Editorial project overview

When a Traffic Solver Invents a Jam

Can final shock-grid alignment make a cell-average refinement gate misleading while fixed operational event and queue metrics still expose numerical bias?

Reproducible studyUpdated 30 Aug 2026
Technical figure from When a Traffic Solver Invents a Jam
A reviewed research figure synchronized from the private technical workspace. The original aspect ratio and labels are preserved.

Editorial overview

The literature gate returned REFRAME because LWR shocks, entropy selection, Godunov and cell-transmission methods, numerical diffusion and high-resolution comparisons are mature. The defensible contribution is a frozen replication-extension diagnostic with a preserved null, not a new solver or a real-traffic claim.

Read When a Traffic Solver Invents a Jam for the exact shock derivation, grid-alignment mechanism, four operational diagnostics, complete twelve-case result, failure record, reproduction signature and claim boundary.

Key findings

  • The exact backward shock speed is -0.05 and the fixed sensor arrival is 4.0; all twelve numerical cases remain finite, bounded and conservative.
  • At N=50, Godunov final cell-average L1 error is about 1.37e-11 because the final shock aligns with a cell boundary, while the threshold arrival remains 0.517647 late.
  • Arrival delay, transition width and threshold-defined queue errors improve with grid refinement, but the frozen strict final-L1 gate fails for both Godunov and Rusanov.

Limitations

  • The evidence covers one dimensionless Greenshields shock, one sensor, one threshold, one CFL and four grids.
  • No empirical road, detector, calibration, travel-time forecast, safety conclusion or transport-policy recommendation is involved.
  • The study derives no modified-equation coefficient, proves no new theorem and makes no universal ranking of finite-volume schemes.

Technical record

Detailed source, calculations, generated figures, and reproduction instructions are maintained in a private technical workspace. Public articles contain only manually reviewed interpretation and approved figures.

Version history

2026-08-30 — Curated overview reviewed against repository evidence.