This is a guest post by Jack Thompson. Jack is an engineer who has worked on civil construction sites in Canterbury, Waikato and Auckland. He writes in a personal capacity.
Why are the roadworks taking so long?
A previous guest post on Greater Auckland did an excellent job of breaking down why Temporary Traffic Management (TTM) is the way it is and the effort that goes into planning it. I won’t rehash that here. Instead I want to provide an insight into what goes on within the cones and fences. Why are the roadworks taking so long?
A common critique of roadworks is something along the lines of “When I drove by they weren’t doing anything, just a bunch of guys leaning on shovels.” This is based on seeing a worksite for maybe ten seconds out of an eight to twelve hour work day, hardly a statistically relevant sample size. Everyone on site has a specific role to play but that doesn’t mean they’re all occupied all the time. For example complex urban sites often have dedicated staff just for getting trucks in and out of site safely but when a truck isn’t there they just have to wait around.
There are seldom more resources on site than there need to be to get the job done. This is by design. Roadworks are generally done by contractors that are businesses, i.e. they’re trying to make a profit. It doesn’t make sense for them to have more staff, equipment or materials on site than necessary (although with staff there isn’t any choice because the whole industry is short-staffed.)
This operating model does introduce more ways for the job to be slowed down by something going wrong: A workmate might not be able to come to work because they’re sick. The digger might break down so you have to wait for someone to come and fix it or drop off a rental one. The pipes that got delivered might be defective and you have to wait for them to be replaced.
Why don’t clients force contractors to keep more resources on site to prevent shortages holding up the program? Because that would cost more and those costs would have to be passed on. Clients are generally service providers such as Auckland Transport, Watercare, Vector, Chorus and so forth. So increased costs will eventually be passed on to the public as taxpayers, ratepayers or bill payers.
What about improving worker productivity by investing in more training and new technology? Contractors already do this but the benefits don’t necessarily result in faster roadworks. They are more likely to result in working at the same rate with fewer staff. This enables contractors to win tenders by offering lower prices, which effectively passes on the cost savings to the client.
A Space-Time Continuum
With fixed productivity there are two ways of getting more done in a day: Using more space to allow more work steps to take place in parallel. Or using more time (working longer hours) to allow more work steps to take place in series. Usually roadworks can’t do either because they’re already operating at the limit of their regulatory constraints.
Let’s consider the example of laying a 110mm PVC duct all the way across a road. This looks like a standard house drainpipe except it’s usually colour-coded to whichever service is intended to be threaded through it later (orange for electricity, yellow for gas etc.) Existing services will need to be located first to avoid conflict. The trenchline will need to be marked out then the road surface cut using a concrete saw. A small excavator will be needed to dig out the trench. The duct will need to be laid in bedding sand then the trench backfilled. Finally the road surface will need to be restored using asphalt.
The fastest way to do this job is to close the whole road and dig the trench across in one hit. That way excavation, duct laying and backfilling can happen in parallel along the length of the trench. There’s no way AT (or other road controlling authority) will allow a road closure for such a minor job though. Depending on road width the work will have to be done in two or three sections using a contra-flow, one way system or stop-go setup. The lack of space will make the job take longer.
If the work site is on or near an arterial road then there will likely be work time restrictions on the traffic management plan, particularly during peak traffic. Another time constraint is that much of the equipment is noisy so its use at night will bother the neighbours and could result in an abatement notice from council noise control officers. This isn’t unreasonable, no-one wants a concrete saw (noise level exceeding 110dB) being used outside their house at 2am.
On a greenfields site this relatively simple job could be done in a day. In a city it could take two days if the crew is restricted to working in half of the road at once and only between 9am and 4pm. This loss of productivity can’t be blamed on any one thing but rather is the result of an accumulation of different constraints.
The Taniwha Beneath
Most roadworks require some kind of excavation. This carries the risk of there being something underground that the contractor hasn’t planned for. These ‘known unknowns’ include archeological finds, contaminated soils, unexpected ground conditions and underground services. It can be anticipated that they might be there but it’s impossible to be certain until the digging is finished.
Archeological finds usually result in all work having to stop until an archeologist has come in, recorded what’s there and confirmed it’s fine to continue digging. Most urban roads have been dug up so many times that this is relatively rare in the road corridor itself. On greenfields sites it’s more likely that something will turn up. Even finding something you think is an archeological discovery can create a lot of work.
Contaminated soils require extra care in handling them so that workers and the public aren’t exposed to them, which slows things down. This includes additional dust controls, personal protective equipment and encapsulated transport to special landfills. Long ago roads used to be built with coal tar, which is carcinogenic, so it’s not unheard of to dig this up. Other forms of contamination include heavy metals and asbestos.
Unexpected ground conditions are generally bad because they may require a change in methodology or even a change to the design, which could take weeks. Geotechnical investigations are done ahead of construction but they’re limited by sampling frequency and depth. This is evidenced by the problems caused with several large motorway projects in recent years. Look at the Waikato Expressway, SH2 Bayfair to Baypark upgrade, and the Christchurch Northern Corridor. Small projects run into similar problems but they don’t make the news.
The most troublesome things under urban roads are generally services (aka utilities). These include electricity cables, telecommunications cables, gas pipes, potable water pipes, stormwater pipes and wastewater pipes, plus all the abandoned services. There are enough challenges to working safely around services that it’s worth a whole blog post in itself. Suffice to say that it’s difficult, time consuming and getting it wrong can have serious consequences.
The construction industry in general faces a lot of problems (chronic staff shortages, cost inflation that far outpaces CPI, a cut-throat tendering environment pushing contractors to take on too much risk etc.) These underlying issues compound with the challenges of working in the road corridor.
In this environment any small problem has the potential to become a cascading failure. Consider a hypothetical situation where you’re the foreperson on a one-day job to install a service lateral (doesn’t matter which service) to a brownfields site in Auckland. It’s an arterial road so AT will only let you have the TTM in place between 9am and 4pm, which should be enough time. By the time the TTM is set up and the service locator has done their job it’s 10am. But they find a lot of unknown services so excavation has to be done very carefully, which slows things down. With hindsight you realise you should’ve got in a hydrovac truck. Then the excavator operator hits a previously unidentified pipe that was hidden under the other unknown services. This is a service strike so you have to stop work, get someone from head office to do an incident investigation and everyone will have to do a post-incident drug test. Now there won’t be enough time to complete the work before 4pm. You’ll have to cover the trench with steel plates and come back tomorrow. What was meant to be a one day job has become a two day job. The next job gets pushed back a day and so on.
This isn’t some dystopian worst-case scenario. Stuff like this is a daily occurrence around NZ. Seemingly everything that can go wrong, does go wrong at some stage. This is despite the best efforts of everyone involved.
It’s All Trade-Offs
I’ve spent plenty of time on site over the years, thinking about how we can do things better. The business imperatives, regulations and what’s actually underneath our streets aren’t factors that are going to change anytime soon. I have come to the conclusion that perhaps it is the best that we can hope for in the short term.
There is an explicit trade-off to be made between work duration and impact resulting in a continuum from short duration, high impact jobs to long duration, low impact jobs. At the former extreme is the principle on which much of the work on our rail network is done using weekends and public holidays for blocks of line. Most roadworks operate at the latter end due to the limitations already outlined.
In the end what level of disruption is considered acceptable to get a project done is not a decision for contractors. If a higher impact is considered a worthwhile price to pay for a shorter duration of roadworks then that needs to be negotiated between the client and the council (as regulators) after consulting the community who will be subject to the effects.