Trends & Indicators of Encroachment

Association of California Airports2007 Annual Fall Conference

September 20, 2007

Lake Tahoe, CA

What is the problem?

Airports are becoming centers of growth, just like rivers and railroads were in previous centuries.

Land in areas adjacent to airports is being developed.

Noise contours have been shrinking, but are projected to increase again with traffic growth.

Are federal and local authorities playing their part in mitigating noise in the community?

Is population encroachment occurring– Inside the DNL 65 contour?– Outside the DNL 65 contour?

And if so, what can be done about it?

Study Purpose

Provide sound scientific understanding of land use and population dynamics around commercial airports in order to create effective land use and noise policies

Identify factors, trends, and patterns of “encroachment”

Assess potential and future land use conflicts

Create effective land use management strategies

Approach

Construct techniques and measures to capture the pattern of residential land uses around airports

Determine the extent to which residential populations are aggregating near airports

Examine the underlying factors influencing “encroachment patterns” near commercial airports

Study the connection between airports, suburbanization, and the spatial expansion of cities

Evaluate strategies to mitigate the land use conflicts

92 Study Airports

Areas of Interest

Land inside the Average Day-Night Sound Level (DNL) 65 dB Contour

Land in the released areas of changing DNL contours

Land adjacent to commercial airports and outside established noise contours

Released Land

Measures of Encroachment

Census

Land Cover

Land Use

Remote Sensing

Spatial Metrics

Zoning

Census

Pop. Housing

-79% -82%

Pop & Noise ChangeNoise Change

NA

-4%

NA 8%

2000 Census Data

Population Change

DNL 65 Contour

1990 Census Data

Baseline

1%

5%1990

2001 -80% -81%

Changes in Population and Housing Inside the DNL 65 Contour at 92 US Airports

 

1990 Census Data 2000 Census Data

Base Case Population Change

Noise LevelPopulatio

nChang

eHousin

gChang

ePopulatio

nChang

eHousin

gChang

e

1990 DNL

55dB to less than 60dB 7960501

NA

3244569

NA

8895745 12%35048

79 8%

60dB to less than 65dB 3934228

1601599 4351974 11%

1716089 7%

65dB to less than 70dB 1484288

593750 1641588 11%

634857 7%

70dB to less than 75dB 348567

135998 357457 3%

132971 -2%

75dB + 65723 20944 57472 -13% 17466 -17%

  Noise Change Population Change

2001 DNL

55dB to less than 60dB 3706768 -53%

1463514 -55% 4075467 10%

1567868 7%

60dB to less than 65dB 1141516 -71%

465317 -71% 1236350 8%

483923 4%

65dB to less than 70dB 309634 -79%

120311 -80% 318188 3%

115785 -4%

70dB to less than 75dB 61238 -82% 19553 -86% 58983 -4% 18121 -7%

75dB + 14042 -79% 4996 -76% 12548 -11% 4508 -10%

Population Housing Population Housing Population HousingNortheast 653,000 234,000 738,000 264,000 13% 13%Midwest 329,000 135,000 346,000 140,000 5% 4%South 365,000 162,000 389,000 163,000 7% 1%West 179,000 80,000 206,000 84,000 15% 5%US 1,525,000 610,000 1,678,000 651,000 10% 7%

1990 2000 Percent Change

Changes in Population and Housing in Released Land

I ncrease Decrease Midwest 14 05 Northeast 13 02 South 19 16 West 14 09 US 60 32

Number of Airports with Housing Increase on the Released Lands

Number of Airports with Changes in Housing Densities between 1 to 10-mile radius from the Airport Reference

Point, 1990-2000

Land Cover

Land Cover

Area (Acres)

1992 2001Chang

e

Undeveloped Land1530

961272

61 -17%

Developed Land

3549

9

6242

0 76%

1992 NLCD vs. 2001 NLCDInside a 10-mile Radius

LandCover as a Function of Noise

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

5055606570

Noise Contour (dB)

Pe

rce

nt

Undeveloped Not Vulnerable Undeveloped Vulnerable

Developed Not Vulnerable Developed Vulnerable

Land Cover as a Function of Distance

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Miles

Pe

rce

nt

Undeveloped Not Vulnerable Undeveloped Vulnerable

Developed Not Vulnerable Developed Vulnerable

Movement of Population-Weighted Center*

1990 2000 Delta

Northeast 2.69 2.60 -0.09

Midwest 3.73 3.51 -0.21

South 3.05 2.76 -0.29

West 3.46 3.35 -0.11

US 3.25 3.05 -0.20

* Inside a 10-mile radius

Recap: General Trends

Little evidence of people moving inside the DNL 65 dB contours – FAA guidelines seem to be effective

Technology has dominated the reduction of overall noise exposure

Evidence that people are aggregating immediately outside the DNL 65 dB contours

Intensification of development occurring around airports

Fifty-percent of the lands within 5 miles of an airport remain undeveloped and vulnerable to population encroachment

What Needs to Happen?

It’s late, but not too late, for FAA to expand guidelines for non-compatible development to areas beyond the DNL 65

Local authorities need to limit non-compatible development outside the DNL 65 contour – establish buffer zones

Establish incentives, such as environmental tax benefits, to limit development in vulnerable areas

What’s Next?

What are the underlying factors influencing “encroachment patterns” near commercial airports?

What is the connection between airports, suburbanization, and the spatial expansion of cities?

Can we predict growth and future conflicts?