By Bryan Ferguson, engineering officer Transportation, Taupo District Council.
It is standard industry practice with chip reseal to remove all retroreflective RRPMs (Cats Eyes) and non-retroreflective raised pavement markers, RPMs, prior to a reseal, or maintenance crack seal/second coat patch seal.
These are normally replaced along with the road markings once the completed site is swept of loose chip.
As a less costly and easier method (when the reseal will be using a void fill and small sized chip – such as Grade 5 or 6) you can save the RRPMs by simply placing a purpose made cover over them to protect from bitumen spray. These covers are removed after the chip has been spread, saving the cost and time of installing replacement RRPMs.
These covers are made from plastic or wastepaper pulped up and moulded to the shape of an RRPM and fits over it with double side tape fixed to the top.
In 2019 I worked with Mike Plowright of Plowright Industries in Tokoroa to produce RRPM covers from wastepaper.
When I was managing road maintenance contracts in the Taupo area I used to get plastic Rayolite covers for maintenance crack sealing and second coats. Not all RRPMs could be covered due to the chip size to be used or their condition, but when we could it saved having to send someone out to replace one or two RRPMs which could turn out to be an expensive exercise.
I believe these covers are no longer available here, but my path to developing the wastepaper cover idea came after watching the wasteful removal of sometimes recently installed or RRPMs in good condition. Using a cover made from wastepaper seemed a good move away from plastic. In fact, the idea came to me while eating a hamburger that was packaged in a square container made from recycled paper.
Mike Plowright is a one-man band that produces mainly packaging and plant pots from old newspapers. When I approached him with my idea, he made up a mould producing several hundred covers which both the Rotorua and Auckland HEB sealing crews have used successfully.
The cover comes with double sided tape underneath, which you peel off and adhere it to the top of the RRPM. To remove, you simply flick the cover off with a square mouth shovel exposing the RRPM. I can’t recall the exact price, but I think Mike was charging $0.45 per cover. And bear in mind I am used to paying a contractor up to $18 to replace an RRPM.
We used these covers on reseal sites of over a one kilometre, with the bonus of the site being delineated down the centreline for the couple of days before the site was swept and road marked.
The trick was getting the new centreline painted between the RRPMs. The position of the marking tends to creep and get paint sprayed over the RRPMs.
More information: www.plowrightindustries.co.nz.