At the beginning of the game, the only new item you can craft is the cobblestone path. 2 stone bricks are required for crafting 4 pieces of cobblestone path. Cars driving on cobblestone have their friction reduced by 15% and characters walk on it 45% faster.
RoadWorks also adds limestone, which is a new kind of ore used to make concrete. Once the Hydraulic Cement research is done, limestone can to be burned into quicklime, which is then mixed with water and stone in a chemical plant to make concrete. At the moment, concrete is only used in pavement crafting, but eventually it will also be used in bridge construction and possibly other recipes. Concrete pavement needs 4 concrete blocks for crafting and speeds up both cars and players by 30%. Note that you do not need the Oil Refining technology to build the chemical plants needed to create concrete.
The last kind of placeable surface in RoadWorks is the asphalt road. To make it, you must first research Road Networking, after which you can turn heavy oil to asphalt in chemical plants and then use 4 of the newly created asphalt pieces to make the asphalt road. Cars receive 45% friction reduction on asphalt roads but player characters walk only 15% faster on them.
Once you research Advanced Automobilism, you will be also able to manufacture high-octane fuel by putting together four cubes of solid fuel and a piece of sulfur. High-octane fuel is specialized for usage in car engines and raises acceleration by 35%. However, it doesn't last as long as solid fuel when used in vehicles and is much less efficient, as the 2 pieces of solid fuel used to craft it last quite a bit longer when used as fuel.
Advanced Automobilism also unlocks car instruments. When you enter a car after this research is done, a small window will appear in the top left corner showing you your current speed and the amount and kind of fuel currently loaded in the car.