Revisiting Cost-Benefit Analysis in Transport: Travel Time Savings, Stated Preference Studies, and the Decline of Benefits Over Time

Kurzfassung

Cost-Benefit Analysis (CBA) remains the benchmark for transport appraisal, but its disproportionate reliance on monetized travel time savings (TTS) overstates benefits, privileges highly mobile and affluent users, and can legitimize environmentally unsustainable investments while neglecting equity, reliability, uncertainty, and long-term spatial dynamics. We reconceptualize TTS as dynamic, socially differentiated, and often transitory, and reveal the sensitivity of outcomes by quantifying elasticities of TTS with respect to key parameters. Methodologically, we expose persistent weaknesses of stated-preference valuation and propose alternatives that integrate heterogeneous value-of-time models, distributional welfare functions, and accessibility-based indicators. We further show how induced demand, rebound effects, and land-use adjustments erode long-term benefits, and demonstrate the potential of dynamic modelling—including agent-based simulations and big-data-driven estimation to capture behavioural adaptation and spatial change. We argue for shifting from static, mobility-based CBA toward accessibility-centred, dynamic, and equity-weighted appraisal frameworks that strengthen robustness and transparency, provide clearer guidance for investment decisions, and address key blind spots in current practice. With this paper we advance discussion how TTS should be incorporated into transport infrastructure appraisal and address key blind spots in existing CBA applications.