Tiêu chuẩn quốc tế

• Số hiệu / Standard Number: AASHTO WL:2009
• Năm ban hành / Publication date: 2009
• Tình trạng / Status: A - Còn hiệu lực
• Tên tiếng Anh / Title in English: Guidelines for the Selection and Application of Warning Lights on Roadway Operations Equipment
• Số trang / Page: 19

Phạm vi áp dụng / Scope of standard

Introduction

Roadway operations equipment used for construction, maintenance,
utility work, and other similar activities generally operates
within the roadway right-of-way. These vehicles and mobile
equipment operate on all types of roadways, during daytime and
nighttime hours, and under all weather conditions. To improve
motorist and work-crew safety, equipment must be readily seen and
recognized and, therefore, warning lights are provided on the
equipment to alert motorists of potentially hazardous situations.
Amber warning lights have traditionally been used, although lights
of other colors are often added with the intent of helping the
traveling public better see the equipment. Combinations of amber,
blue, and white lights and other forms of warning lights (e.g.,
lighted bars, lighted "arrow sticks," strobes, light emitting
diodes [LED], and alternating flashes) are used. There is a concern
that this variety of lighting on roadway operations equipment has
evolved without adequate consideration of the effects on the
awareness and responsiveness of motorists.

These guidelines have been developed based on the results of a
series of experiments that considered more than 40 lighting
configurations in both static and dynamic environments. The
presence of maintenance personnel, the identification of the
maintenance vehicle, attention-getting, glare, peripheral
detection, and urgency were all metrics in the experiments.
Differing experimental conditions such as weather, the presence of
other vehicles, and time of day were also considered in the
experiments.

One of the primary considerations in the use of these guidelines
is the purpose of the maintenance vehicle. For the purposes of
these guidelines, the term "maintenance vehicle" refers to any type
of vehicle used on the roadway, whether it is being used for new
construction, inspection, or general maintenance. The design of the
warning-light systems may differ based on the vehicle's intended
usage. For example, a snow plow will have different criteria than a
small truck. The following are typical questions to be
considered:

• Will the vehicle be used primarily while moving or
stopped?

• Will the vehicle be used primarily in the daytime or
nighttime?

• Will the vehicle be used primarily in bad weather or good
weather?

• Will there be maintenance workers present around the
vehicle as pedestrians?

Many vehicles are multi-purpose (i.e., they are used for many
different tasks on the roadway). For example, a vehicle may be used
for clearing snow in the winter and in construction and maintenance
activities during the summer. The lighting system on these vehicles
needs to be designed and laid out to include the considerations for
all of the planned or expected vehicle uses.