Surface Temperature and State of the Road in Several Monitored Points Along the Piedmont Highway Network
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Reproducing surface road temperature by means of a land surface numerical scheme Nicola LOGLISCI (1) , Riccardo BONANNO (1) , Claudio CASSARDO (2) (1) Regional Agency for Environmental Protection - Arpa Piemonte, Torino - Italy (2) Department of General Physics “A. Avogadro”, University of Torino – Italy (corresponding author: [email protected] ) ABSTRACT Reproducing surface road temperature is a crucial factor for winter road management. In fact, extreme cold winters as well as rain or snow falling on the roads need expensive road management opera in terms of human and technologic resources. To avoid unnecessary and expensive actions, a new parameterization of the porous asphalt (PAP, Porous Asphalt Parameterization) has been implemented in the UTOPIA model. Porous asphalt represents the most used kind of asphalt for highways construction . The goal of this numerical study is to reproduce surface temperature and state of the road in several monitored points along the Piedmont highway network. UTOPIA-PAP has been validated against surface road measurements made at six different sites during the period running between January 2007 and January 2011 showing a good estimation of the surface road temperature and state. These good performances of UTOPIA-PAP have a surplus value. In fact, the better estimation of the surface temperature and state leads to a better estimation of the energetic and hydrologic balance. PURPOSE Autostrade S.p.a. UTOPIA model station with porous asphalt ARPA weather stations •numerical modelling of the surface road The University of TOrino land Process Interaction in Atmosphere model (UTOPIA) is a 1-D multilayer model computing energy, momentum and temperature and state Massino Visconti nord water exchanges between atmosphere and land. The processes in UTOPIA •better estimation of the PBL Courmayeur Ponte Yalla Someraro are described in terms of physical fluxes and hydrological state of the Mont de la Saxe (Pre St Didier for temperature) Romagnano Sesia land . •early warning system for road winter Ghemme The physical processes: The hydrological processes: management Casale Monferrato nord • Radiative fluxes; • Evapotranspiration processes; AVAILABLE DATA Casale Monferrato • Momentum flux; sensible and • Snow accumulation and melting; Viadotto Villastellone latent heat fluxes; partitioning • Rainfall, interception, Operational data from two networks: Santena Banna of latent heat into canopy, soil infiltration and runoff; and snow components; • Soil hydrology, including water 1. Autostrade per l’Italia S.p.a. Viadotto Franco Romano Fossano • Heat transfer in a multi-layer transfer in a multi-layer soil soil or lake 2. ARPA Piemonte Fig. 1. The network used for modelling. UTOPIA-PAP (Porous Asphalt Parameterization) UTOPIA setting Define soil property for the porous asphalt Asphalt surface state 1 cm Porous Suggested literature values Hydraulic 6 cm Egw 5 cm asphalt ηηη ∆M (m) = ∆ tP- 1. Soil porosity s gw/i ρ 2 -1 w 2. Saturated hydraulic conductivity Kηηηs (dm s ) 10 cm Gravel Egw > 0 evaporation 3. Soil matrix potential at saturation Ψηηη (cm) s Egm < 0 condensation 4. b parameter Sensitivity test at Romagnano Sesia 2b+3 -b The transition from water Mgw to ice η η Initial values K =K w Ψ = Ψ w M and vice versa depends on the η η s η η η s η gi s s presence of ice in the first soil layer In situ soil Thermal (asphalt layer). type divided -3 -1 435 cm 1. Volumetric soil heat capacity ρρρc (Jm K ) into 8 more -1 -1 Surface water/ice fraction: Final values 2. Thermal conductivity KT (Wm K ) layers M Surface parameters R=gw/i ≤ 1 ααα gw/i 1. Albedo Mg,max 2. Emissivity εεε Mg,max = 0.00048 m Fig. 2. Vertical structure of soil column 3. Roughness length z0gm (m) RESULTS SENSITIVITY TEST : Romagnano Sesia highway station, 2.5 km from Ghemme ARPA station RMSE = 2.71 RMSE = 1.68 RMSE = 3.79 RMSE = 2.10 RMSE = 2.21 RMSE = 1.45 R2 = 0.9493 R2 = 0.9747 R2 = 0.9642 R2 = 0.9752 R2 = 0.9151 R2 = 0.9543 Fig. 3. Scatter plot: Utopia vs. Observation Fig. 4. Scatter plot: Utopia vs. Observation Fig. 5. Scatter plot: Utopia vs. Observation surface temperature ( °C) surface Minima ( °C) surface Maxima ( °C) SOME OTHER SITES ASPHALT SURFACE STATE 1) Casale Monferrato nord highway station, 4 km from Casale Monferrato ARPA station • Periods with simulated snow coverage Massino Visconti nord highway station on asphalt surface has been removed RMSE = 1.92 RMSE = 2.17 RMSE = 1.40 to avoid wide discrepancies in the R2 = 0.9704 R2 = 0.9781 R2 = 0.9630 statistical analysis. In fact in the real case the snow cover is removed from the asphalt because of snowplow a) vehicles and traffic. On the contrary, in the simulation, the snow cover keeps the asphalt layer warmer than the real one . 6) 8) 10) b) • Also salt spreading operations in 2) Massino Visconti nord highway station, 7 km from Someraro ARPA station winter periods, not implemented in the Utopia model, can cause some RMSE = 2.63 RMSE = 3.05 RMSE = 1.96 discrepancies in the statistical 2 2 2 R = 0.9494 R = 0.9643 R = 0.9239 analysis. In fact the latent heat c) release due to ice formation keeps the asphalt layer warmer compared to the Figure a) shows the simulated asphalt surface state in the winter same with a lower freezing point . period 2008 /2009 at Massino Visconti highway station . Blue line represents the surface water fraction, the red one the ice • Another possible cause of fraction that occurs when the surface temperature drops below discrepancies could be also the the freezing point (see figure b). In presence of snow cover 7) 9) 11) influence of the traffic on the asphalt (figure c), the ice fraction decreases and disappears when the Fig. 6,7: Surface temperature time series Fig. 8,9: scatter plot Fig. 10,11 scatter plot: maximum and thermal balance, not implemented in asphalt surface is totally covered by snow. the Utopia model. minimum temperatures Conclusions and future developments Acknowledgements We wish to thank the Autostrade per l’Italia S.p.a for providing the asphalt surface temperature data . References In this work we implemented and tested the UTOPIA-PAP (Porous Asphalt Parameterization) to simulate the porous asphalt • Joby D. Carlson, ‘Pervious concrete: questions answered’, National center on SMART Innovations for Urban surface temperature and state (water or ice fraction) . Statistical analysis with Romagnano Sesia highway station data shows Climate+Energy, Arizona State University, Presented to : The City of Glendale and the Arizona Cement Association, that UTOPIA-PAP simulates in a very good way the asphalt surface temperature . January 17, 2007 • Y. Aoki, R. Sri Ravindrarajah, and H. Khabbaz 2009, ‘Effect Of Fly Ash Performance Of Pervious Concrete’, 9th Statistical analysis at the other sites shows even satisfactory results, but less good than those of Romagnano Sesia. This is ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete and 10th ACI mainly due to the greater distance between the highway station and the correspondent ARPA weather station in all the International Conference on Recent Advances in Concrete Technology and Sustainability Issues, pp. 511-520. • M. A. Eusuf and T. Asaeda, 1998, ‘Heating effects on urban thermal environment’, Journal of Civil Engineering, The other sites considered . Another possible cause may be also some little differences in thermal and hydrological properties Institution of Engineers, Bangladesh, Vol . 26 , No . 2, pp 173 -190 . between the Romagnano Sesia asphalt (the one used to do the sensitivity test) and the one of other sites (especially for • V. Masson, C. S. B. Grimmond and T. R. Oke, 2002, ‘Evaluation of the Town Energy Balance (TEB) scheme with direct measurements from dry districts in two cities’, Journal of Applied Meteorology, Vol. 41, pp 1011-1026. those located in a different highway). • L. P. Crevier and Y. Delage, 2001, ‘METRo: A new model for road-condition forecasting in Canada’, Journal of Applied A future development can be the implementation and testing of the traditional asphalt parameterization. Meteorology, Vol. 40, pp 2026-2037. • L. Bouilloud and E. Martin, 2006, ‘A coupled model to simulate snow behavior on roads’, Journal of Applied Another future goal is to implement an operative chain able to forecast the asphalt conditions (temperature, surface state, Meteorology and Climatology, Vol . 45 , pp 500 -516 . presence of snow cover…) in different points of the Piedmont highway network. • C. Jansson, E. Almkivist and P-E. Jansson, 2006, ‘Heat balance of an asphalt surface: observations and physically- based simulations’, Meteorological Applications, Vol. 13, No. 2, pp 203-212..