The Climate Road—A Multifunctional Full-Scale Demonstration Road That Prevents Flooding and Produces Green Energy

This paper presents a multifunctional full-scale demonstration road, the Climate Road,
which combines climate adaptation and mitigation in a single system. The Climate Road is located
at Hedensted, Denmark and is 50 m long and 8 m wide, and the depth of the roadbed is 1 m. Half
of the Climate Road, i.e., 25 m, is paved with permeable asphalt and the remaining 25 m with
traditional asphalt. All surface water drains into the roadbed, which stores up to 120 m3 of water,
either directly through the permeable asphalt or by drain grates. In addition, 800 m of geothermal
pipes are embedded in the roadbed, distributed over four 200 m w-loops, two buried 1 m below
the asphalt and two similar loops at 0.5 m depth. The Climate Road was tested from May 2019 to
May 2021. In the project period, a total precipitation value of 1654 mm was recorded, the mean
temperature was 9.3  C and the most intense rainfall was 40.3 mm/30 min. The long-term infiltration
performance of the permeable asphalt shows that the overall infiltration capacity slowly reduces. The
reduction can be hindered, but not completely prevented, with annual restorative cleaning. After
two years of operation, the Climate Road still, by a large margin, fulfils the recommendations of
the infiltration capacity of 97.2 mm/h for the vast majority of the road section. The total volume
reduction capacity is estimated to be between 15 and 30%. Based on an analysis of 61 single rain
events, the event detention time is found to range between 10 and 130 min, with an average of 35 min.
During the project period, the Climate Road produced a total of 98 MWh for a nearby kindergarten,
with an average coefficient of performance (COP) of 3.1.