The Hierarchy of Provision is a list of traffic interventions which was intended to help highways designers create better conditions for cycling. It was first created in the mid-1990s, and features prominently in The DfT's LTN 2/08 Cycle Infrastructure Design.
Unfortunately it has not led to better conditions for cycling, principally because it does not specify what kinds of treatments should be employed on certain categories of road and streets. In practice it allows highway engineers to get away with making slight improvements for vehicular cycling, while tinkering at the edges with footway conversions.
The Hierarchy of Provision is increasingly falling out of favour, replaced with a network-based approach that examines the kind of road or street in question, determines its function, and then applies a suitable treatment to make it safe and attractive for cycling - be that separate cycleways, or filtered permeability to reduce motor traffic levels.