**EVALUATION OF A WAYSIDE HORN AT TWO**

**HIGHWAY-RAILROAD GRADE CROSSINGS**

In an effort to alert motorists and pedestrians to the presence of an
approaching train and avoid accidents at highway-railroad grade
crossings, locomotive engineers regularly sound a train-mounted horn as
they approach the intersection. Locomotive engineers begin sounding the
horn approximately 1/4 mile from the highway-railroad grade crossing.
This warning exposes a segment of the local community near the tracks to
the sound of the train horn as well as motorists and pedestrians who may
be approaching the grade crossing. However, residents living near the
grade crossing are not the intended target of this auditory warning and
the train horn noise is perceived by many residents living near grade
crossings as highly annoying.

One alternative proposed to address the adverse effects of train horn
noise is a stationary horn mounted at the grade crossing. The stationary
horn, referred to here as a wayside horn, is sounded in place of the
train horn as the train approaches the grade crossing. Previous research
addressing wayside horns have examined whether the wayside horn is
detectable by motorists. Wayside horns evaluated in the past were less
detectable than commonly used train horns (Keller and Rickley, 1993).
The train horns tested contain a broader band signal that is more
difficult to mask than the wayside horn. Rapoza and Rickley (1995) using
acoustical data determined that a wayside horn with a single tone and a
maximum sound level of 87 dBA would be less detectable inside a moving
motor vehicle than the Nathan 5 chime and Leslie 3 chime train horns
that predominate most locomotives today. Another study (Saurenman and
Robert, 1995) evaluating a different wayside horn, but with a maximum
sound level of 85 dBA, found similar results. The motorist could detect
the audible warning up to 400 feet from the grade crossing when the car
was idling. However for a moving car in which the background noise level
was in the 55-65 dBA range, the motorist would fail to detect the
wayside horn in time to stop before arriving at the grade crossing.

Previous research on wayside horns still leaves many important questions
unanswered. One critical question that needs to be answered is whether
the community noise impact of a wayside horn reduces annoyance to the
local community compared to a train-mounted horn or whether it simply
moves the area of impact to a different part of the community?
Currently, there is no research that specifically addresses whether a
wayside horn would reduce the noise impact on the community. If the
wayside horn is to be successful it must minimize the impact of the
auditory warning on residents living in the vicinity of the grade
crossing. The current study addresses this concern.

Another question that needs to be answered is whether safety is
maintained when a wayside horn serves as the auditory warning in place
of the train horn? Previous research has addressed the question of
effectiveness in maintaining safety by looking at detectability of the
horn. Using detectability of the train horn as a performance measure may
not be directly related to motorist behavior. A different method of
evaluating safety is to examine driver behavior directly. Observing
motorist behavior at the grade crossing will help determine how auditory
warnings influence driving behavior. The current study attempts to
address this concern by examining how motorists respond in the presence
of a wayside horn and a train horn.

It is important to emphasize that the current research evaluates the
viability of the wayside horn as a warning concept. Although the study
evaluated one particular device in terms of its effectiveness in warning
motorists and minimizing community noise impact, the study is intended
as a test of a class of auditory warnings located at the grade crossing.
To the extent other auditory warnings are designed similarly, similar
performance would be expected.

The study was conducted in Gering, Nebraska and compared the performance
of train horns on Union Pacific locomotives (Leslie 3 chime) to a
prototype wayside horn. The type of train horn evaluated was determined
by the type of horn mounted on the locomotive. The majority of the
trains observed moving through Gering (approximately 95%) consisted of
Union Pacific locomotives carrying coal. These Union Pacific locomotives
possessed a Leslie 3 chime horn. The wayside auditory warning device
selected for evaluation was designed by Merrill Anderson of Railroad
Consulting Services, Inc. The device consisted of a horn, a tone module
containing the sound recording of an air horn, a control board that
received the signal from the track circuitry and activated the horn. On
top of the horn case was a strobe light that served as a visual signal
for the locomotive engineer that the wayside horn was sounding. A small
circuit board and detector installed inside the horn case activated the
strobe light if the horn emitted a signal at least 80 dB. If the wayside
horn was less than 80 dB, the strobe light remained off. The activation
of the wayside horn was tied to the same circuitry that activated the
crossing gates, flashing lights, and crossing bells.

For the current evaluation, two wayside horns were mounted on a utility
pole with each horn directed toward oncoming traffic, at each of three
grade crossings in Gering Nebraska. We monitored performance at two of
these grade crossings: Tenth Street and Country Club Road.

**Community Noise Impact**

To evaluate the community noise impact of the wayside horn, two surveys
were administered by telephone. The surveys asked respondents how
annoyed they were by the two auditory warning devices, the activities it
interfered with and what actions they took in response to the noise. The
first survey measured the impact of the train horn on community noise.
The second survey measured the impact of the wayside horn on community
noise. Data from the two surveys were compared to evaluate the
difference between the two warning devices on community noise impact.

The evaluation of community noise impact indicates that the wayside horn
tested is considerably less annoying than the train horn. The wayside
horn reduced noise levels to a point where far fewer residents were
highly annoyed. The wayside horn was less likely to interfere with
activities inside or outside the home and generated fewer actions to
minimize the noise.

The variable that best predicted if someone was highly annoyed was the
frequency with which the horn was heard. The greater the horn count, the
more likely a resident was to be highly annoyed. High annoyance was also
related to the activities that were interfered with. The relationship
between activity interfered with and high annoyance varied by time of
day. During the day, interference with conversation contributed to high
annoyance. During the evening, interference with both conversation and
reading contributed to high annoyance. Finally, during the night, only
interference with sleep contributed to high annoyance.

**Acoustic Analysis**

The objective of the acoustic analysis was to document the sound level
and frequency content of the in-service locomotive horn and the wayside
horn. In addition, the acoustic data collected was compared to the
community noise impact data collected from the survey of the local
residents to examine the relationship between noise level and annoyance.
The objectives were met by conducting sound level measurements of both
the locomotive horn and the wayside horn at fourteen sites surrounding
the three grade crossings in Gering, NE.

At peak sound levels, the wayside horn was approximately 13 dB quieter
than the train horn. The lower sound level of the wayside horn compared
to the train horn was a significant factor in explaining why the wayside
horn was perceived as less annoying than the train horn. Unlike the
train horn, the wayside horn did not meet the minimum sound level
required of train horns. However, this study did not directly answer
what the actual sound level should be for motorists to reliably detect
this signal inside the vehicle. The frequency distribution of the
wayside horn was similar to the train horns measured in this study.

For the 14 sites where sound measurements were collected, the wayside
horn had a negative community impact only during nighttime hours using
guidelines developed by the FTA. Only the sites defined as severe impact
resulted in community annoyance high enough to require action to
mitigate the noise. For the wayside horn, the location of the sights
defined as severe were all within 100 feet of the track. By contrast,
locations defined as severe impact for the train horn were located up to
1000 feet from the track. Clearly, the wayside horn impacted residents
over a smaller geographical area.

The current study was unable to establish a relationship between
measured sound level and perceived annoyance value, as measured in the
two surveys. In part, this is due to measurement error in assigning
sound level values to each respondent. However, previous research has
been unable to attribute more than a small portion of the variance (20%)
in perceived annoyance to physical noise levels. Other factors such as
frequency with which the horns are heard and the activities the
respondent is engaged in at the time the horn sounds also play a role.

**Evaluation of driver behavior**

The use of an alternative warning device to the train horn must also
provide an effective warning to the motorist, if accidents are to be
prevented. The primary objective of the driver behavior evaluation was
to assess the safety of the wayside horn. To meet this objective, we
used video cameras to record and observe driver behavior at two grade
crossings for both the train horn and the wayside horn. We observed when
motorists drove through the grade crossing following activation of the
warning systems. We measured both the frequency of the violations and
the time to collision. Violations were selected rather than accidents
because they occur at a much higher frequency than accidents. Accidents
at one or two grade crossings occur at too low a frequency to detect
performance differences.

This evaluation of motorist behavior suggests that the wayside horn does
not result in behavior that puts the driver at increased risk compared
to the use of the train horn. The frequency of violations was lower for
the wayside horn than the train horn, while the time to collision and
violation time was not statistically or practically different for either
warning system.

In both the train horn and wayside horn conditions, driver behavior was
determined in part by the presence of the gates. To the extent that gate
behavior controls motorist behavior, differences between the two warning
devices may have been masked. Data from Richards et al\'s (1991) study
on optimal warning times indicates that as the time delay increases
between when the warning is initiated and the gates completely descend,
motorists are more likely to continue through the grade crossing without
stopping. The gate descent time in this study was relatively short (10
s). This short descent time may have reduced the overall violation rate
compared to grade crossings with longer descent times. Motorist behavior
with the two warning systems may or may not vary as gate descent time
increases. Evaluating the two warning systems with longer gate descent
times would provide an answer to this question. An evaluation of the two
warning devices without gates at the crossing would indicate how these
devices compare without the influence of gates.

**Implementation Issues**

The current study did not set out to evaluate how the wayside horn
*should be* *implemented* to maximize safety while minimizing community
noise impact. Nevertheless, a variety of implementation issues will
impact safety at the grade crossing as well as community noise. Some of
these issues were identified along with issues they raise and potential
solutions. These issues included method of activation, hardware design
and standardization.

Two methods of activation were identified: track circuitry and engineer
activated. There are trade-offs that must be considered in selecting
either method. The engineer activated method has not been subjected to
evaluation in revenue service, but remains a promising approach.
Activation by track circuitry with constant warning times is a viable
approach if the track circuitry is reliable. Assuming the track
circuitry is reliable, the opportunity to use this method will depend
upon the availability of grade crossings with constant warning track
circuitry. Currently constant warning time track circuits are available
at only a small percentage (13 %) of the grade crossings protected by
active warning systems (Volpe Center and PRC, In Preparation). Although
the auditory warning could also be activated by fixed block track
circuits, this approach is problematic. As the time between activation
of the warning device and the actual presence of the train increases,
motorists are less likely to heed the warning.

The current evaluation also identified several issues related to the
design and maintenance of wayside horn. Exposure to the elements
impaired the performance of several hardware components. The components
of the wayside horn must be designed to withstand the extremes of
weather found in the United States. The system also needs to be designed
to facilitate ease of maintenance. Important design features that
contribute to ease of maintenance include: minimizing the number of
components, using modular components that are easy to replace, and
designing the housing to facilitate ease of access. Finally,
standardization of the auditory signal was recommended to facilitate
quick motorist recognition and action.

**Conclusions**

In this study, the wayside horn reduced community noise without
adversely affecting safety. However, this study was limited in scope. It
evaluated community noise in only one community and measured safety at
only two grade crossings. This type of evaluation needs to be repeated
to determine to whether the results apply over a broader range of
communities and grade crossings, and over a longer period of time.
Evaluating this warning concept under a wider array of conditions (i.e.,
different sound levels, variable gate descent times, without gates,
different activation method) will also help to determine whether the
wayside horn can accommodate an adequate level of safety as well as an
acceptable community noise level.

**References**

Keller, A.S. and Rickley, E. (1993). *The Safety Of Highway-Railroad
Grade Crossings: Study of the Acoustic Characteristics Of Railroad Horn
Systems*. Report No. DOT/FRA/ORD-93/XX. Washington, D.C: U.S. Department
of Transportation, Federal Railroad Administration.

Rapoza, A. and Rickley, E.J. (1995). *The Safety of Highway Railroad
Grade Crossings: The Effectiveness of railroad Horn Systems*. Report No.
DOT/FRA/ORD-95/XX. Washington, D.C: U.S. Department of Transportation,
Federal Railroad Administration.

Richards, S.H., Margiotta, R.A. and Evans. G.A. (1991) *Warning Time
Requirements at Railroad-Highway Grade Crossings with Active Traffic
Control*. Report No. FHWA-SA-91-007. U.S. Department of Transportation,
Federal Highway Administration.

Saurenman, H. and Robert, W.E. (1995). *Test of Wayside Horn Concept for
Audio Warnings at Grade Crossings: Final Report*. Los Angeles, CA: Los
Angeles Metropolitan Transportation Authority.

Volpe National Transportation Systems Center and PRC. (In Preparation).
*Highway-Railroad Grade Crossing Active Signal Systems Analysis*.
Washington, DC. Federal Railroad Administration.