Longitudinal profile optimization for roads within an eco-design framework

Abstract

This paper proposes a methodology to optimize the longitudinal profile of roads according to either an energy consumption or Global Warming Potential (GWP) criterion calculated for both construction and operation phases. For the construction phase assessment, this methodology is based on a earthworks model that computes the geometric differences between the natural terrain and the longitudinal road profile and moreover uses environmental data validated with real experiments. The operation phase is assessed by simulating traffic over a ten-years period. Traffic simulations are based on vehicle dynamic models, also validated with real experiments. The optimization problem is set up in a finite dimensional optimization. A case study illustrates this methodology. By taking into account actual traffic measurements, the optimized profile decreases by 6 % the total primary energy consumption and by 8 % the GWP.

Vehicle energy savings by optimizing road speed-sectioning

“…Road as a variable to decrease energy demand in its use phase may be studied in the design stage, in order to compare projects [15], or, for a given project, to optimize the longitudinal profile [16]. However, these studies do not focus on gains achievable when roads have yet been build.…”

Slope Optimization (or “Sloop”): Customized Optimization for Road Longitudinal Profile Eco-Design

“…x k−1 < x k (5) with k varying from 1 to n. Moreover, the last intersection must be far enough from the beginning of the actual road to link both straight lines by a circle with a compatible radius. This is expressed by the following inequality where x end is set by the optimization process user (x end has to be set before the end of the studied profile, x end < x e ).…”

“…The GWP assessment of the construction phase has been fully described in [5]. Let's recall herein the main features to provide an overview.…”

“…Within the eco-design framework, a methodology called PEAM (for Project Energy Assessment Method) was specifically developed to assess transportation projects according to the geometry of the infrastructure taking into account construction and operation phases i.e., the planned traffic impact. PEAM was then applied to either evaluate High-Speed Line projects [3], road speed-sectioning [4] or to assess the longitudinal profile i.e., slopes of road project [5].…”

“…In [5], the authors implement a local optimization called Sloop for Slope Optimization. The starting point is a profile proposed on the drawing board.…”