Tristan da Cunha Development News

Successful rebuilding of a section of Top Road in two days

Report and photos from PWD Director Mike Wolfenden

PWD are pleased to report that one of the worst stretches of the “Top Road” in the Tristan Settlement has been dug up, filled, compacted and concreted with wire mesh reinforcement. The Island uses reinforcement in all the roads now. One of the reasons for the some of the poor stretches of road is the thickness of the concrete and no reinforcement. PWD General under Jonathan Repetto has managed to complete this stretch of road in the fast time of two days, on 18th and 19th January 2016. The task included digging out the old road, building all shuttering, putting on a sub layer of grit which is compacted and tamped smooth. The concrete was then laid over the wire mesh and ‘floated’ to produce a smooth surface. It will have to cure for minimum of 7 to 10 days before it can be driven on, but should last over 50 years without any problems. This island never has snow and frost, and lots of rain during curing makes the concrete harder and prevents cracking. On Tristan rain is as reliable as the sun coming up!

Statistics: The repaired stretch is 50 metres long and 3.3 m wide with a depth of 6 inches. That sits on the compacted subsoil which was laid also at 6 inches over the sub soil. This equates to 25m 3 of concrete weighing 45 tonnes. The sand is island rain washed, black rock sand and the fill is from the nearby Hottentot Gulch.

The team used a mix of: 1 cement, 2 Sand and 3 chippings, which is a good guide to making long lasting concrete and is recommended by Barry Davies our Clerk of Works.

The digging out was by Duncan Lavarello, who has been involved in a lot of track maintenance especially on emergency gulch work when the road to the Patches is swept away This road is crucial for access to farming activities at the Patches, eg care of the sheep, cows and potatoes. The Team has to open up the roads after big storms and even has emergency cover with JCB’s over the holidays in order to keep the island mobile.

Mike Wolfenden, was able to release materials left over as surplus from former projects, which enabled the team to use sufficient cement and good quality chippings to make long lasting concrete.