Dirt Roads Used by Heavy Vehicles (image) Cell Press Share Print E-Mail Caption Even dirt roads through national parks are used by heavy vehicles, as shown in Katavi. Credit Current Biology, Caro et al. Usage Restrictions Credit Required Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.