Abstract: Maintenance of highways often involves mobile work zones for
various types of low speed moving operations such as striping and sweeping. The
speed differential between the moving operation and traffic, and the increasing
problem of distracted driving can lead
to potential collisions between approaching vehicles and the truck-mounted
attenuator (TMA) protecting the mobile work zone. One potential solution to
this problem involves the use of a mobile work zone alarm system. This report
describes the field evaluation of two types of mobile work zone alarm devices:
an Alarm Device and a Directional Audio System (DAS). Three modes of operation
were tested: continuous, manual, and actuated. The components of the evaluation
included sound level testing, analysis of merging distances and speeds, and
observations of driving behavior. The sound level results indicated that the
sound levels from both systems fall within national noise standards. All of the
tested configurations increased the merging distance of vehicles except for the
Alarm Actuated setup. The DAS Continuous setup also reduced vehicle merging
speeds and the standard deviation of merging distance. In some instances,
undesirable driving behaviors were observed for some of these configurations,
but it is unclear whether these driving behaviors were due to the presence of
the mobile work zone alarm device. Analysis of alarm activations indicated that
factors such as horizontal curves and movement of the TMA vehicle created false
alarms and false negatives. The research demonstrated that mobile work zone
alarms have the potential to be an effective tool in improving safety by
providing audible warnings. Further refinements to the systems, such as
modifications to the alarm sound and warning message, could improve system
effectiveness.
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Report number: cmr15-011
Published: June 2015
Project number: TR201412
Author(s): Henry Brown, Carlos Sun and Tim Cope
Performing organization: Department of Civil & Environmental Engineering, University of Missouri
