Case Study: Balancing Freight Savings, Inventory Costs and Working Capital

 

Choosing a transportation mode based solely on freight rates can lead to suboptimal supply chain decisions. A lower freight cost may generate additional inventory, increase working capital requirements and expose the business to longer replenishment cycles.

This case evaluates whether shifting low-to-medium-value automotive components from express road freight to intermodal Ro-Ro and rail transportation creates a sustainable financial advantage.

1. Problem Definition

A company imports 120 tons of raw materials and components per week from Europe to its manufacturing plant. The company is evaluating two transportation alternatives.

Option A — Express Road Freight

·       Freight cost: €225/ton

·       Transit time: 4 days

·       Safety stock: 1 day

·       Total inventory coverage: 5 days

Option B — Intermodal Ro-Ro + Rail

·       Freight cost: €150/ton

·       Transit time: 9 days

·       Safety stock: 4 days

·       Total inventory coverage: 13 days

The transported material has an average value of €7,500 per ton. The annual inventory carrying cost rate is assumed to be 20%, including the cost of capital, warehousing, insurance and obsolescence.

The operating model assumes 52 weeks of annual demand and stable average consumption.

The key question: Does the freight cost reduction justify the additional inventory and working capital required by the slower transportation mode?

2. Quantitative Cost Analysis

2.1 Annual Freight Cost

Annual transportation volume: 120 tons/week × 52 weeks = 6,240 tons/year

Cost component	Express Road	Intermodal
Freight rate	€225/ton	€150/ton
Annual volume	6,240 tons	6,240 tons
Annual freight cost	€1,404,000	€936,000

 

Annual freight savings: 6,240 × (€225 − €150) = €468,000

Intermodal transportation reduces annual freight expenditure by €468,000, equivalent to a 33.3% reduction in the freight rate. However, freight savings alone do not represent the total economic benefit.

2.2 Inventory Impact

Average daily consumption: 120 ÷ 7 = 17.143 tons/day

The inventory requirement is estimated using the sum of transit time and safety stock.

Inventory metric	Express Road	Intermodal
Inventory coverage	5 days	13 days
Inventory quantity	85.71 tons	222.86 tons
Inventory value	€642,857	€1,671,429

 

Additional inventory required: 17.143 × (13 − 5) = 137.14 tons

Additional inventory investment: 137.143 × €7,500 = €1,028,571

The intermodal option therefore requires approximately €1.03 million more working capital to support the longer replenishment cycle. This is a balance-sheet and liquidity impact, not an additional freight expense.

2.3 Annual Inventory Carrying Cost

Annual carrying cost per ton: €7,500 × 20% = €1,500/ton/year

Cost component	Express Road	Intermodal
Inventory quantity	85.71 tons	222.86 tons
Annual carrying cost	€128,571	€334,286

 

Incremental inventory carrying cost: 137.143 × €1,500 = €205,714/year

2.4 Net Annual Logistics Cost Benefit

Financial impact	Annual amount
Freight savings	+ €468,000
Additional inventory carrying cost	− €205,714
Net annual cost benefit	+ €262,286

 

Under the base-case assumptions, intermodal transportation delivers an estimated annual logistics cost advantage of approximately €262,286. This result assumes that the two freight rates are comparable on a total landed transportation basis and that all relevant incremental inventory costs are captured in the 20% carrying cost rate.

3. Sensitivity Analysis

The economic advantage depends on both the value of the transported material and the inventory carrying cost rate. The following scenarios retain the same annual volume, transportation rates and eight-day inventory coverage difference.

Net annual savings from choosing intermodal transportation (€)

Product value per ton	20% carrying cost	30% carrying cost	40% carrying cost
€5,000	+330,857	+262,286	+193,714
€7,500	+262,286	+159,429	+56,571
€10,000	+193,714	+56,571	−80,571

 

The results demonstrate that intermodal transportation remains economically attractive for the €7,500/ton material in all three scenarios, although the advantage declines significantly as carrying costs rise.

At a product value of €10,000/ton and a 40% carrying cost rate, the additional inventory burden exceeds the freight savings, producing an estimated annual disadvantage of €80,571.

These results illustrate why transportation mode selection should be differentiated by material characteristics rather than applied uniformly across the supply chain.

4. Working  Capital and Financial Interpretation

The additional working capital requirement is approximately €1.03 million.

Incremental savings-to-working-capital ratio: €262,286 ÷ €1,028,571 = 25.5%

This is an incremental savings-to-working-capital ratio. It should not automatically be interpreted as ROIC or as a risk-free investment return.

The calculation compares annual cost savings with additional inventory capital, but it does not constitute a complete investment appraisal. A formal financial assessment should distinguish operating cost savings from financing costs and avoid double-counting the cost of capital if it is already included in the inventory carrying rate.

Management should also evaluate the company's liquidity position, cash conversion cycle, available financing and the opportunity cost of the additional capital tied up in inventory.

5. Discussion

Based on the base-case results, intermodal transportation is a financially attractive option for the selected material category, subject to operational validation. I would recommend a segmented transportation strategy rather than a blanket shift to slower modes.

·       First, segment materials by value, demand stability and criticality. Low-value, predictable and non-critical materials are generally stronger candidates for consolidated transportation. High-value or production-critical components may require faster and more reliable replenishment.

·       Second, validate service-level requirements. The additional eight days of inventory coverage must be sufficient to protect production against demand volatility, transit-time variability and disruption risks. Safety stock should be calculated using actual demand and lead-time variability, not solely fixed assumptions.

·       Third, validate the total landed cost. Terminal handling, drayage, customs delays, damage exposure, emergency shipments and any additional intermodal charges must be included where applicable.

·       Finally, assess the working capital constraint. The €262,286 annual cost advantage is meaningful, but the company must be able to support the additional €1.03 million inventory investment without compromising liquidity or other strategic priorities.

Conclusion

The lowest freight rate does not necessarily deliver the lowest total supply chain cost. Equally, the fastest transportation mode does not always create the greatest economic value.

The optimal decision balances transportation expenditure, inventory carrying cost, service performance, risk and working capital.

The management principle is simple: Optimize the total cost of serving production, not the cost of transportation in isolation.