Posts Tagged ‘inm’

TRB Releases HMMH-Authored ACRP Document 19: Integrated Noise Model Accuracy for General Aviation Aircraft

Wednesday, October 29th, 2014

by Nicholas P. Miller

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The Transportation Research Board (TRB) recently released ACRP Document 19: Integrated Noise Model Accuracy for General Aviation Aircraft, the result of research conducted by a team of consultants led by HMMH. HMMH was retained to conduct this research project to determine the cause and recommend changes to the Integrated Noise Model (INM), which currently incorrectly computes the noise created by many of the General Aviation Jets. The study compared INM produced sound exposure levels and climb profiles with measured sound exposure levels and radar reported climb profiles. HMMH found that the INM assumed all aircraft used maximum power for takeoff, while in practice, pilots used a “derated” thrust to preserve engine life, creating lower takeoff altitudes, and generally lower levels than the INM computed. HMMH developed a method that would use the INM modeling in a realistic manner, duplicating the procedures used by pilots and are in communication with FAA to assist if possible in correcting the INM modeling. In the future, modeling would be more accurate, noise exposures realistic, and better decisions will be made about land use and aircraft noise around airports where General Aviation jets operate.

TRB Releases HMMH-Authored NCHRP Report 791 – Supplemental Guidance on the Application of FHWA’s Traffic Noise Model (TNM)

Tuesday, October 21st, 2014

by Christopher Menge

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Harris Miller Miller & Hanson Inc. (HMMH) is pleased to announce the release of TRB’s NCHRP Report 791 – Supplemental Guidance on the Application of FHWA’s Traffic Noise Model (TNM), the final product of NCHRP Project 25-34, led by HMMH and supported by a team of consultants.

Noise is an important environmental concern for highway planners and designers, and through 2010, state highway agencies have spent $5.4 billion to abate the noise generated by federally-aided highway projects. Transportation agencies assess different aspects of highway noise to determine or predict community impacts during transportation planning, although procedures have varied by program and agency. The Federal Highway Administration (FHWA)’s Transportation Noise Model (TNM) is a computer program used for predicting noise levels and their impacts in the vicinity of highways. The TNM was developed in the 1990’s by a team led by HMMH under contract to the FHWA. The FHWA has provided substantial guidance for the routine application of the TNM; however, scenarios still exist for which there remains limited or no technical guidance.

Under NCHRP Project 25-34, HMMH was asked to investigate sixteen different research topic areas to identify best practices and provide significant guidance on applying TNM to accurately, consistently, and efficiently model traffic-generated noise in a variety of settings that has not been previously addressed by TNM. The objective of NCHRP 25-34 was to supplement existing guidance on applying the TNM by identifying best practices to model structure reflected noise; bridge expansion joints; signalized interchanges; intersections; area sources (e.g., weigh stations, park and ride lots, toll facilities, and service plazas); median barriers; roundabouts; and tunnel openings. The research determines the sensitivity and accuracy of methods to model multi-lane highways, rows of buildings, topography, ground zones, and tree zones, and identifies best practices for input parameters. The research also synthesizes the state of practice for analyzing the effects of wind and temperature gradients on sound propagation.

The results of NCHRP Project 25-34 are intended for use by experienced analysts, modelers, and designers. Report 791 will be of immediate use to experienced users of TNM by helping them to improve the accuracy and precision of their modeling results and inform decision-making related to the design of noise abatement measures.

FAA Announces the Release of AEDT 2b

Thursday, September 11th, 2014

by Robert C. Mentzer Jr.

The FAA announced on September 8, 2014 that the Aviation Environmental Design Tool version 2b (AEDT 2b)a next generation noise and emission model designed for airports, will be released on May 29th, 2015.  The upcoming version is expected to replace the FAA’s INM and EDMS models which have been used separately for noise and emissions modeling for several decades.  AEDT 2b will combine these two models along with the latest airport and aircraft data to provide airports and consultants a tool to develop noise, emission, and fuel burn results.  One set of data inputs (airfield, aircraft operations, etc.) will allow the user to develop results for all three categories and for different phases of flight.  This will also result in the user being able to understand the consequences of various changes at an airport from one tool.  AEDT 2areleased in 2013 to replace NIRS, is currently available for regional and larger scale analysis such as air traffic redesign studies.

Throwback Thursday (TBT): My First Noise Contours

Thursday, March 20th, 2014

by Mary Ellen Eagan

At the risk of mixing social media platforms (and incurring an eye roll from my teenage daughter), I’d like to announce a new blog series at HMMH:  Throwback Thursdays.

This idea was sparked as a result of the recent renovation of our Burlington headquarters, and the desire to preserve this collage that was prepared for the occasion of HMMH’s 10th Anniversary in 1991: 

HMMH-the early years1981-91

HMMH-the early years 1981-91

Our team has invested significant time scanning each of the photos in the collage, and my hope is that we can find something interesting to say about most of them (well, there are some NSFW things that won’t be shared).

My First Noise Contours

I thought I’d start off with a photo of my first noise contours.  As the date indicates, it was November 1984 (yes, I am that old); I was fresh from Cornell and a summer Internship with the Massport Planning Department; still wearing Birkenstocks and going to Grateful Dead shows (yes, I am that old).  Back in the day, this is what noise contour development looked like:

  • Operational Inputs were developed by typing ATC flight progress strips (see below) into a Lotus 1-2-3 spreadsheet on the company’s only computer – a Xerox (which looked something like this): 

 fl-strips-computer

 

  • Flight tracks were developed in one of two ways:  (a) interviewing the Control Tower manager, who would describe nominal controller instructions to pilots (e.g., Climb to 1000’, then turn on course”), or (2) someone (guess who?) would sit in front of a radar scope marking radar return dots on a piece of acetate – literally, dot-to-dot flight tracks.  These days, I just smile at folks who get worked up for only getting a 99% radar track sample to analyze.
FAA Radar scope, circa 1980s

FAA Radar scope, circa 1980s

 

  • Then the real fun began!  We typed the INM “input deck” (I’m a version 2.7 girl – we old-timers mark our age by first model used) into the computer (my colleagues will tell you about their experiences with punch cards, and submitted it to Control Data Corporation (CDC) over a dial-up modem for processing.  Each run cost several hundred dollars – we did a lot of QC before submitting!   Assuming all went well, we then got to DRIVE to Waltham (20 minutes without traffic) to talk to Manny and get the output – a green and white computer printout and (hopefully) a large plot with contours!
MEE’s First Contours:  Groton-New London, November 1984

MEE’s First Contours: Groton-New London, November 1984

Next up:  Zipatone and Field trips of the 1980s!

 

A “perfect storm” – Recent actions by all three branches of the federal government address more types of aircraft noise, and acknowledge that adverse effects extend beyond traditional noise contours.

Thursday, July 18th, 2013

by Ted Baldwin

Serious federal attention to aircraft noise began around 1960, largely in response to community concerns (okay, complaints) related to the introduction of early air carrier jets (“airliners”), in particular the Boeing 707 and Douglas DC-8.

For the past half century, the federal government has largely focused its attention on aircraft noise associated with succeeding generations of airline jets at commercial service airports.  General aviation (g.a.) airports, g.a. jets, propeller aircraft, and helicopters have been a secondary focus of attention to all branches of the federal government, as illustrated by the following examples:

  • Legislative branch:  Congress has focused on laws phasing out older noisier aircraft over 75,000 pounds, which largely represent air carrier jets.
  • Executive branch:  The FAA’s development of the Integrated Noise Model (INM) has largely focused on modeling air carrier jets, as exemplified by the database’s most extensive coverage for that category of aircraft, with increasing dependence on substitute modeling surrogates as aircraft weight decreases.
  • Judicial branch:  Legal decisions have largely accepted arguments that significant noise exposure and associated liability extend only to the 65 decibel (dB) Day-Night Average Sound Level (DNL) contour, on which g.a. aircraft and helicopters have relatively little effect;  typically the 65 DNL contour from these aircraft alone encompass little – if any – off-airport land.

To build on the “ocean” metaphor in the title of this posting, the airline jet noise “tide” is ebbing, largely as the result of federal legislation and FAA regulations that force the retirement of 14 C.F. R. Part 36 Stage 1 and 2 jets over 75,000 pounds, and require applications for new “type certification” to meet Stage 4 requirements.  Local noise abatement and land use compatibility programs have complemented these federal actions (and frequently benefited from federal funding and implementation support).

One potential federal response might be to declare “mission accomplished” on the noise front, and turn the focus to areas where the tide is rising – both literally and figuratively; e.g., emissions-related contributions to climate change, which appear to be associated with storms that threaten coastal airports and result in operational delays at airports at all elevations.

However, recent actions show that the federal government is taking a different approach, and turning its focus to previously neglected – or at least lower-profile – noise issues associated with g.a. airports, g.a., jets, and even helicopters.  Again, this “changing tide” is reflected across the board at the federal level:

  • Legislative branch:  In the “FAA Modernization and Reform Act of 2012,” Congress prohibited, after December 31, 2015, regular operation in the contiguous 48 states of civil aircraft weighing 75,000 pounds or less that do not meet Stage 3 noise levels.  See http://www.gpo.gov/fdsys/pkg/FR-2013-07-02/pdf/2013-15843.pdf.)
  • Executive branch:  As summarized in its “Aviation Noise Impacts Research Roadmap,” the FAA is supporting a number of initiatives recognizing a broader range of noise issues, such as the accuracy of the INM for modeling g.a. aircraft and enhanced modeling of taxiway noise.
  • Executive Branch:  In a more applied case, the FAA adopted a final rule on July 6, 2012 that requires helicopter pilots to use the North Shore Helicopter Route when operating along the north shore of Long Island, New York.  The purpose of the rule is to “protect and enhance public welfare by maximizing utilization of the existing route flown by helicopter traffic one mile off the north shore of Long Island and thereby reducing helicopter overflights and attendant noise disturbance over nearby communities.”  (see http://www.faa.gov/regulations_policies/rulemaking/media/NYNShoreHelicopterFinalRule.pdf)
  • Judicial branch:  In a recent opinion that denied a petition by the Helicopter Association International (HAI) for judicial review of the preceding mandatory helicopter route, the U.S. Court of Appeals for the District of Columbia Circuit supported the other executive branches in their focus on lower levels of noise exposure related to operations by non-airline aircraft.  (see http://www.cadc.uscourts.gov/internet/opinions.nsf/1C20D137DFF53DAD85257BA600539826/$file/12-1335-1446255.pdf)

It should be noted that the Long Island helicopter route rule addressed in the preceding two bullets was initiated by two federal legislators representing Long Island residents – Senator Charles Schumer and Representative Tim Bishop – who conducted a meeting in October 2007 with the FAA, local helicopter operators, and airport proprietors to specifically address noise complaints stemming from helicopter operations along the north shore of Long Island.  While only the executive and judicial branches took formal action, the process involved significant input by these legislators as well.

The mandatory helicopter route is particularly significant because it represents divergence from several prior federal positions related to the longstanding “line in the sand” that the federal government has drawn at the 65 decibel (dB) Day-Night Average Sound Level (DNL) contour: 

  • First, it reflects major divergence from the prior federal position that reduction of sensitive land uses exposed to noise above 65 dB DNL was a de facto prerequisite for approval and support of noise abatement or compatible land use actions.  In its brief responding to the HAI petition, the FAA acknowledged that the route would not produce any benefit at or above this level of exposure, and noted that it “has authority to act without first demonstrating that a specific noise level has been exceeded.”  Furthermore, the FAA brief cited the “Long Island North Shore Helicopter Route Environmental Study,” which it had tasked the John A. Volpe National Transportation Systems Center to conduct.  That study concluded that prior to the adoption of the mandatory route, no residential population along the route was exposed to noise above 45 dB DNL, even on busy holiday weekends (e.g., around Memorial Day and July 4th, 2011).
  • Second, it reflected the first time – of which this author is aware – that the FAA relied on complaints as a fully sufficient basis for adoption of a formal noise abatement procedure.  In perhaps its most blunt statement regarding complaints, the FAA brief responding to the HAI petition stated “[w]hen people take the time to complain about helicopter noise to the FAA and their elected officials, there is a noise problem.”

The FAA’s justification for and defense of adopting a mandatory noise abatement rule based on noise complaints and with open acknowledgement that the benefit outside the 65 dB DNL contour by a 20dB margin is an extraordinary divergence from decades of FAA policy and decisions regarding noise compatibility actions.  As just one example, readers may recall that in its determination that the Naples (FL) Airport Authority (NAA) adoption of a ban on Stage 2 operations “was unreasonable and unjustly discriminatory” and therefore in violation of federal law, in part because the “NAA’s use of complaints … does not support a finding that the Stage 2 ban is reasonable.”  (”Director’s Determination,” FAA Docket No. 16-01-15, March 10, 2003.)

These recent actions by all three branches of the federal government clearly acknowledge that aircraft noise impacts worthy of addressing in the most formal manner need not be justified by federal land use compatibility guidelines, are not limited to particularly noisy aircraft, and do not even require quantification in decibel-based terms.

While the applicability of these actions as precedents in addressing other noise concerns across the U.S. will undoubtedly be the topic of vigorous debate for some time, airport noise stakeholders – including aircraft operators, pilots, airport proprietors, state and local government land use jurisdictions, airport neighbors, and others – should follow the federal lead in taking a fresh look at creative bases for demonstrating benefits and considering – or reconsidering – the full spectrum of noise abatement and compatible land use measures that might be applied to aircraft noise sources of local concern.