roadbed
Rails rest here
The roadbed is the foundation layer on which a road or railroad track is built.
For roads, it's the prepared surface of compacted soil or gravel beneath the pavement.
For railroads, it's the layer supporting the ties and ballast: The crew repaired a section of damaged roadbed.
The term emphasizes the engineered base rather than the visible surface.
Soil layer supporting pavement
- gravelLoose small rock fragments
- aggregateCombined sum total
- ballastShip stability material
- compactionReducing volume through pressure
excavation · embankment · fill · grading · drainage · tamping · layering · earthwork
Petroleum-based paving material
- concreteSolid building mixture
- gravelLoose small rock fragments
- aggregateCombined sum total
- ballastShip stability material
macadam · bitumen · tar · fill · riprap · geotextile · sand · clay
Marks showing passage
- ballastShip stability material
- tiesConnections or neckwear
- sleepersUnactivated spies or surprise hits
- railsGuiding metal bars
gauge · spikes · alignment · grade · trestle · right-of-way · crossing · maintenance
Reducing volume through pressure
- firmnessResistance to deformation
- durabilityResistance to wear
- load-bearingSustaining structural mass
- settlementResolved dispute or colony
erosion · drainage · reinforcement · resilience · subsidence · support
subgrade
Soil layer supporting pavement
compaction · excavation · embankment · fill · grading · drainage · tamping · layering · earthwork · geotextile
asphalt
Petroleum-based paving material
ballast · macadam · bitumen · tar · fill · riprap · geotextile · sand · clay · limestone
tracks
Marks showing passage
rails · gauge · spikes · alignment · grade · trestle · right-of-way · crossing · maintenance · cinders
compaction
Reducing volume through pressure
- firmnessResistance to deformation
- durabilityResistance to wear
- load-bearingSustaining structural mass
settlement · erosion · drainage · reinforcement · resilience · subsidence · support
pavement
Hard road covering
carriageway · median · crown · grade · slope · drainage · curb · gutter · overlay · resurfacing
- model trainsmodel trains, train set, train sets, electric trains, electric train
- model railroadsbenchwork, mainline, siding, spur, turnout
- railroad trackrail, rails, crosstie, crossties, sleeper
- roadbedtrackbed, subgrade, subbase, base course, ballast
- roadshighway, highways, freeway, roads, freeways
- structureshouse, bridge, buildings, dome, building
roadbedsuperstructure
Construction above the base
rails · tracks · rolling stock · pavement · road surface