This article describes a feature in the first Apocalypse Rising
Roadblocks are wedge-shaped concrete slabs placed on most roads by either the police or military in the early stages of the apocalypse. It is unknown why exactly they were used, since any vehicle could easily get past them by driving onto the grass alongside the road. However they could have been used to stop zombies, and used in different towns and cities towns to quarantine off the different streets to prevent civilians who are infected from spreading the infection. However this tactic evidently failed resulting in the much larger Military Barricades being set up.
Uses and Tips
Roadblocks cannot spawn anything.
They are useful for jumping over if you are being chased by a zombie.
Makeshift roadblocks are useful for people trying to prevent vehicle movement. Just throw down some building supplies, maybe arrange them heightwise or lengthwise and you just made yourself a roadblock.
Roadblocks do not spawn on dirt roads, and rarely on grass, the only exception is at Bump Flatts.
When you are driving at night, always leave your lights on and make your screen brighter so that you can avoid roadblocks, as they are the same color as the road.