores well on many measures, but performs poorly on infrastructure quality, which the WEF sees as an impediment to growth.
Downer is looking to technology to ease the path. It is working with Ian Taylor's Animation Research to create an accurate three-dimensional model of the city as it stands today, then putting in the new structures to show what it will become. Gilmore says this will help planning and hold people to account after the event.
The technology was originally used for Animation Research's sports modelling. Gilmore says he saw one of the projects and noticed there was a 3D representation of the city in the background. This idea was picked up and used to create a more accurate high-definition representation of real buildings.
Downer plans to use the software to model Auckland's waterfront. It can work from a high level right down to showing how people and traffic will interact with the buildings and structures. The company plans to give this to the council to demonstrate its potential.
Technology comes in useful in other ways. Managing traffic flows around the city during the rebuild will need more than the traditional traffic cones and stop-go signs. Smarter data collection, so traffic systems operators can monitor flows in real time is a good starting point.
Most drivers have smartphones with GPS; it's possible to track these phones remotely to build up a clearer picture of where cars are across the entire road network. They can be used to see where traffic is flowing and where it is halted.
Problems can be identified immediately and drivers can be sent messages, via their phones or in-car navigation systems to route them around choke points. Traffic signals can be controlled to optimise flows based on the smartphone data. And roadside signs could be used to inform drivers of better routes to their destinations. Gilmore sees a lot more personalised trips for people.
A more radical approach might be to use the driverless car technology developed by Google and being trialled in the US. Gilmore says this could lead to convoys of cars speeding down the motorway closely behind one another. This could increase the efficiency of existing roads by packing fast-moving traffic more densely.
Either way, the focus needs to be on helping people make fast, safe journeys through the city while avoiding the natural choke points and the new ones created by the building programme.
