What's wrong with this sign?

Test sign (right) versus current irish road sign design. Each sign illustrated has ben treated equally with simulated 'halation' an effect caused by headlights hitting modern retroflective sign material.

These are signs showing the effects of ‘halation’…

Halation is the effect of headlights hitting a highly reflective material used in modern signs. This causes an overglow, which can make the sign difficult to read, this is particularly challenging for older users.


The sign on the left is a typical Irish motorway sign, in this case from the new M8. The sign on the right is a prototype sign design, part of testing conducted in my postgraduate research at the National College of Art and Design.


‘Halation is a particular problem for older drivers and drivers with contrast sensitivity when letters use high brightness retro-reflective materials’. (Carlson 2006)

With an ageing population profile, it would be desirable to optimise our signs design to ensure the needs of older drivers are addressed.

In the US the Clearview Hwy typeface was created to combat the effects of halation, without the necessity of increasing sign size, as had been recommended by researchers…



“The size of characters on all signs must be increased by at least 30%, which means 1 inch of character height to 38 feet of sight distance, versus the MUTCD standard of 1 inch for 50 feet. This would accommodate motorists testing 20/30 on the standard eye chart…” (Greene, et al 1996)

One aspect of the research was to examine the potential effects of halation on our signs and seek potential design solutions1. My interest was in Irish conditions and the problems faced with design for dual language signs, which I will further cover elsewhere.


An early rough design test, type with an increased x-height, open letter forms, testing for halation.
Above: Initial rough sketch type (green image, left) showing an early halation test. The process was one of redrawing, testing and redrawing over several iterations, exaggerating characteristics of the letter forms to achieve clarity. I should note, that decisions were functional rather than aesthetic, the concept being to establish a set of principles for further research and development - rather than jump to a finished type design without more complete testing. Later sketches attempted to achieve an openness to the individual characters, but with a decreased character width, this was to accommodate longer place names common Irish language place names.
A colour-differentiated design showing the simulated effects of halation
Above: A later test of the effects of halation on a dual language [colour differentiated] sign design. © Garrett Reil, 2008-2009.

Initial tests would suggest that an improved system is possible

Real scenario testing required

The test typeface produced would suggest that a typeface of high x-height, with open letter forms, and compact (rather than condensed) in character, could provide a way forward in designing a new sign system for Ireland’s dual language signs.

It is important to state that the design should not be progressed to a more complete state until some initial user testing (if possible in a road-test scenario) can take place. Such testing with scientific rigour applied could direct further development and improvement of the sign type, and may lead to unexpected outcomes.


(Photos: Irish road sign M8, Wikipedia, creative commons license, prototype sign test showing halation using colour coding and a new test typeface (top right) - other illustrations copyright Garrett Reil, 2009)
1. Some excellent work in this area has been done by Charles Meeker and James Montalbano in conjunction with the Texas Transportation Institute, in developing the Clearview Hwy typeface for US signs. That work is covered extensively elsewhere, see the Clearview Hwy website for a list of articles.

Share |

blog comments powered by Disqus