Most lifelines in Kobe were constructed 20-30 years ago, before the most modern construction standards were put into practice. This elevated highway formed an inverted pendulum that the supporting columns were not able to restrain under shear during seismic shaking. The columns above show a failure typical of somewhat older reinforced concrete structures throughout the world. The vertical steel rods can hold the weight of the structure just fine when that weight is exerted straight down, as usual. During seismic shaking much more steel wound around the rods horizontally can keep the column from breaking apart under the shear forces.
Stronger columns are more expensive to build.
This was particularly likely where the road crossed areas of softer, wetter ground, where the shaking was stronger and lasted longer. Many elevated structures were simply pulled apart by differential movements, here leaving the welded rails and ties suspended. Below one intersection a subway station collapsed, leaving the road above to sink unpredictably for months until it could be excavated. The destruction of lifelines and utilities made it impossible for firefighters to reach fires started by broken gas lines. Large sections of the city burned, greatly contributing to the loss of life.