Roberts M – ROUND IN CIRCLES AND BACK AGAIN 2025

Description

Roberts reviews concentric-circles (ortho-radial) schematic transit maps, tracing their history, design logic, and public appeal, and focuses on London versions from 2013 and 2024. Concentric designs offer high coherence—perpendicular crossings, orderly radial structure, and visually striking rings—making them attractive to the public and media. However, they reduce flexibility, often force complex line trajectories, and produce topographical distortion, balance and harmony problems. The author proposes a five‑criterion framework for effective schematic design (simplicity, coherence, topographicity, balance, harmony) and shows concentric maps trade simplicity for coherence. The 2013 London prototype prioritized a perfect orbital loop, requiring rule relaxations that caused station displacements and mixed aesthetic/usability results. Controlled usability tests (notably on a Berlin concentric map) found concentric designs slower and less preferred than optimized octolinear maps, especially for route generation. Roberts concludes concentric maps can succeed only when matched to network structure and when simplicity of trajectories is not sacrificed for visual order; evaluation must be case‑by‑case.