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On the Capacity of Future Lane-Free Urban Infrastructure

Patrick Malcolm, Klaus Bogenberger

Abstract

In this paper, the potential capacity and spatial efficiency of future autonomous lane-free traffic in urban environments are explored using a combination of analytical and simulation-based approaches. For lane-free roadways, a simple analytical approach is employed, which shows not only that lane-free traffic offers a higher capacity than lane-based traffic for the same street width, but also that the relationship between capacity and street width is continuous under lane-free traffic. To test the potential capacity and properties of lane-free signal-free intersections (automated intersection management), two approaches were simulated and compared, including a novel approach which we call OptWULF. This approach uses a multi-agent conflict-based search approach with a low-level planner that uses a combination of optimization and simple window-based reservation. With these simulations, we confirm the continuous relationship between capacity and street width for intersection scenarios. We also show that OptWULF results in an even utilization of the entire drivable area of the street and intersection area. Furthermore, we show that OptWULF is capable of handling asymmetric demand patterns without any substantial loss in capacity compared to symmetric demand patterns.

On the Capacity of Future Lane-Free Urban Infrastructure

Abstract

In this paper, the potential capacity and spatial efficiency of future autonomous lane-free traffic in urban environments are explored using a combination of analytical and simulation-based approaches. For lane-free roadways, a simple analytical approach is employed, which shows not only that lane-free traffic offers a higher capacity than lane-based traffic for the same street width, but also that the relationship between capacity and street width is continuous under lane-free traffic. To test the potential capacity and properties of lane-free signal-free intersections (automated intersection management), two approaches were simulated and compared, including a novel approach which we call OptWULF. This approach uses a multi-agent conflict-based search approach with a low-level planner that uses a combination of optimization and simple window-based reservation. With these simulations, we confirm the continuous relationship between capacity and street width for intersection scenarios. We also show that OptWULF results in an even utilization of the entire drivable area of the street and intersection area. Furthermore, we show that OptWULF is capable of handling asymmetric demand patterns without any substantial loss in capacity compared to symmetric demand patterns.
Paper Structure (11 sections, 8 equations, 8 figures, 1 algorithm)

This paper contains 11 sections, 8 equations, 8 figures, 1 algorithm.

Table of Contents

  1. Introduction
  2. State of the Art
  3. Analytical Derivation of Saturation Flow
  4. Description of OptWULF
  5. Object Representation
  6. CBS Planner
  7. Spatial Conflict Resolver
  8. Temporal Planner
  9. Scenario Description
  10. Simulation Results
  11. Conclusion

Figures (8)

  • Figure 1: Conceptual rendering of a lane-free intersection.
  • Figure 2: Theoretical saturation flow of a lane-free street with various narrow vehicle penetration rates (colored lines, in 10% increments) and a minimum lateral gap of [0.1]m between vehicles, assuming a [2]s gross headway. The lane-based saturation flow (assuming a lane width of [3.2]m) is shown in black.
  • Figure 3: Representation of intersection, trajectories, and conflicts in OptWULF. (a) Plan view. (b) Spatial alignment view. (c) Temporal view. Not to scale.
  • Figure 4: OptWULF special cases for intersection conflict definition. (a) Perpendicular conflicts. (b) Merging conflict. (c) Shared origin.
  • Figure 5: Example conversion of temporal window constraints into free time windows and the determination of feasible free time window combinations.
  • ...and 3 more figures