Infrastructure Report: Communications restored but not back to normal

Chorus staff attempt to restore fibre optic cable to Hawke’s Bay and Gisborne where a bridge was washed away by Cyclone Gabrielle. Photo / George Heard

Voice and data communications links are restored in the parts of the country that took the brunt of Cyclone Gabrielle and the other extreme weather events earlier this year.

People in Hawke’s Bay, Tairawhiti and the Coromandel can make voice calls and use the internet again.

Yet “restored” does not mean networks are back to normal.

Paul Brislen, who heads the Telecommunications Forum (TCF), says in places backhaul fibre remains strung over the top of trees where it was laid in the days immediately after the cyclone. It may stay there for weeks.

Think of backhaul fibre as the telecommunications equivalent of state highways. It is the main national network used to connect regions, towns and other areas to each other and back to the main hubs in Auckland. It connects the local ultra-fast broadband (UFB) fibre networks used to deliver broadband to homes and businesses. Backhaul also connects mobile towers to their network and, for now, it continues to connect copper lines to the rest of the telephone network.

For the most part, the local UFB networks, mobile connections and fixed wireless broadband suffered little damage in the cyclone.

Telecommunications Forum head Paul Brislen says true resilience will cost "an absolutely astonishing amount of money".

Says Brislen: “Only two mobile towers were damaged. The real damage to the network was a fibre cut. In the case of backhaul fibre, that was traumatic. Also, the electricity was cut off. That meant we lost 600 mobile towers for a large part of a week.”

The problem with the backhaul fibre network is that it follows the road network and, where necessary, crosses rivers strung underneath road bridges along with electricity cables and water pipes. Most of the damage to the backhaul fibre was in places where the road or bridge was damaged. Brislen says somewhere between 70 to 80 bridges were damaged, taking out fibre with them.

“We’ve still got cases where Waka Kotahi is still sorting out what it will do with the road,” says Brislen.

“We can’t do anything until the road is sorted out, which is why fibre is laid over trees. We’re not terribly resilient at this point is the nicest way of putting it. The network is operational. It will continue working as long as there’s no more heavy rain and as long as the ground doesn’t slide further.”

Fixing this and building in the necessary network resilience for what looks set to a future where there is more extreme weather requires radical rethinking for the entire sector. It needs government intervention and fresh legislation.

Brislen says one possibility would be to move all the backhaul fibre underground, which would be a massive and expensive undertaking.

“The easiest thing for Chorus to do at the moment is to move the fibre river crossings a few hundred metres away from bridges and put the cables on poles high enough to lift the fibre out of the way of flood damage. It’s possible, but there are land access and consent issues to deal with.

“Another option is to move the fibre away from roads and, maybe, follow the electricity pylons.

The problem is that the electricity companies only have access to the land to run electricity cables, nothing else. This would require a legislative change and negotiation over land access.”

You might think one sure way to build more resilience into the fibre backhaul network is to increase the number of routes between regions. Before Gabrielle, conventional thinking said you might need a handful of routes into Hawke’s Bay. After all, says conventional thinking, they can’t all go out at the same time.

Brislen adds: “For a region of that size you’d normally expect two lines would be enough, three would provide resilience. We had eight or nine lines into the region, all of them were cut because of the sheer scale of the event.”

Building more lines would add to costs without necessarily solving anything. Hence the need to rethink resilience.

This brings us back to putting fibre underground, away from roads or even building a submarine cable that runs around the coast.

Line-of-sight microwave links don’t have the capacity and, anyway, need to be carefully calibrated. Earthquakes knock them out of alignment.

Many people believe satellites are a potential answer. They certainly played a role in the immediate aftermath of Cyclone Gabrielle, but they are just as dependent on electricity and need terrestrial networks of ground stations to connect users to the internet. If the power goes out in a storm, a residential or business satellite connection will only operate as long as any batteries or generators last.

There is another problem with satellites that anyone who has used Sky TV will be familiar with: rain fade. In a heavy downpour a satellite’s data speed, which is already lower than the speed on a fibre network, will drop. Connections fade in and out. Satellites are, at best, a back-up option.

New Zealand is not the only country facing telecommunications infrastructure problems. Australia’s network has contended with widespread bushfires and severe flooding in recent years. Japan faces similar seismic and tropical cyclone risks. There are lessons from both countries’ experiences that apply here.

Brislen says whatever we do, it will come at a tremendous cost: “If you want true resilience, you’re going to need to pay an absolutely astonishing amount of money.”

We can expect to see large phone and broadband bills as telecommunications companies harden their networks for the new normal.