Week 5 p2

Question 1

What are traffic noise sources ?

Answer 1

Engine, exhaust system, and transmission - loudest when traffic not free flow, varies with engine speed
Tyre-road surface interaction - higher for free flow, noise depends on vehicle speed and surface material

Question 2

How do barriers help with noise abasement ?

Answer 2

Walls of earth berms separate highways and homes
Reduce noise by 10-15 dB or half loudness
Need to block ‘line of site ‘
Topography accounted for (build barrier to top of hill)

Question 3

How is reducing traffic speed helpful for noise control ?

Answer 3

Reduces road noise
Helps improve traffic flow

Question 4

How does planting vegetation help with noise control ?

Answer 4

Planting a 60m width of dense vegetation can half noise levels but lots of vegetation needed for significant effect

Question 5

How can vehicle restrictions help with noise control ? What are some cons ?

Answer 5

London Lorry Control Scheme restricts HGVs to use major roads only between 2300-0700
- can divert paths increasing fuel consumption and emissions
- can increase daytime use of HGVs and lead to congestion

Question 6

What is sound insulation used for ? What does it require to work?

Answer 6

To restrict traffic noise in home. Relies on windows being closed so might need air conditioning
Better sound insulation usually means better thermal insulation

Question 7

What are some aircraft noise sources ?

Answer 7

Jet flap interaction
Jet noise reflection from wing
Jet noise scattering
Jet mixing noise
Fan noise

Question 8

Why has further expansion of Heathrow been delayed ?

Answer 8

Due to noise being a major environmental issue associated with airports

Question 9

What is the requirement for airports if they produce >50,000 movements per day?

Answer 9

The EU requires a Noise Action Plan to be made

Question 10

What are some limitations put on airports by local authorities to deal with noise ?

Answer 10

• caps on total flights
• restrictions of night flights

Question 11

What are some aircraft noise abatement options?

Answer 11

1. Relocation away from populous areas (offshore)
2. Air traffic management (ATM) measures
3. Noise charges to encourage shift to new aircrafts
4. Noise insulation for buildings

Question 12

What is the continuous descent approach (CDA) for noise control in flights? (Air traffic management measure)

Answer 12

Plane glides down as opposed to dropping in steps and thrusting forward
Reduces required engine thrust, fuel consumption, and noise

Question 13

What is the idea behind runway alteration? (ATM)

Answer 13

Aircraft takes off and lands in wind, minimising ground speed
Gives communities periods without flight
Limited by wind conditions

Question 14

How steep are aircrafts usually when setting off ? When are they steeper ? Is steepness an air traffic management measure?

Answer 14

3-3.5 deg
5.5 deg in London to avoid obstacles
Can be used to reduce noise

Question 15

What are the benefits of noise preferential routing ? (ATM)

Answer 15

Avoids flying over more populous areas - less affected

Question 16

What are the benefits of reducing thrust for takeoff and climb?

Answer 16

Reduces fuel consumption, noise, and engine deterioration

Question 17

What is the idea behind the displaced threshold (ATM) ?

Answer 17

Reducing length of runway
Touch down point further down runway for arrivals
Can reduce safety buffer and might require changes to taxi ways and additional taxi time

Question 18

What is permitted for larger planes?

Answer 18

Louder noise in takeoff, flyover and approach

Question 19

How are aircraft noise levels measured ?

Answer 19

Three measurements at approach, takeoff, and flyover are made and summed

Question 20

How does Heathrow base its noise charges ?

Answer 20

On size (larger = higher cost)
On whether plane is travelling at day or night (night = more expensive)

Question 21

How are noise charges assessed based on certification noise ?

Answer 21

Noise charge = unit noise rate (cost) x noise units
Depends on airport and how much problem noise is at airport.

Question 22

How are noise units assessed ?

Answer 22

Noise units = 10^((La-Ta)/10) + 10^((Ld-Td)/10)
La = certified approach noise
Ld = certified noise during departure (average of lateral and flyover measurements)
Ta= noise threshold at approach (89 EPNdB)
Td= departure noise threshold (82 EPNdB)
EPN- expected perceived noise

Question 23

When is dG applicable for cortn method?

Answer 23

For uphill flow on single carriageway

Question 24

When applying shield correction which corrections can be neglected ?

Answer 24

diff(c)
diff(d)