Porous asphalt is a road material that allows rainwater to infiltrate through the top layer of a road in an effort to handle stormwater on the spot rather than through drainage piping and infrastructure. Good design of porous asphalt requires understanding the relationship between porosity, permeability, as well as durability. In this work, the pore space is modelled via imaging and digital construction of the total and connected pore space. Then, the infiltration behaviour through the pore space is simulated via lattice Boltzmann modelling, which allows for the calculation of saturated-permeability values. Spatial coarsening tests are performed to assess its impact on permeability results. It is in understanding the top-to-bottom connected pores that the permeability of the asphalt can be better assessed, leading to improved design of porous asphalt.