A428 Black Cat to Caxton Gibbet improvements TR010044 Volume 6 6.3 Environmental Statement Appendix 5.3: Air quality assessment methodology Planning Act 2008 Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009 26 February 2021 A428 Black Cat to Caxton Gibbet improvements Environmental Statement Appendix 5.3: Air quality assessment methodology Infrastructure Planning Planning Act 2008 The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009 A428 Black Cat to Caxton Gibbet improvements Development Consent Order 202[ ] Appendix 5.3: Air quality assessment methodology Regulation Reference: Regulation 5(2)(a) Planning Inspectorate Scheme TR010044 Reference Application Document Reference TR010044/APP/) 6.3 Author A428 Black Cat to Caxton Gibbet improvements Project Team, Highways England Version Date Status of Version Rev 1 26 February 2021 DCO Application Planning Inspectorate Scheme Ref: TR010044 Application Document Ref: TR010044/APP/6.3 A428 Black Cat to Caxton Gibbet improvements Environmental Statement Appendix 5.3: Air quality assessment methodology Table of contents Chapter Pages 1 Air quality assessment methodology 1 1.1 Model setup 1 1.2 Model outputs 4 1.3 Model post processing 28 1.4 References 37 Table of Plates Plate 1-1: Wind rose diagram for Luton Airport, 2015 .......................................................... 3 Plate 1-2: Comparison of modelled NOX against monitored NOX in the ‘General’ zone prior to adjustment ..................................................................................................................... 35 Plate 1-3: Comparison of modelled NOX against monitored NOX in the ‘General’ zone post- adjustment ......................................................................................................................... 36 Table of Tables Table 1-1: General ADMS-Roads model conditions ............................................................ 1 Table 1-2: Summary meteorological data for Luton Airport, 2015 ........................................ 3 Table 1-3: Public exposure receptors modelled in the local air quality assessment for the operation of the Scheme ...................................................................................................... 4 Table 1-4: Ecological receptors modelled in the local air quality assessment .................... 24 Table 1-5: Monitoring sites excluded from model verification ............................................ 30 Table 1-6: Monitoring sites used in model verification ....................................................... 32 Table 1-7: Verification statistics ......................................................................................... 34 Table 1-8: Verification details at monitoring sites ............................................................... 34 Planning Inspectorate Scheme Ref: TR010044 Application Document Ref: TR010044/APP/6.3 A428 Black Cat to Caxton Gibbet improvements Environmental Statement Appendix 5.3: Air quality assessment methodology 1 Air quality assessment methodology 1.1 Model setup General inputs The parameters used within ADMS-Roads (Ref 1) are described in Table 1-1. Table 1-1: General ADMS-Roads model conditions Variables ADMS-Roads model inputs Emissions NOX, PM10 Emission factors IAN 185-13 Speed Band Emission Factors v2.3 Surface Roughness at source 0.5m Minimum Monin-Obukhov length for stable 10m conditions Meteorological data Hourly sequential data from Luton Airport in 2015 Receptors Selected representative receptors only. Identified from a combination of OS Mastermap and Addressbase data Model Output Road contributions to long term annual mean NOX and PM10 concentrations Additional input file Fac file for time varying emissions A latitude of 52 degrees was input to the site data properties. This determines times of sunrise and sunset for each day throughout the year, which in turn affects stability calculations. A surface roughness coefficient of 0.5m (representative of parkland and open suburbia) was applied across the study area. The surface roughness is important in the approximation of turbulent conditions within the atmospheric boundary layer and thus in the estimation of pollutant concentrations at receptors. Minimum Monin-Obukhov length (to reasonably limit the occurrence of very stable atmospheric conditions) was defined as 10m at both the meteorological site and the dispersion site (representative of small urban areas). This parameter limits the occurrence of very stable boundary layer conditions (i.e. when the air is still) to a degree that is appropriate to the general land-use. In general, the potential for very stable conditions is lowest in large urban areas where the ‘heat island’ effect promoting turbulent motion in the boundary layer is strongest. Planning Inspectorate Scheme Ref: TR010044 1 Application Document Ref: TR010044/APP/6.3 A428 Black Cat to Caxton Gibbet improvements Environmental Statement Appendix 5.3: Air quality assessment methodology Emissions rates The emission rates used in the local air quality modelling were derived from the Design Manual for Roads and Bridges (DMRB) LA 105 (Ref 2). In accordance with LA 105 the competent experts for traffic applied the following procedure: a. Analysis of the performance of modelled traffic speeds on individual road links compared against observed speeds on the same road links. b. Adjustment, where required, of modelled traffic speeds on individual road links to better reflect observed speeds; this is known as the ‘speed pivoting’ approach. c. Assignment of individual road links into a speed-banding category by road type. d. Manual adjustment, where required, of assigned speed band where changes in speed did not justify a change in speed band (e.g. speed changes of less than 5kph) or where a speed band change was considered by the traffic modellers to not reflect a valid Scheme impact. Hourly emission rates were then calculated as follows: a. Weekday morning peak (AM), inter peak (IP), evening peak (PM), off peak (OP) hourly flows (in terms of light duty vehicles (LDV) and heavy-duty vehicles (HDV)) and associated speed band for each road link were obtained from the traffic model for each period. b. The competent expert for traffic confirmed which hours the relevant traffic model periods apply to, as follows: i. AM: 07:00 – 10:00 (3 hours). ii. IP: 10:00 – 16:00 (6 hours). iii. PM: 16:00 – 19:00 (3 hours). iv. OP: 19:00 – 07:00 (12 hours). c. Emission rates for each time period were calculated using the using the traffic flow, %HDV, speed band and road type using the “IAN 185-13 Speed Band Emission Factors v2.3” spreadsheet tool. d. Emissions for each time period were input into the ADMS-Roads model and a “fac” file used to specify which hourly emission rate should be applied for each hour of the day. Meteorological data Hourly sequential meteorological data for 2015 for the Luton Airport meteorological station were used (Ref 2). The parameters required by the model included: date, time, wind direction (angle wind blowing from), wind speed (at 10m above ground level), surface air temperature (degrees Celsius), and cloud cover (oktas – or eighths of sky covered). Summary data for the site is presented in Table 1-2 and the wind rose for Luton Airport is presented below in Plate 1-1), indicating that the dominant wind direction for 2015 was from the southwest. Planning Inspectorate Scheme Ref: TR010044 2 Application Document Ref: TR010044/APP/6.3 A428 Black Cat to Caxton Gibbet improvements Environmental Statement Appendix 5.3: Air quality assessment methodology \\Ukcrd1fp001\ukcrd1fp001-v1ie\projects\general\AirPlate 1-1: Wind rose diagram Quality\Projects\A428 for Luton Airport, Black Cat\Modelling\Model_setup\Stacked 2015 method\Luton_15.met 350° 0° 10° 340° 800 20° 330° 30° 320° 40° 600 310° 50° 300° 60° 400 290° 70° 200 280° 80° 270° 90° 260° 100° 250° 110° 240° 120° 230° 130° 220° 140° 210° 150° 200° 160° 190° 180° 170° 0 3 6 10 16 (knots) Wind speed 0 1.5 3.1 5.1 8.2 (m/s) Table 1-2: Summary meteorological data for Luton Airport, 2015 Parameter Value Annual precipitation total (mm) No data Calm (%) 1.6 Low wind speeds >0 ≤1.5 m/s (%) 6.4 Maximum Wind Speed (m/s) 18.0 Average Wind Speed (m/s) 4.7 Most frequent Wind Direction (deg) 210 Maximum Temperature (°C) 33.0 Minimum Temperature (°C) -4.0 Average Temperature (°C) 10.5 Average cloud (Octas) 4 Planning Inspectorate Scheme Ref: TR010044 3 Application Document Ref: TR010044/APP/6.3 A428 Black Cat to Caxton Gibbet improvements Environmental Statement Appendix 5.3: Air quality assessment methodology 1.2 Model outputs Public exposure receptors Table 1-3 presents details of the human health receptors included in the air quality model for the operation phase. The locations of these receptors are shown in Figure 5.3 of the Environmental Statement [TR010044/APP/6.2]. Table 1-3: Public exposure receptors modelled in the local air quality assessment for the operation of the Scheme ID X Y Location Class type Local authority Central Bedfordshire R1 498217 241457 The Woodlands Residential Council Central Bedfordshire R2 498746 241560 Whittington Crescent Residential Council Central Bedfordshire R3 499126 241745 Goodman Croft Residential Council Central Bedfordshire R4 499346 241758 Arundel Road Residential Council Central Bedfordshire R5 499707 242084 Barkers Piece Residential Council Central Bedfordshire R6 499919 242484 Lower Shelton Road Residential Council Central