| Appendix 3.7 | Detailed Calculation of In-Tunnel Air Quality | ||||||||||
| for the Full Enclosure at Castle Peak Road viaduct | |||||||||||
| - | Normal speed | ||||||||||
| Tunnel Parameter | |||||||||||
| Tunnel length (m), L | = | 175 | |||||||||
| Tunnel height (m), H | = | 5.5 | |||||||||
| Tunnel width (m), W | = | 20 | |||||||||
| Tunnel size (m2), At | = | H * W | |||||||||
| 110 | |||||||||||
| Equivalent diameter (m), dt | = | (4*At/p)^0.5 | |||||||||
| 11.83455 | |||||||||||
| Effective length of the tunnel (m), Le | = | L + 2*3*dt | |||||||||
| 246.0073 | |||||||||||
| Emission Data | |||||||||||
| Traffic Breakdown (%) | |||||||||||
| Traffic flow (veh/hr) | Petrol | L.Diesel | H.Diesel | ||||||||
| Tunnel traffic | 2410 | 43 | 32 | 25 | |||||||
| Q (veh/hr) | 1030 | 781 | 600 | ||||||||
| Petrol | L.Diesel | H.Diesel | |||||||||
| Emission Factor (g/km) - EURO3 | 0.71 | 1.54 | 6.8 | ||||||||
| Weighted NOX E.F. (g/km/veh) | = | 2.494227 | |||||||||
| NO2 emission factor per unit length (g/m/s), w | = | 0.000334 | |||||||||
| Vehicle Data | |||||||||||
| Nominal dimensions of vehicles are given in Transport Planning and Design Manual, Vol. 2 as: | |||||||||||
| W | H | L | |||||||||
| Pertol | 1.7 | 1.5 | 4.6 | ||||||||
| L.Diesel | 2.1 | 1.6 | 5.2 | ||||||||
| H.Diesel | 2.5 | 4.6 | 16 | ||||||||
| HGV | |||||||||||
| Nominal cross-sectional area (m2) | = | (1.7*1.5*(0.43)+(2.5*4.6*0.25)+(2.1*1.6*0.32) | |||||||||
| = | 5.039427 | ||||||||||
| Number of lanes per direction, nl | = | 2 | |||||||||
| Equivalent cross-sectional area for each direction (m2), Av | = | 10.07885 | |||||||||
| Equivalent diameter of vehicle (m), dv | = | (4*Av/p)^0.5 | |||||||||
| = | 3.582291 | ||||||||||
| Traffic density (traffic flow /s), N | = | 0.669444 | |||||||||
| Average vehicle speed (m/s), v | = | 70 km/hr | |||||||||
| = | 19.44444 | ||||||||||
| Head to head distance on a lane (m), l | = | 2*nl*v/N | |||||||||
| = | 116.1826 | ||||||||||
| Diffusion Parameters | |||||||||||
| Reynolds number, Re | = | (v*dv)/s | where s = 15.6*10^-6 | ||||||||
| = | 4465106 | ||||||||||
| According to Figure 16 (Ohashi and Koso) | |||||||||||
| Since | l / dt | = | 9.81724 | ||||||||
| D / (N * dt^2 * Re^0.13) | = | 0.4 | |||||||||
| Longitudinal | |||||||||||
| diffusion coefficient (m2/s) , D | = | 0.4 * (N * dt^2 * Re^0.13) | |||||||||
| = | 274.5085 | ||||||||||
| Maximum Concentration of NO2 | |||||||||||
| Cmax (µg/m3) | = | w * Le^2 / (8 * D * At) | |||||||||
| (without background) | = | 83.66387 | |||||||||