Even though highway
work zone fatalities have been on a big decline for the past 10 years, the
highway work zone remains a dangerous place, for workers and for motorists.
Despite what highway
users may think, work zones are much more lethal to motorists than to
construction workers. Following a peak of 165 workers killed in work zone
accidents in 2005, construction worker deaths declined to 106 in 2010. But in
2010 nearly five times as many motorists were killed in work zone accidents
than were workers (586 total deaths, including workers and motorists).
While work zone
flaggers face drivers in the front lines, behind them in the work zone,
construction workers are at greater risk of injury or death from workplace
accidents, rather than from errant motorists.
Even so, each year
more than 20,000 workers are injured in road construction work zones, according
to data provided by the Federal Highway Administration’s Work Zone Safety and
Mobility Program. Between 2003-2008, these injuries were caused by:
- Contact with objects or equipment
(35 percent)
- Slips, trips, or falls (20
percent)
- Overexertion (15 percent)
- Transportation incidents (12
percent)
- Exposure to harmful substances or
environments (5 percent)
Fatalities at road
construction sites typically account for 1.5 to 3 percent of all workplace
fatalities annually, FHWA reports.
It’s estimated that
road users encounter an active work zone on average one out of every 100 miles
driven on the national highway system, according to a 2014 Transportation
Research Board paper*, “Approximately one injury work zone crash occurred at
every 14 minutes in 2010,” the report says.
Do work zones
actually contribute to an increase in accidents? Intuitively the answer is yes,
but a literature search did not affirm proof. To answer this, the TRB
researchers developed an integrated data set based on 60 long-term work zones,
and analyzed the characteristics of work zone crashes. Their preliminary
analysis results show that the crash rate increased by 24.4 percent under work
zone conditions compared to non-work zones.
*
Estimating the Impact of Work Zones on Highway Safety, by Ozgur Ozturk,
graduate assistant, Rutgers Intelligent Transportation Systems (RITS)
Laboratory, and Kaan Ozbay, Ph.D., and Hong Yang, Ph.D., NYU Polytechnic School
of Engineering.
Danger
in every direction
Danger lurks in every
direction within the work zone, and to survive, contractors and road agencies
must identify the variables.
Highway workers are
at risk of injury from passing traffic, from construction equipment operating
inside the work zone, and in supporting ancillary areas that support
construction, like portable plants. Construction vehicles operating inside the
work zones, as well as entering and leaving, also pose dangers.
These hazards are
known to workers. According to a just-released, February 2015 Australian report*,
workers’ top hazards included:
- Speeding vehicles (the most common
work zone hazard)
- Driver aggression towards road
workers
- Working in wet weather, at night
and close to traffic.
According to the
report, effective measures in improving work zone safety included active police
enforcement and improved driver education. Also, worker perceptions of threats
varied according to their exposure to hazards.
*
Common Hazards and their Mitigating Measures in Work Zones: A Qualitative Study
of Worker Perceptions by Ashim Kumar Debnath, Ross Blackman and Narelle
Haworth, Centre for Accident Research and Road Safety, Queensland University of
Technology.
Innovation
to the rescue?
Now innovative
devices that make work zones safer continue to be improved or introduced, and
many are focused on flaggers.
For example, ROSA,
the Remote Operated Safety Attendant, is a flagger’s tool used to control
traffic from the “safe zone,” away from imminent danger, verbal abuse and
adverse weather conditions. It was developed by Roundspring Technologies and
received the first place American Traffic Safety Services Association
Innovation Award for 2013.
Products like ROSA
are known as automated flagger assistance devices (AFADs), and are designed to be
operated remotely by a flagger positioned outside of the travel lanes.
“There are two types
of AFADs,” says Melisa D. Finley, Texas Transportation Institute in a 2013
paper.* “One type uses a remote-controlled stop and slow sign to alternate the
right-of-way; the other uses remote-controlled red and yellow lenses to
alternate the right-of-way,” she says. “A gate arm [such as used for railroad
crossings] is required only with the latter.”
Although AFADs may
have increased the safety of flaggers, there were concerns that motorists may
misunderstand them and proceed before safe to do so. Finley’s research found
that the violation rate for the stop-slow AFAD without a gate arm is the
highest, and is significantly higher than the violation rate for the red-yellow
lens AFAD (which requires a gate arm). Some motorists still violate AFADs,
especially when there is a visible line of vehicles going in the same direction
as the stopped motorist.
Some contractors make
their own devices. Cold-milling of asphalt requires a moving work zone, and for
night work one contractor has configured small carts with four pneumatic tires
and sign mast (“slow” sign mounted), illuminated by balloon lights powered by a
generator on the carts. Flaggers pull their portable flagger stations along as
the work zones migrate forward.
“It solves the
problem of mobility,” said Dan Darden, vice president of construction,
Gallagher Asphalt, Thornton, Illinois. “If it were a permanent station, you’d
have to have a vehicle sitting there hooked up to a trailer or truck hitch, so
it could be pulled down the road in the moving zone. With this cart, the
flagger can pull it just like a wagon, and put her lunch pail and rain gear in
there.”
The illumination is
required by DOT requirements. “Under Illinois DOT specifications, flaggers have
to be lighted at night,” Darden told Equipment World. Gallagher has been
using its shop-fabricated portable stations for about six years, he said. “The
flaggers like it,” he added. “The stations are very easy to pull, and keep the
flagger from having to climb in and out of a truck, pulling up or backing up.”
* Field
Evaluation of Automated Flagger Assistance Devices in Work Zones on Two-Lane
Roads by Melisa D. Finley, P.E., Texas Transportation Institute at Texas
A&M University.
‘Clear
zone’ positive protection
For more substantial
work over longer periods, highway workers have benefited greatly from working
in “clear zones” created by positive protection from drivers. Typically this
takes the form of a line of concrete “jersey” barriers – anchored or not –
which isolate workers from traffic. In an attempt to forestall “gawker”
accidents on brutal southern California freeways, actual work zone walls have
been constructed of concrete barriers and plywood risers that completely screen
workers from motorists, and vice versa,
FHWA’s rules specify
each state highway agency’s work zone safety and mobility plan include a
description for positive protection in work zones, and implementation guidelines
for federal funded highway projects.
A 2012 TRB survey*
found eight state highway agencies were in the process of updating their safety
and mobility plan, specifically addressing positive protection in work zones,
while 15 agencies had posted revised safety and mobility plans on public areas
of their websites.
According to the
survey, many state highway agencies have dedicated manuals to address work zone
positive protection, including Colorado, Hawaii and North Carolina. In
addition, Arkansas, New Hampshire, and Virginia have extensive positive
protection guidance, and some state agencies have even recommended the use of
proprietary devices in certain conditions.
The authors
recommended these devices:
- Portable concrete barriers, or “Jersey” barriers, for use on
all roadways. Typically they are placed with truck cranes or even
backhoes. Deflection of barrier on impact is up to 3 feet, but pinning
barriers to pavement lessens deflection.
- Ballast-filled portable barriers. These are large polyethylene
containers typically filled with either sand or water, interlocked to form
a longitudinal barrier or channelizer barrier that can either redirect or
provide guidance for vehicles through temporary work zones. They’re
recommended for use on low-speed (45 mph or lower) roadways only. Their
high deflection requires a large longitudinal buffer area behind the
barrier. New-design ballast-filled barriers are available for high-speed
roads.
- Steel barriers. These separate the work area
from open traffic and are recommended for use on all roadways. If
anchored, deflection of barrier is usually less than 3 feet upon vehicle
impact.
- Moveable barriers. These also separate the work
area from open traffic, and are can be used on all paved roadways. They’re
ideal for dynamic or moving work areas that require shielding for varying
widths. Initial cost and on-going operation costs are higher than other
barrier types.
- Truck mounted attenuators. These common products provide a
portable cushion to shield mobile or short-term work areas, and are
recommended for mobile operations and smaller work areas where a truck can
be used as a shield. Roll-forward distance is necessary to allow system to
perform as intended.
- Vehicle arresting systems. These cable/net systems capture
an errant vehicle prior to entering the work area. They’re deployed at the
entrance of work areas where a flare cannot be created using a
longitudinal barrier system. Arresting systems require attachment to a
longitudinal barrier, and a backup arresting net in case one vehicle is
captured.
* Work
Zone Positive Protection Policy Guidance: Synthesis of Devices and State of
Practice by Steven Schrock, Eric Fitzsimmons, Tomás Lindheimer, University of
Kansas-Lawrence; Ming-Heng Wang, Kainan University, Taiwan, and Yong Bai, North
Dakota State University, 2014 Transportation Research Board.
Leveraging
ITS technology
ITS – for intelligent
transportation systems – use a broad range of communications-based information
and electronics technologies, such as sensors and other components in the field
to collect traffic information like volume, speed and video of traffic.
Wireless and wired communications transmit the data, which software processes
and analyzes, after which it’s transferred to end users such as DOTs and
motorists.
Work zone ITS devices
– such as portable changeable message signs – may relay real-time traffic
conditions, such as travel delays through a work zone, or recommend diversion
routes. They may also be used to provide immediate warnings, such as stopped
traffic ahead.
Arizona and South
Carolina are using these message signs to alternate a speed message with a
monetary fine message. According to a recent report,* by using this approach on
Arizona 89 in Prescott, the Arizona DOT reduced by half the number of speeders
driving 15 mph or more over the limit.
Source:
www.equipmentworld.com
