The issue of a peak in world oil supply has become a mainstream concern over the past several years. The petroleum geology models of post-peak oil production indicate supply declines from 1.5% to 6% per year. Travel requires fuel energy, but current transportation planning models do not include the impacts of constrained fuel supply on private travel demand. This research presents a method to assess the risk to activities due to a constrained fuel supply relative to projected unconstrained travel demand. The method assesses the probability of different levels of fuel supply over a given planning horizon, then calculates impact due to the energy supply not meeting the planning expectations. A new travel demand metric which characterizes trips as essential, necessary, and optional to wellbeing is used in the calculation. A case study explores four different urban forms developed from different future growth options for the urban development strategy of Christchurch, New Zealand to 2041. Probable fuel supply availability was calculated, and the risk to transport activities in the 2041 transport model was assessed. The results showed all the urban forms had significantly reduced trip numbers and lower energy mode distributions from the current planning projections, but the risk to activities differed among the planning options. Density is clearly one of the mitigating factors, but density alone does not provide a solution to reduced energy demand. The method clearly shows how risk to participation in activities is lower for an urban form which has a high degree of human powered and public transport access to multiple options between residential and commercial/industrial/service destinations. This analysis has led to new thinking about adaptation and reorganization of urban forms as a strategy for energy demand reduction rather than just densification.