Eight per cent of men and 0.5 per cent of women have a colour vision deficiency, which means they struggle to discriminate red from green, yellow and orange. What does that mean for navigating in the backcountry?
“Where are you going?”
I ask my partner in front, on his first experience of tramping in the New Zealand backcountry, as he veers off the barely discernible track.
He looks at me like I’m crazy and points to the faint outline of what could be a track meandering into the undergrowth. “I’m following the trail,” he says.
“No, the trail is straight ahead. Can’t you see the orange triangle?”
“What orange triangle?”
I point to the bright orange three-sided marker nailed to a tree, stark against the green foliage. “That one right there, 20m away, on the tree. About head height.”
He squints in the direction I am pointing, confusion on his face. “No.”
He walks on another 5m.
“Can you see it now?”
He shakes his head and goes on. A few metres from the marker, he stops and points with vexation. “Now I can see it! Whose stupid idea was it to make it orange?”
My partner, Mark Evans, is colour-blind. He mixes up blue with black, green with red and brown, pink with grey. He also has trouble seeing triangular orange track markers.
Evans is one of the eight per cent of men and 0.5 per cent of women who have a colour vision deficiency due to an absence of or impaired sensitivity to one or more of a cell type in the eye, known as cones. There are several types of colour-blindness, but the most common is red/green colour deficiency: the impaired ability to discriminate red from green, yellow and orange. People with this type generally perceive yellow and orange as a shade of green.
For this reason, Evans notes, orange isn’t the best choice for a navigation marker in the backcountry.
“Most of the time hiking is okay, but on occasions it is frustrating and sometimes embarrassing,” he says. “Orange isn’t a great colour for me to pick out from the trees, and the triangles are essentially leaf-shaped. If I was hiking on my own, I don’t think I would always go in the right direction. It is dangerous.”
He’s not alone in being colour challenged in the tramping fraternity. Loretha du Plessis is one of the rare women with colour deficiency and sees reds and greens as variations of grey. “When tramping, I really struggle to see the orange markers. They just don’t pop out to me like they do for other people.”
Like Evans, du Plessis is unlikely to see the marker until she is right on top of it and has frequently left the trail or ended up on animal tracks. “It actually adds quite a lot of stress to tramping.”
But these orange triangles are a cornerstone of backcountry trails in New Zealand, where 15,000km of marked track is managed by the Department of Conservation (DOC). Brian Dobbie, senior service designer in DOC’s policy and visitors team, says standardised track marking on public conservation land was introduced in 1994; the materials, shape and use of markers was based on an Australian standard.
At the time, DOC did its due diligence and sought scientific advice on the best colour to use for the greatest proportion of the population. This included two reports by Auckland optometrist Dr Knox Laird. The first highlighted the complex set of challenges posed by forest track markers. Laird noted, ‘there is not a magic colour which will solve the dilemma’: a number of factors, including size, shape and colour, needed to be considered to enhance marker visibility. In a section specific to colour-deficient people, his report noted, ‘The orange markers are not very visible to most colour defectives.’ The report concluded that ‘about 10 per cent of the population would be unable to see the [orange] markers easily’ in the bush.
A follow-up report, which studied the visibility of white markers and those of different orange hues for both colour-deficient and non-colour-deficient people, recommended a slight colour change towards yellow and the choice of a different shape to enhance marker visibility for colour-deficient people.
According to Standards New Zealand’s ‘Handbook on Tracks and Outdoor Visitor Structures’ (2004), the current triangular markers used by DOC are closer to yellow and slightly larger than those reviewed by Laird.
“The [Laird] report did not say that orange was not a suitable colour for markers, but that orange was the ‘least worst’ colour to use,” Dobbie says. “The report also pointed out that no one colour would be suitable for all situations but that orange was the most suitable for the greatest number of people.”
So, what is the best colour for colour-deficient people? According to both Evans and du Plessis, blue markers, already used on some tracks above the bush line, would be their preferred choice. According to the Laird report, however, blue is not suitable in forest conditions, and the perception of the colour blue can be affected in older people. Furthermore, DOC already uses blue markers for management purposes, such as indicating trap lines. Evans and du Plessis also suggest the use of two contrasting colours or a reflective strip. Evans notes that the striped markers used in Europe, where he has tramped, worked well for him.
According to Dobbie, given the extent of tracks managed by DOC, the cost to change the markers would be “prohibitive” and would take many years, and could lead to a confusing two-system marker regime. He also believes that people tramping in Aotearoa must take some personal responsibility for their own safety, and should be able to follow a ground trail and have contingencies for navigational challenges.
Tramper Matthew Lillis, who does a lot of solo tramping, has developed exactly this ability over the years. While not severely colour deficient, he says his capacity to see orange track markers is still reduced compared to non-colour-blind trampers.
“It’s a slight nuisance but not a huge problem,” he says. “[Being colour deficient] just makes it harder to see orange markers, so I have a greater reliance on reading the track and I rely on other signs to keep on the track. I’m a very experienced hiker and navigator now, so I can usually get around it.”
The same is true for du Plessis, who does hike solo but never leads when tramping with others for fear of guiding them off track.
“As I’ve become more experienced, I don’t really pay much attention to trying to find the markers because I know I most likely won’t see them anyway,” she says. “I tend to look for other signs like footprints, broken branches, or plants and roots that have been stepped on. But relying on this alone can still lead me down animal tracks.”
She says she has become better at reading the land and navigating with a map and compass, and always carries a GPS map on her phone.
Evans also isn’t put off solo tramping, saying he would make sure he carried an up-to-date map and was prepared. However, colour-deficient people with limited backcountry skills will be reliant on someone else to navigate. “There is a risk of getting lost or trespassing on someone’s private property,” he says. “Being colour-blind in the New Zealand backcountry gives a taste of what it’s like to be properly disabled where things aren’t set up for you.”