Why are roads red?
As a gaming geo-scientist, I am fascinated by the rocks and minerals that give real-world terrain its color. This visible geology also determines the hues of our paved roads. From the red dust of Australia in Forza Horizon 3 to the Southwest USA‘s orange vistas in The Crew 2, the natural landscapes we drive through virtually often inspire the roads we drive daily. So why are some roads stained vivid red rather than the more common black asphalt?
Red rocks and reactive aggregates
The aggregate used in road construction consists of crushed gravel and rocks mixed with binding agents. Areas containing granite, quartzite, and sandstone with high iron oxide concentrations naturally tint the aggregate red. Iron oxide, commonly found in volcanic ores, reacts when exposed to air and water to form hematite and rust red in color. Similarly, copper deposits in certain mineral formations also oxidize to give stones a vivid orange-red appearance. When used in aggregate, these vibrant red rocks leave their signature hue on the finished roadway.
Chemical reactions behind red aggregate
Iron oxide:
4Fe + 3O2 → 2Fe2O3
The ferrous iron (Fe) binds with oxygen (O2 ) to produce ferric oxide (Fe2O3), commonly seen as red rust.
Copper oxide:
2Cu + O2 → 2CuO
Copper (Cu) undergoing oxidation to form copper oxide (CuO) also appears red or orange.
Table – Common sources of colorful aggregates
| Region | Mineral Composition | Road Color |
| Hawaii | Iron-rich basalt | Deep red |
| Southwestern USA | Copper deposits | Orange-pink |
| Midwestern USA | Iron oxide shale | Brick red |
Asphalt aging and sun-fading
While underlying aggregate determines the initial color, asphalt roads can also turn red over time due to aging and weathering…
Artificial red road treatments
In addition to natural geological factors, some red roads are artificially created using dyes and paints. Common examples include:
- Bus lanes marked with red asphalt
- Safety zones bordered by red pavement
- Crosswalks painte red
These vivid crimson markings help communicate safe driving messages to more safely navigate our real-world roads.
Red roads in popular video games
As virtual worlds inspire real-world road trips, red roads also feature prominently in the gaming landscapes we love to traverse:
- The rugged Southwestern terrain of hardcore offroad simulator Forza Horizon 3
- The Mars-like red stone of extraterrestrial racer Redout‘s abandoned mines and canyons
- The post-apocalyptic Outback highways in Australian RPG Mad Max
So whether you‘re racing down rural routes in Wisconsin or blazing trails on Mars, the science, history and symbolism of red roads continues to capture our imagination.
Let me know your favorite video game red roads in the comments!
