Airport Noise Analysis Using the Integrated Noise Model

As we learned in lecture, airport noise can be a serious and controversial problem. If noise is a problem, airport operators have several options for mitigation (see the matrix). How do we know if noise is a problem? We need a tool to quantify noise exposure levels. The Integrated Noise Model (INM) is such a tool.

Much more detailed data and procedures would be used in a actual study, and the data and analysis presented in this lab are for EDUCATIONAL PURPOSES ONLY! However, the lab will familiarize you with the general procedure and some of the more important data elements that can affect noise levels. These elements include:

With this information, the INM can plot noise contours (iso-noise level lines) around runways, at several key noise levels. Each of the contours represents a constant noise exposure level. Since airport noise fluctuates, and there is generally a greater impact of nighttime noise than other, we need a metric for comparison. One such metric is known as the DNL or Day-Night Level. The DNL is basically a 24 hr. average sound level, in decibels, where the nighttime operations have been weighted by an additional 10 dB.

These plots, in themselves, are not useful unless we can overlay them on maps of existing or future land use since not all land use is compatible with airports (see the table). As a result of airport or neighborhood growth, these incompatibilities do exist. Sometimes, the impacts can be mitigated (note Birmingham's policy on free insulation for homes within specified noise contours).

Applications of such a product (the INM) should be obvious. We could use the output to make policy decisions on future airport operations or development strategies. While the contour map represents only a snapshot of hypothetical existing conditions, one can readily see the benefits of developing alternative maps for current (base year) or future year scenarios.

Objectives

The objective of this lab is to determine the noise impact of an airport, in this lab a rough approximation of the Des Moines International Airport. For the purpose of this lab we will assume that presently the airport only allows flights to depart on two paths. The airport is planning to allow aircraft to depart on six departure paths. The airport has asked you to compare this scenario to current use and to quantify the additional impacts, if any, and make recommendations on ways to limit the noise effects.

The goal of this lab is not to overwhelm you with learning new software such as the INM. Much of the input into the INM software is intuitive, but not user friendly. If you try to do this lab without carefully reading instructions and attempting to understand what the software is doing, you will have problems. We have tried to indicate the purpose of each step to help you better understand the software.

Procedure

Collecting all of the required data represents a significant task. Much of the data have been assembled for you, and we will use the INM and MapInfo to do a cursory analysis.

Step 1: Collect/Prepare Data for The INM

Download the data files for the lab in a self-extracting zip file: Click on the link, Save to disk (C:\User), Start explorer then explode the files by double clicking "air.exe". The files contained are:

Create a directory C:\User\Mapinfo and place all of the Mapinfo files in it. (all files except the .xls and .dbf file)

Step 2: Calculate typical flight operations

The analysis for this lab compares two "cases" of flight arrival and departure flight paths. Departure paths are "tracks" that a plane follows on its take-off path. See handout. For the INM, we will need to determine the percent of flights departing or arriving to/from destination/origin cities for use in the INM model. We will use flight information derived from the Official Airline Guide (OAG).

  1. In the files you downloaded, find ops_arpt.xls. This contains a sample of flights that departed from Des Moines International on one day. For each flight type (General Aviation, Military, Commercial), determine the percentage of flights to each destination city.

    Example: 100 total commercial flights, 10 to Denver, so 10% of all commercial flights go to Denver.

  2. On the Future case drawing, notice that a city is listed twice. Once to the North and once to the South. We will assume that a flight will use the North track 50% of the time and the South track 50% of the time. Fill in the information on the flight graphic. For each flight type, summing all six tracks should give 100%.

Step 3: Running the INM

  1. Choose Start>Transportation>INM

  2. Bug Fix!!! If you have any trouble with errors, try running INM version 6 instead of the Start-Transportation-INM (version 5.1). To use version 6, download a self extracting zip file (save it to C:\user) by Clicking Here. Run the file c:\user\inm6.exe, and after the INM6 copies and expands on your C:\user directory, you can run it by double clicking on the INM icon in C:\user\inm6. Note: if you already have a version 5.1 dataset, you will be prompted to convert to version 6.0 when you try to open your files. Do so.

  3. Start a new study, by choosing File>New Study and create the study in C:\User\. Name the study "354". Choose English Units, when prompted. This creates a directory in C:User called 354 where all your INM files are contained. To save your work, copy this directory to ZIP disk.

  4. When the dialog box appears, Type in your description "354-Partner1,Partner2". Click view airports and select the Des Moines International Airport. When done, Click OK. This includes in the model relevant information about Des Moines (elevation, mean temperature, runway layout, etc.)

  5. The INM contains noise profiles for take-off and landings for many types of aircraft. The ops_arpt.xls listed all the aircraft types departing and arriving Des Moines on our model day.

    Add these aircraft to the study by clicking Setup>Aircraft and Highlight the aircraft from the list below then click the "Include" button(Hold CTRL key to select multiple aircraft).
    737 727200 737300
    BEC58P C130COMSEP
    DC850DC910DC930
    DHC8F4C MD81
    MD83

  6. Next, since we are analyzing two cases, we need to name them in the INM. Click Setup>Cases then go to Edit>Add Record. Fill in the dialog box with Case="Future" and Description="Departure on six tracks". Then select Edit>Commit Record. Add another Case called Case="Current" and Description="Departure on two tracks" by selecting Edit>Add Record

  7. Next, we need to "draw" the departure paths of planes leaving Des Moines International Airport. (The INM can accept actual radar paths or aircraft but since we don't have them we will "draw" in 6 paths.) To do this select Tracks>Input Graphics. To make the labels appear on the runway ends and tracks that you will draw, Click View>Tracks> then check the "Track Label" box and the "Label" box in the runway section. Click OK.

    We will add 6 departure tracks. Departure tracks start on a runway end, continue to the next end, then off on a flight path. Create your tracks to look like this. To begin drawing, select Edit>Add tracks. For a path to the NW, Click on runway end 31R then click on end 13L then off two equivalent runway lengths in line with the runway. If make a mistake drawing hit "ESC" to back up. Double click to end. In the "Add Track Dialog Box" type the name (DEP?) of this track. Click OK, the track should turn blue. Repeat for the remaining five departures paths.

  8. We also need to create arrival paths. We will only need two, since planes generally follow the same arrival track. Arrival tracks originate start out in airspace, then end at the runway end.

    Click here to see picture. Create approach paths like this : Click on airspace directly out from the runway then to runway end 13L then to 31R. Double click to end. In the Add Track Dialog Box type the name of this track "ARR1". Click OK, the track should turn red. Repeat for other approach path from the other direction.

  9. Note: this step is not in the INM software. Using windows explorer, paste the ops_arpt.dbf file into C:\user\354\future and current directories. This file contains the "data" file that tells the INM which aircraft are using the airport and the number of flights.

  10. The INM needs to know how to distribute the aircraft on the departure and arrival tracks. we have calculated, by flight type, the percentage of aircraft using each track. To input this information into the INM we need to assign aircraft to departure and arrival paths for both cases and for the three flight types. We will use the data calculated in Step 1.

    To assign these percentages to the flight operations, Select Ops>Groups Percent. This is tricky input (not user friendly software): Choose the runway end (31R or 13L)to work with (Note: The runway end where the track starts is considered the runway assigned to the departure paths.)

    Select a aircraft type and departure track. Click Edit>Add Record and enter the percentage for that group. Then Edit>Commit Record. Click Edit>Add Record, Change track then fill in the percent. After, you've completed all the percents for one flight type, switch to the next type.
    Don't forget to do arrivals!

  11. The following steps run the model situation for both cases.

  12. Next, select Output>Output Setup. Select Edit>Add Record then type in the name of output ID as "OUT1". Select Metric as "DNL". Select "Future" then Select Edit>Commit Record. Do the same thing for Current, except call the Output ID "OUT2"

  13. Next, select Output>Output Graphics, Select "OUT1" and then OK. Colored graphics will appear on the screen, indicating iso-noise contours.

  14. We will export this file in AutoCAD format so that it can be imported into MapInfo for further analysis. Select File>Export as DXF. Choose Nautical Miles, then Click OK.

  15. Repeat previous two steps for OUT2.

Your study is saved as you complete each step. To save your study, copy the entire 354 directory to a ZIP disk. To reopen your study, select File>Open Study and highlight the Lab6 directory. Do not forget to save the Mapinfo directory to your zip drive.

Step 4: Using MapInfo to Analyze the Output

As stated previously, the output from the INM is only useful if we can overlay the resulting noise contours with other information. For our lab, we will overlay the noise contours with the planned land use around the airport. We will use MapInfo tools to determine the amount of land use inside the 65 DNL contour. We will then compare the two cases.

  1. Start Mapinfo.

  2. The MapInfo file of Landuse and the INM Output file are different in coordinate formats. To overlay the maps, we need to transform the INM file. To do this, Select Table>Import. Find the C:\User\354\Out1 directory and select Autocad (DXF) as the file type. Click on Projection in the Dialog Box. Select "US State Plane Coordinates 1927" as the category. In the Category Members dialog box, Select "Iowa 1402, Southern Zone". Click OK. Next, click on the "Set Transformation" button. Fill in the dialog box like this:
    DXFMapInfo
    Point 1Point 1
    X01956004.8
    Y0559264.8
    Point 2Point 2
    X11962092.2
    Y1565329.5

    Click "OK" and "OK" again. Import the file to C:\User\354\Mapinfo as Inm1.tab. Ignore warning on Autocad blocks.(Hit continue)

  3. Select File>Open Table and Open C:\user\Mapinfo Landsp.tab and Inm.tab. Important! Do not save any changes to Landsp.tab or Inm table, you might corrupt the file!

  4. Find the 65 decibel contour. Use the info tool to find the id number for the contour. It should be ID number 5.

  5. We are interested in the area of land by use type inside the 65 db contour level. We will use the following procedure in MapInfo to split the Landuse polygons inside the 65 db contour level.

  6. Now, we need to create a Table of the land area inside the 65 db contour level. To do this Choose Query>SQL Select. Click this link and fill in the dialog like this Copy this code to dialog box:
    (select obj from inm where id=5) contains landsp.obj
    Note: Replace "inm" with the name of the table you imported in step 2

  7. Next save copy of query you just preformed. Choose File>Save Copy As, choose the query name (most likely query2), click Save As and name (example: area?.tab)

  8. We will check to make sure you saved the correct table. To do this, turn off the Landsp and Inm1 layer in Layer Control dialog box by turning off the "eye symbol". Then Choose File>Open and open the table you just saved. You should see the Landuse inside the 65 db contour level. If you only get contour lines, you saved the wrong item in step 9. Repeat previous step!!

  9. The "Area" of the Landuse in side the 65 decibel contour needs to be updated in table Area?. Currently, the "Area" field still contains the size of the original un-split polygon. Update the table by choosing Table>Update Column. Click this link and fill in the dialog like this! Note: "Table to Update" and "Get Value from Table" require the name of the query you saved in Step 9.

  10. Choose Table>Export and export table Area1 as dbf file you can import into excel to calculate the total affected land uses and use in your report.

  11. Repeat for Case 2 and change file name where necessary.

Step 5: Prepare Report

Prepare a professional, typed report. It is suggested that you follow the following format:
  1. Introduction
  2. Background
  3. Project Description
  4. Study Methodology
  5. Impacts
  6. Mitigation Proposals
  7. Recomendations
  8. Appendices

References (to help you in the report)

Grading

The lab is worth 10% of you entire semester grade (about the same as 13 homework problems):