Modelling Motorway Emissions v2

Modelling Motorway Emissions

28 November 2012

Mark ChapmanTechnical Director (Air Quality)

2Bureau Veritas Presentation

Introduction

► Roads → Carriageways → Lanes

► Emission Profiles

Background, Default Assumptions, Lane by Lane Approach

► Model Verification and Adjustment Factors

► Impact Assessment

Managed Motorways, Concentration Profiles, Influence on Results, Considerations and Caveats


Roads Carriageways Lanes

► Roads Single Line Emission Source

W1 E1


Roads Carriageways Lanes

► 3 Lane Carriageway vs. 3 Lane by Lane

WHS W3 W1 CR E1 E3 EHSW2 E2

CRWHS EHSE2 E3E1W3 W2 W1


Emission Profiles: Background

► Local CCTV Observation Explained: Part 1

Asymmetrical distribution of Flow across carriageway:

• 25% of Lane 1 (Inside Lane) total

• 29% of Lane 2 (Middle Lane) total

• 46% of Lane 3 (Outside Lane) total

Asymmetrical distribution of HGVs across carriageway:

• 5% of Lane 1 (Inside Lane) total

• 42% of Lane 2 (Middle Lane) total

• 53% of Lane 3 (Outside Lane) total




HGV influence on average speed of the lane

• HGVs restricted to 56 mph (90 kph)

• LGVs/Cars always obey the speed limit at 70 mph (112 kph)!

Because disproportionate emissions from HGVs compared to LGVs/Cars

• Emissions distribution across the carriageway also asymmetrical


0%

10%

20%

30%

40%

50%

60%

WHS W3 W2 W1 CR E1 E2 E3 EHS

Pe

rce

nta

ge

Lane

3 Lane Carriageway 3 Lane by Lane


► 3 Lane Carriageway vs. 3 Lane by Lane




3 Lanes

• Volume and composition of vehicles were unevenly distributed across all lanes

4 Lanes

• Volume and composition of vehicles were also unevenly distributed across all lanes

• Vehicles tended to remain in the same lane when a 4th Lane was available

• Shift in vehicles from Lane 3 to Lane 4 when available

• Assumed to be because vehicles were getting off at the next junction


0%

10%

20%

30%

40%

50%

60%

WHS W3 W2 W1 CR E1 E2 E3 EHS

Pe

rce

nta

ge

Lane

3 Lane Carriageway 4 Lane Carriageway

Emission Profiles: Default Assumptions

► 3 Lane Carriageway 4 Lane Carriageway


Emission Profiles: Lane by Lane Approach

► 3 Lane by Lane 4 Lane by Lane


Model Verification and Adjustment Factors

Annual Mean NO2 Carriageway Model Setup

Lane by Lane Model Setup

Monitored Total 55 (@ 10m)

Monitored Background 15

Monitored Road Component (NO2) 40

Monitored Road Component (NOx) 101.9

Modelled Road Component (NOx) 65.5 67.5

Adjustment Factor 1.56 1.51 (3.2% reduction)

Adjusted Modelled Total 55


Impact Assessment: Managed Motorways

► Aim: Increase motorway capacity to manage increased demand for use

► CALR4 Continuous All Lane Running

4 Lanes [3 + Hard Shoulder] Open Continuously

► HSR Hard Shoulder Running

Managed use of Hard Shoulder during peak demand periods

Typically AM Peak, Inter-Peak and PM Peak; c.12 hrs of operation


37

42

47

52

57

62

67

72

77

82

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

Co

nce

ntr

ati

on

(u

g/m

3)

Distance from Kerb (m)

3 Lane Carriageway CALR4 Carriageway HSR Carriageway

Impact Assessment: Concentration Profiles

► Carriageway


37

42

47

52

57

62

67

72

77

82

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

Co

nce

ntr

ati

on

(u

g/m

3)

Distance from Kerb (m)

3 Lane by Lane CALR4 Lane by Lane HSR Lane by Lane

Impact Assessment: Concentration Profiles

► Lane by Lane


Impact Assessment: Influence on Results

Carriageway Model Setup


Predicted Concentration

3 Lane (Do Minimum)Lower Concentration Higher Concentration

(More Exceedences)

Predicted Concentration

4 Lane (Do Something)

Higher Concentration

(More Exceedences)(Mitigation potentially

harder to achieve)

Lower Concentration

(Fewer Exceedences)(Mitigation potentially

easier to achieve)

Predicted Impact Magnitude

Higher Magnitude(Scheme Causes More

Exceedences)

Lower Magnitude(Scheme Causes Fewer

Exceedences)


Impact Assessment: Influence on Results

Number of Properties Exposed

Distance from Motorway Kerb

(m)

Carriageway Model Setup


10 10 +51.0 +44.1

5 20 +17.7 +15.8

1 30 +2.7 +2.5

Score elsewhere in network -62.4

Net Score+9

Overall Worsening

0Overall Neutral


Considerations and Caveats

► Influence of exhaust emission height Default vs. Lane by Lane variation - Adjustable within ADMS-Roads?

► Investigate influence coupled with temporal profiling: AM, IP, PM and OP traffic characteristics adjustment

► Dependent on local lane by lane traffic characteristics More survey data required

► Anyone seeking to Model Motorways for the Highways Agency should seek guidance from HA Air Quality Advisor


Highways Agency: Significance Criteria Update

► Highways Agency Business Objective Net Score

“The Highways Agency will not progress a major scheme which would worsen the situation overall regarding compliance with the EU Limit Value”

Highways Agency Business Plan 07-08

► Evaluation Criteria: Sum of the change in predicted concentration [impact] at relevant receptors,

where exceedence of the EU Limit Value is predicted in either Do Minimum (Without Scheme) or Do Something (With Scheme) Scenario



► Review of the Highways Agency's Approach to Evaluating Significant Air Quality Effects Issued 07 September 2012

Version: 1.1 (Final)

Deadline for ‘comments’ closed on 5 October 2012



► DRAFT In Advance of Publication of Interim Advice Note (IAN) Updated air quality advice

(supplementary guidance) on the application of the test for evaluating significant effects; for users of DMRB Volume 11, Section 3, Part 1 (HA 207/07) ‘Air Quality’

• Includes supporting spreadsheet

• Future IAN to be used forthwith on relevant projects in England, where air quality assessments are undertaken, and where such projects have yet to be submitted for statutory process, including the Determination of the need for a statutory Environmental Impact Assessment (EIA)



► Need for Updated Advice?

A (technical) review of the HA’s approach to evaluating significant air quality impacts for the purposes of Environmental Impact Assessment (EIA)

• To reflect national planning policy changes (National Planning Policy Framework) whist still meeting requirements of the EIA Directive (2011/92/EU)

In light of this review, the HA is developing a new approach to evaluating significant air quality impacts

Modelling Motorway Emissions v2

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