This report contextualises Engineering models for the calculation of Differentiated Track Access Charges (D-TAC) with existing D-TAC schemes in UK and Switzwerland, and the Swedish proposed D-TAC model by Öberg. The focus is to review and critically assess Andersson’s proposed updates and simplifications to Öberg’s model. Two major focus areas are addressed: Marginal Cost Recalibration, where previous econometric model values are challenged, highlighting issues such as overestimated costs, improper inclusion of snowplough expenses, and maintenance inefficiencies. A revised cost structure is proposed: 0.0130 kr/ton-km + 2.35 kr/train-km, shifting some vehicle-dependent costs to train-dependent costs. Vehicle Classification Simplification, where the proposal is to simplify marginal costs dependent only on i) average axle load and ii) the vehicle’s steering ability, aiming for a system easier for Trafikverket (TRV) to use. The price would be first proportional to the average axle load of the train to the power of 2,5, plus a value from the steering-induced rail damage costs, where the vehicles would be categorized into classes (R1, R2, S) based on their steering performance. This second cost component directly introduces incentives for the adoption of track-friendly vehicles.