You can see the results of the
work of Elbert Dysart Botts on most modern
highways throughout the world. They are the raised reflective pavement markers,
or Botts’ dots, that are used as highway markers
for warning drivers.
Dr. Elbert Dysart Botts worked with the California Department of
Transportation or Caltrans where he oversaw research concerned with road
markings and paint stripes. Caltrans began research on raised pavement markers
as far back as 1936, but the research assumed real significance only after the
war years. 1953, spurred by the increasing number of accidents that accompanied
the economic boom, marked a watershed in the use of raised pavement markers.
Prior to this, markings on road pavement were done with painted lines which
tended to be obscured by dirt and to become almost invisible in rain.
The first of Botts’ dots were made of glass and attached to the road
with nails. Once the dots got loose under traffic, the nails became a danger as
they punctured tires. Further development led to the dots being made of ceramic
materials and polyester. The problem of fixing them to pavement led to further
research, which then came up with strong epoxy adhesives which replaced the
nails and eliminated possible traffic hazards from them. While this epoxy is
also credited to Caltrans, it is not known whether Dr. Botts was closely associated with this discovery,
though with his being the head of research, credit would accrue to him as well.
Dr. Elbert Botts was
a chemical engineer who used to teach at San Jose State College before he was
inducted by Caltrans to head their research division Translab.
His initial research concentrated on developing paints that would outlast
concrete and also remain visible in poor light conditions. He had a background
of having worked for a paint company for three years before moving to teaching.
He even included glass beads in the paint to improve visibility through
headlight reflections, but was unable to meet the standards required. This is
when he switched to reflective pavement markers that stuck up above the road
surface.
Most of the field work using
various types of raised pavement markers was conducted on a new freeway in West
Sacramento. The main idea of using raised pavement markers came from the fact
that paint lines disappeared under water when it was raining, and the raised
markers did allow for better visibility. Unfortunately Dr Botts died in 1962, two years after retirement at the
age of 69, and his work was actually filed away, with even Translab failing to acknowledge it in connection
with Dr. Botts.
It was only in 1964 that the new head of Caltrans revived the research and
developed the present day trend of using square reflectors between groups of
the polyester dots.
The system got tacit
recognition when the state legislature made the use of Botts' Dots mandatory in 1966. Botts' Dots are now being used in various colors and in conjunction with painted and other
reflective markers which make roads safer. Yellow dots indicate a split in the
road, whereas red markers indicate lines that cannot be crossed. They are also
used across the road as rumble strips warning motorists to slow down. Blue dots
are used to indicate areas around fire hydrants.
Botts' Dots come in two different basic types.
These are either reflective or plain. The plain ones are white or amber colored and are made of ceramic or plastic material in
a dome shape. The reflective ones are made of polyester that can take high
impact and are square in shape. White dots indicate parallel lanes while center markers are amber. Red dots are an indication
that the driver is in the wrong lane and needs to get off immediately.
There is a difficulty in using
these dots in areas with heavy snowfall as they can be dislodged by snow
clearing equipment. These markers are then put on divots in the road. One
aspect of the dots that has led to its acceptance was the discovery that they
made a thumping noise when tires passed over them, and that, along with the
bumping motion that they created, served notice to drivers that is especially
helpful when driving conditions are poor on rainy days.