AGi32 allows 3-dimensional obstructions or reflecting surfaces to be considered in roadway calculations. This is not simply illuminance, but all roadway metrics will consider the shadowing and reflecting properties of objects in the environment. This allows realistic luminance calculations in applications where reflected or obstructed light is a factor such as over/under-passes and tunnels. AGi32 is the only program with this capability.
Starting with the most basic scenario, it is a simple operation to add a roadway surface to a 2-dimensional model to enable AGi32’s visualization capability. In the image below we have placed a single polygon object at Z=0 with asphalt reflectance of 10%. The reflectance is actually immaterial at this point as all reflected light is lost without additional surfaces to redirect it back down toward the pavement. It does however, allow a rendered view of the roadway as we now know the diffuse luminance of the pavement surface due to direct light. In terms of the relationship to the actual roadway calculations, it is set as surface type: “Pavement Surface– Direct Flux Only” using the Surface Edit command and has no impact on the results of this calculation.
Object added for pavement to facilitate rendering
In a more detailed analysis, an overpass and its obstructive and reflective properties can be considered in the computation of all roadway grids placed in the environment. The critical procedural element within the software is to define all object surfaces as “Roadway Contributors.”
Using AGi32’s visualization capability it is easy to assess the need for supplemental lighting under the overpass (below).