Wallroads

Wallroads are a proposed form of urban transport infrastructure in which roadways are integrated into vertical surfaces such as building facades, retaining walls, or interior courtyard walls. In theory they create additional travel corridors in dense cities by utilizing space that is otherwise unused. Walls can host exterior lanes attached to towers, along city boundaries, or interior walls within courtyards, and may employ cantilevered decks, supported rails, or other load-bearing arrangements. Vehicles travel on paved tracks or surfaces and are guided or stabilized by systems such as rails, maglev, or incline mechanisms; automated control is typically envisioned to manage slope, spacing, and safety.

Design and engineering considerations include structural load paths, wind and seismic resilience, drainage, maintenance access, and fire safety. Accessibility requires integrated vertical circulation for passengers and service personnel, often via lifts or stair cores. Because maintenance occurs on vertical surfaces, protective coatings, corrosion control, and weatherproofing are central concerns.

Development status: wallroads exist mainly in speculative design, theoretical studies, and pilot proposals rather than in completed projects. Proponents emphasize space efficiency, potential weather protection at the ground level, and new urban vistas. Critics argue that high construction costs, complexity of egress in emergencies, and ongoing maintenance challenges limit near-term viability.

Variants and applications include exterior façade lanes on dense tower clusters, vertical lanes within city walls, and hybrid systems combining pedestrian and vehicular paths with sensors and automation. Real-world precedents, such as skybridges and elevated walkways, inform wallroad concepts but do not constitute wallroads as defined here.

See also: elevated roads, skybridges, vertical cities.