1. the foundation structure of a road, typically consisting of layers of gravel, stone, or other materials that support the pavement
2. the prepared ground or foundation on which railroad tracks are laid
Usage: railroad terminology

Examples

• The construction crew spent weeks preparing the roadbed before laying the asphalt.
• Heavy rains washed out part of the roadbed, making the highway impassable.
• The railroad company replaced the old wooden ties and repaired the roadbed.
• Engineers tested the soil to ensure the roadbed could support heavy truck traffic.
• Gravel and crushed stone form the base layer of most roadbeds.
• The train derailed when the roadbed shifted during the earthquake.