Is train horn noise a problem in your
John W.P. Redden, P.E.
Senior Railroad Engineer
Kansas City, Missouri
The locomotive horn is an effective deterrent to accidents at
grade crossings. However, the sound level from the locomotive horn
creates a significant noise that often depreciates the quality of
life in communities where trains operate. The Federal Railroad
Administration (FRA), on June 24, 2005, issued its Final Train
Horn Rule that allows Public Authorities to establish Quiet Zones
where locomotive horns are not routinely sounded at the public
grade crossings. The result may be improved living conditions as
loud train horns are silenced. However, a warning device (the loud
train horn) that has successfully prevented many grade crossing
accidents has been eliminated. So how can the silencing of train
horns and grade crossing safety coexist?
Let's do a quick comparison of conversation (normal and loud) and
train horn noise levels. Normal conversation occurs within a range
of 60 and 70 dBA. A loud voice is between 70 and 80 dBA and a
shout is between 80 and 90 dBA. Audible communication usually
ceases when background noise exceeds 90 dBA. The noise from a
train horn (over 110 dBA at 100 feet) can have an impact greater
than a siren.
How does train horn noise diminish as distance from the
The FRA has modeled how the train horn sound propagates and
dissipates from its source. The FRA model states that train horn
noise is reduced by 4.5 dBA whenever the distance from the train
is doubled. This horn noise dissipation is caused by divergence of
sound and ground interference. The FRA model also considers
shielding from buildings and includes a 3 dBA reduction at the
first row of buildings, located 200 feet from the track, and
additional 1.5 dBA reductions for each succeeding row at 400, 600,
800 and 1,000 feet. Assuming an average of 104 dBA of horn noise
at 100 feet from the train, the chart at left shows how the FRA
models the dissipation of noise as distance from the grade
crossing increases. This model shows that speech interference can
begin to occur approximately 7,000 feet from the track when the
train horn is sounding. People, outside and closer than 1,500 feet
from the track, may have to shout to be heard. Outside
conversations, closer than 400 feet from the track, usually have
to cease until the train passes by.
What are the train horn sound requirements in the new
FRA Train Horn Rule?
- The locomotive horn must be sounded 15 to 20 seconds prior
to and until the train arrives at the crossing.
- The locomotive horn should not be sounded greater than 1/4
mile in advance of a grade crossing.
- The minimum sound level of the locomotive horn is 96
decibels (dBA) 100 feet in front of the train in its direction
- The new maximum is 110 dBA at 100 feet in front of the train
in its direction of travel.
Does the Train Horn Rule provide a method to
simultaneously silence the locomotive horn and promote grade
The new FRA rule sanctions the establishment of "Quiet Zones"
where the conventional train horn may be silenced at the grade
crossings. Flashing light signals with gates, as the minimum level
of protection, are required at all grade crossings within new
Quiet Zones. The grade crossing warning devices must be activated
by constant warning circuitry. Each highway approach to every
public and private grade crossing within a new Quiet Zone must
have an advance warning sign that advises motorists that train
horns are not sounded at the crossing. In addition, the
installation of one of several FRA-approved Supplemental Safety
Measures or Alternate Safety Measures may be required at all or
some grade crossings within the Quiet Zone.
What is a Quiet Zone?
A "Quiet Zone" is a segment of rail line where locomotive horns
are not routinely sounded while the train approaches the public
highway/railroad grade crossings within the corridor. The minimum
length of the Quiet Zone is 1/2 mile.
How can a Quiet Zone be established?
The FRA Train Horn Rule permits a Quiet Zone to be established via
the following avenues:
- The calculated Quiet Zone Risk Index (QZRI) is determined to
be less than the Nationwide Significant Risk Threshold (NSRT).
In this situation, no further improvements or upgrades are
necessary at the crossings within the proposed Quiet Zone.
- One of several FRA-approved Supplemental Safety Measures are
installed at all of the crossings in the proposed Quiet Zone. It
is the opinion of Hanson-Wilson that this is the most direct and
safest method to establish a Quiet Zone.
- One of several FRA Supplemental Safety Measures or Alternate
Safety Measures is installed at some of the crossings in the
proposed Quiet Zone to reduce the Quiet Zone Risk Index (QZRI)
below the Nationwide Significant Risk Threshold (NSRT).
- One of several FRA Supplemental Safety Measures or Alternate
Safety Measures is installed at some of the crossings in the
proposed Quiet Zone to reduce the Quiet Zone Risk Index (QZRI)
below the Corridor Risk Index with horns.
The FRA has a Quiet Zone Calculator Tool on its website to
assist communities in determining the existing Corridor Risk Index
with horns and the proposed Quiet Zone Risk Index using various
safety enhancement options and crossing upgrade scenarios.
What is the Quiet Zone Risk Index?
The Quiet Zone Risk Index (QZRI) is a measure of risk to the
motoring public in the Quiet Zone and reflects the increased risk
due to silencing of the train horn and the reduced risk due to the
implementation of Supplemental Safety Measures or Alternate Safety
What is the Nationwide Significant Risk Threshold?
The Nationwide Significant Risk Threshold (NSRT) is a measure of
risk that reflects the average nationwide level of risk at public
grade crossings equipped with flashers and gates and where train
horns are sounded.
What is the Corridor Risk Index with horns?
The Corridor Risk Index with horns is a measure of risk to the
motoring public and reflects the risk if the train horn was
sounded at each grade crossing in the Quiet Zone.
Once a Quiet Zone has been created, can its Quiet Zone
status be lost?
It depends. A Quiet Zone can remain in effect, without FRA annual
monitoring, if it was created by installing one of the approved
Supplemental Safety Measures at each and every grade crossing in
the proposed Quiet Zone. However, if the Quiet Zone was
established by reducing the QZRI to below the NSRT, then the Quiet
Zone will be subject to annual review by the FRA. The QZRI will
increase if there are accidents at the crossings within the Quiet
Zone. The NSRT can also fluctuate. If the annual FRA review
determines that the QZRI is above the NSRT then the Public
Authority will have to take additional steps, and may incur
additional costs to lower the QZRI sufficiently to maintain the
Quiet Zone. In addition, the FRA may review the status of any
Quiet Zone at any time.
What are Supplemental Safety Measures?
A Supplemental Safety Measure (SSM) is a safety system that is
provided by the Public Authority and determined by the FRA to be
an effective substitute for the locomotive horn. The FRA
Supplemental Safety Measures that will allow the silencing of the
locomotive horn with the Quiet Zone include the following:
- Paired one-way streets with full closure gates.
- Median barriers in combination with two-quadrant gates.
- Four-quadrant gates.
- Permanent crossing closure.
- Temporary crossing closure (during night hours).
me more about Paired One-Way Streets
The Paired One-Way Streets option involves full closure gates that
completely block all approach lanes to the crossing. The gate arm,
in the horizontal position, must extend across the road to within
one foot of the far edge of pavement if one gate is used. In this
situation, the edge of the road opposite the gate mechanism must
have a barrier curb to prevent motorists from veering onto the
shoulder and driving around the descended gate.
If two gates are used, one on each side of the road as shown on
this schematic, the ends of the gate arms in the down position
must leave a gap of no more than two feet from each other. The FRA
also proposes that the Paired One-Way Street Option include
constant warning time circuitry and signs alerting motorists that
the train horn does not sound.
Tell me more about Median Barriers
Many grade crossing accidents occur when queued motorists pull out
of their lane and attempt to drive around the lowered gates.
A "Channelization Device" or median barriers in combination
with two-quadrant gates are intended to constrain vehicles to wait
in their lane until the train passes through the grade crossing.
The line of median barriers begins at the end of the railroad gate
when in its horizontal position, thus obstructing the gate
runaround scenario. The FRA recommended length of the line of
median barriers is 100 feet, with 60 feet minimum. Therefore,
median barriers will impact traffic maneuverability to and from
business entrances or driveways if they are located in the near
vicinity of the grade crossing. In order for Median Barriers to
work, these entrances must be closed, relocated or converted to
"right-in, right-out." Median barriers are relatively inexpensive
as compared to other safety enhancement options.
The median barrier type pictured above provides vehicular
containment but allows emergency vehicles to drive over them and
then spring back to the vertical position.
Tell me more about Four Quadrant Gates
Four quadrant gates are intended to completely block all road
lanes on both sides of the tracks at the grade crossing and thus
eliminate the gate runaround scenario. They are effective in
preventing accidents by effectively sealing the crossing from
vehicles. However, slow-moving vehicles could conceivably be
trapped in the railroad zone after the gates descend. Vehicle
Presence Detectors (VPD) are often installed that sense the
presence of slow-moving vehicles to keep the "supplemental" exit
gate arms in the vertical position until all vehicles have cleared
the track crossing area. The FRA also requires that four quadrant
gates include constant warning time circuitry and signs alerting
motorists that the train horn does not sound. The cost for a
four-quadrant gate system is relatively expensive compared with
other SSM options. Furthermore, the railroads have issues
regarding the additional maintenance costs, especially maintenance
of the Vehicle Presence Detector system.
Tell me more about Permanent Crossing Closure
The grade crossing is permanently eliminated so that vehicles have
to use other at-grade or grade separated crossings.
Tell me more about Temporary Crossing Closure
The temporary closing of the crossing during the same period every
24 hours will allow the locomotive engineer to silence the train
horn during the period when the crossing is closed. When the
crossing is physically closed by barriers, a relay automatically
activates a "crossing closed" signal that confirms to the
locomotive engineer that the crossing is closed. As long as the
locomotive engineer can see the "crossing closed" confirmation
signal, he will not be required to sound the train horn.
What are Alternate Safety Measures?
Alternate Safety Measures (ASMs) are safety systems or procedures,
other than Supplemental Safety Measures, that are provided by the
Public Authority and after review and analysis by the FRA are
determined to be an effective substitute for the locomotive horn.
Examples of Alternate Safety Measures are:
- Supplemental Safety Measures that do not fully comply with
the FRA requirements;
- Programmed Law Enforcement;
- Public Education and Awareness; and
- Video Enforcement
Programmed Law Enforcement involves the
ongoing measurable monitoring and traffic law enforcement of the
crossings within the Quiet Zone.
Public Education and Awareness is directed at
the vehicle drivers and pedestrians within the community to
emphasize the risks associated with grade crossings.
Video Enforcement involves the installation of
video equipment at the grade crossing that monitors the vehicle
traffic flow and records traffic violations. The surveillance
system is intended to be constant but the camera only activates
and records an event when a violation is detected. Although Video
Enforcement may discourage motorists who may consider driving
around the railroad gates, it cannot physically prevent accidents
at crossings because it does not provide any complimentary
protection to compensate for the elimination of the train horn
warning, which is what Supplemental Safety Measures provide.
Video Enforcement is an "after the fact" safety enhancement
option. Public awareness efforts are therefore critical to the
success of Video Enforcement. The public must be informed that
violations will result in penalties. Although local driver
responsibility may improve due to the awareness of Video
Enforcement, out-of-town vehicle behavior may be at risk. There is
also the concern that a judge may not accept Video Enforcement to
convict errant drivers. Without court enforcement, this
alternative would fail to provide the intended safety enhancement.
It is also noted that video equipment requires continuous
monitoring and ongoing maintenance by the road authority.
How do Automated Train Horns fit into the mix?
The FRA Interim Train Horn Rule allows Automated Train Horns
(Wayside Horns) to be used as a one-for-one substitute for the
train horn at individual or multiple at-grade crossings, including
those within Quiet Zones. The Wayside Horn is a stationary horn
located at a highway-rail grade crossing, designed to provide
audible warning to oncoming motorists of the approach of a train.
The crossing must be equipped with flashing lights and gates. The
FHWA has granted Wayside Horns with interim approval as traffic
Tell me more about Wayside Horns
Wayside Horns are mounted on poles at the crossing and emit a
louder, longer and more consistent audible alarm than the
conventional train horn when the train is 1/4 mile from the
crossing. The Wayside Horn sound is directed right toward
motorists and pedestrians on the roadway. Wayside Horns typically
provide a minimum of 25 to 30 seconds of audible warning. The FRA
requires that Wayside Horns provide a minimum of 92 and maximum of
110 dBA when measured 100 feet from the horn in the direction it
Wayside Horns are designed to sound like a train horn. The
circuit control board, upon receipt of the signal from the
railroad's signal house, cycles through the standard railroad
whistle pattern of two long blasts and one short blast followed by
another long blast. This pattern continues until the train reaches
the crossing and then the Wayside Horns stop sounding. When the
train activates the crossing signal system, the Wayside Horns are
activated. The horn confirmation signal is activated if the
speaker located in the horn detects the alarm sound at the
required decibel level. As long as the locomotive engineer can see
the horn confirmation signal, he will not be required to sound the
train horn unless he detects some type of emergency. If the
locomotive engineer cannot see the horn confirmation signal at the
crossing, he is instructed to sound the train horn.
What is the comparative noise footprint of the
conventional locomotive horn vs. Wayside Horns?
It is estimated the noise from ATHs impact less than 10% of the
area impacted by the noise from a conventional locomotive horn.
The following schematics, developed by Railroad
indicate the comparative noise footprint of the area impacted by
the sound of the conventional locomotive horn versus the ATH.
The noise intensity of Wayside Horns does not ramp up as the
train approaches the crossing and the "Doppler Effect" of the
conventional locomotive horn is missing. The public is therefore
not able to conclude from which direction the train is approaching
upon hearing the train alarm. However, safety experts acknowledge
that often the public does not know from which direction the train
is approaching with the conventional locomotive horn because
either the vehicle windows are up, the car radio is on or people
are not paying that close of attention.
What steps must the community take to achieve a Quiet
Zone that satisfies the requirements of the FRA Rule?
The establishment of a Quiet Zone is not an "overnight" event. It
may be an odyssey requiring careful strategy and perseverance
followed by enormous quality-of-life rewards. A community wishing
to create a Quiet Zone must judiciously evaluate and then select
the optimal safety treatments that provide maximum benefit at
minimum cost without compromising public safety at the grade
crossings in the Quiet Zone. A field "Diagnostic Team Meeting" at
the various crossings in the proposed Quiet Zone involving the
appropriate agencies is also a typical step in the process. Grade
crossing inventory forms must also be updated for submittal
purposes. After the Quiet Zone "game plan" has been crafted, the
FRA requires the community to prepare and distribute first a
Notice of Intent and then a Notice of Quiet Zone Establishment to
appropriate agencies. The requirements for these documents are
found in the FRA Train Horn Rule.
The FRA has provided various safety enhancement options to silence
or mitigate train horn noise. Each of these options will be more
or less appropriate based on the unique situation in each specific
community. Communities wishing to silence the train horn while
maintaining grade crossing safety should understand the FRA Train
Horn Rule and the quality-of-life and safety implications for both
communities and railroads.
Communities should also understand the advantages and
disadvantages of the various Supplemental Safety Measures and
Wayside Horns for the specific crossing in their town. A community
may benefit from having an engineering expert experienced with
railroad crossing safety and the FRA Quiet Zone Rule to analyze
the various grade crossings in their town, perform a cost-benefit
analysis and recommend the optimal arrangement of FRA-approved
safety options that will achieve train horn relief, without
compromising grade crossing safety, based on the town's
objectives, priorities and budget. The engineering expert should
also be able to:
- Represent the community during the Diagnostic Team Meeting
- Navigate the project through the regulatory approval process
including Notice of Intent and Notice of Quiet Zone
Establishment preparation and submittals;
- Prepare design drawings and specifications for construction
- Provide construction support services to ensure that the
safety options are properly installed.
John Redden, P.E., is a Senior Railroad Engineer at
Hanson-Wilson in Kansas City, Missouri. Redden spent 19 years in
the Design and Construction Department of Conrail in Philadelphia,
where he served in the Civil Engineering and Public Improvements
offices. He is a member of the American Railway Engineering and
Maintenance-of-Way Association and participates in Committee 1,
Roadway and Ballast. He can be reached at (816) 701-3118 or