Routing compensation can preserve a message after one node fails while leaving delivery vulnerable to joint failures. We analyze matched, identity-closed UDP message outcomes in seven-day vehicular network scenarios from Hohhot. Six message fates distinguish exposure, realized compensation, and residual service effects. The systematic component was more stable across seeds than net damage. Recovery of 6470 successful replacement paths identifies protocol-realized provider dependency. Among 336 evaluated pairs, dependency burden was positively associated with exposure-conditioned irreducible pair loss J₂ (Spearman 0.516; Kendall 0.445); the fixed matched-control group-mean contrast had a date-cluster bootstrap median of 0.0066 and a 95% percentile interval [0.0024, 0.0116]. A separate triple-world analysis found residual losses beyond constituent pair-world service-loss sets: 61 of 64 evaluated triples met the stable-positive J₃ criterion. Of 1315 formal J₂ message instances, 1081 had identifiable constituent paths; mechanism proportions apply only to that subset. At 100–200 m, compensation and the pooled dependency–J₂ association persisted, but magnitudes and date-level consistency changed materially. The conclusions are partially range-sensitive, sample-conditional, and non-causal.

Roadside unit (RSU) planning requires evidence about when vehicles may encounter candidate sites and whether a shortlist repeatedly covers the same vehicles. This study treats potential vehicle–site contact opportunities—not observed communication sessions or network traffic—as short-horizon vehicle-to-infrastructure (V2I) demand. Seven days of Hohhot taxi and bus trajectories, comprising more than 40 million records, were aggregated into 15 min panels for 1317 bus-stop-derived candidate sites. Training-only vehicle-transition relations augmented LightGBM forecasting, and a permuted-graph control assessed the value of the mobility structure. Historical vehicle-population overlap then informed set-level site screening, which was evaluated by future unique-vehicle coverage. Graph-informed forecasts showed modest improvements over tabular and permuted-graph models, while a historical time-of-day baseline remained stronger at 60 min. At the primary 100 m spatial footprint and 30 min horizon, overlap-aware screening improved unique-vehicle coverage by approximately 10% across shortlist budgets. Temporal-gap sensitivity and dependence-aware inference qualify the forecasting evidence. These results provide a data-driven screening basis for prioritizing candidate RSU sites before detailed feasibility, communications, and engineering assessment.