Wisconsin DOT
EXPERIENCE WITH SNOW BUILD-UP ON LED
TRAFFIC SIGNAL LENSES
JOANNA BUSH, P.E.
STATE TRAFFIC SIGNAL SYSTEMS ENGINEER
14000
Size of the
Problem
WisDOT currently
owns/maintains
approximately 950
signalized intersections.
All intersections were
upgraded to LEDs by
2006.
12000
10000
8000
6000
4000
2000
Green Arrow
Yellow Arrow
Red Arrow
Green Ball
Yellow Ball
0
Red Ball
In Wisconsin we
historically have
experienced approx. 2
snow events per year
where conditions are
just right to obscure
signal heads.
Winter
2008/2009
A handful of Fortran’s
Snow Sentrys were
purchased in 2008 and
installed at isolated
intersections around
the state.
Photo is from a light snow event.
McCain – Scoop Tunnel Visor
Winter 2010
WisDOT purchased and
installed a handful of
McCain’s Scoop Tunnel
Visors and has installed
them at the same
intersections as the
Snow Sentry
installations so that we
can do side by side
comparison.
Also purchased
Intelight’s Automatic
Lens Defrosters.
Intelight – Automatic Lens Defroster