Constraint-Based Bounding of a Stated Volume Target
ABSTRACT
Official statements target 10 million tonnes of Trans-Caspian freight against a 2025 base of 5.2 million. This simulation bounds the outcome by constraint rather than by demand, identifies Caspian vessel availability and hydrology as binding, and produces two scenarios with distinct policy implications.
1. Method
This is a constraint-based bounding exercise. It asks what throughput is physically achievable given identified capacity limits and announced procurement schedules, rather than what throughput demand would support. Constraint bounding is the appropriate method where the historical demand series is short, where demand has been driven by an exogenous political shock, and where the supply side is characterised by long-lead-time assets — all three of which apply here.
2. Baseline and target
Trans-Caspian freight volumes were approximately 500,000 to 700,000 tonnes before 2022, rising to roughly 1.5 million tonnes in 2022, 2.7 million in 2023, 4.5 million in 2024 and 5.2 million in 2025. The growth rates were 114 percent, 80 percent, 67 percent and 16 percent respectively, showing marked deceleration in the most recent year.
During a Turkish presidential visit to Kazakhstan in May 2026, the Kazakh president stated that 10 million tonnes was reachable in the near term, with some projections placing it as early as 2027. Reaching 10 million by 2029 from the 2025 base requires compound annual growth of approximately 18 percent sustained over four years, against realised 2025 growth of 16 percent.
3. Constraint accounting
Fixed land infrastructure is not binding. The Baku–Tbilisi–Kars railway was upgraded in 2024, following reconstruction of its 184-kilometre Georgian section, from 1 million to 5 million tonnes of annual capacity. The port of Alat is expanding from 15 to 25 million tonnes. Aktau handles 3.2 million tonnes of dry cargo and 12.5 million tonnes of oil annually, with a container hub added in June 2025 projected to raise capacity by 100,000 twenty-foot equivalent units. Poti processed over 600,000 containers in 2025. Turkish terminal capacity along the alignment substantially exceeds realised throughput.
Three constraints bind. Caspian vessel availability is the most severe: roll-on/roll-off and container tonnage on a landlocked sea cannot be redeployed from other basins, the existing fleet is ageing, and procurement remains at feasibility stage. Rolling stock and traction is the second: Kazakhstan Railways has awarded a 4.2 billion dollar contract for 300 locomotives and plans 574 additions by 2029, with an electric freight locomotive programme scheduled to 2028. Modal transfer time is the third: delays concentrate at rail-to-port and port-to-rail interfaces, and transit time has fallen from 38–53 days to 18–23 with a stated ambition of 14–18, most of the remaining reduction sitting at the interfaces.
4. The hydrological constraint
A fourth constraint has begun to bind and is absent from most planning documents. Declining Caspian Sea levels reduce draught availability at ports and on approach channels. Rail tank car ferry transport on the Baku–Kuryk route has already fallen 22 percent and wagon transport 10 percent.
This constraint is qualitatively different from the others because it is not investible in the ordinary sense. Dredging extends the operating envelope at specific locations at recurring cost; it does not reverse a basin-wide decline driven by evaporation and reduced inflow. It also acts selectively on the heaviest and most draught-sensitive cargo, which is bulk and mineral traffic — precisely the category that critical raw materials strategies depend on.
5. Scenario 1: fleet delivered
Assumptions: roll-on/roll-off and container tonnage commissioned and operational by 2027; locomotive deliveries proceed on the announced schedule; interface transfer times hold at current levels or improve; Caspian levels decline no faster than the recent trend.
Under these conditions the constraint set supports 9 to 10 million tonnes by 2029. The Baku–Tbilisi–Kars capacity of 5 million tonnes becomes binding for the rail-borne share, which implies that either a portion of the flow moves by other routes into Türkiye and Europe or that a further upgrade is required within the horizon. Alat’s expansion to 25 million tonnes accommodates the maritime leg.
The observable early indicator for this scenario is a signed vessel construction or acquisition contract with a delivery schedule, which as of mid-2026 had not been announced.
6. Scenario 2: fleet lags
Assumptions: vessel procurement remains at feasibility stage through 2027; locomotive deliveries proceed but cannot be utilised beyond the Caspian bottleneck; Caspian level decline continues at or above the recent rate.
Under these conditions throughput plateaus at 6 to 7 million tonnes. The plateau is not a demand outcome — demand may well exceed it, given the redundancy premium created by maritime chokepoint risk — but a physical one, and it would manifest as rising congestion, lengthening transit times and rising unit costs rather than as visibly unmet demand. Bulk and mineral cargo would be displaced first by the draught constraint.
7. Interpretation and the commercial question
Both scenarios remain small relative to maritime flows, which are measured in billions of tonnes annually. Unit costs reinforce the point: 2,500 to 3,250 dollars per forty-foot equivalent container via the corridor against 2,599 to 3,121 on the northern route through Russia and 1,500 to 2,000 by sea. The corridor sells transit time — 18 to 23 days against 28 to 40 by sea — and political neutrality, at a price premium.
Its strategic value is therefore option value under chokepoint risk. The 2026 closure of the Strait of Hormuz priced that option rather than creating it, and the pricing is visible in shipper interest rather than in the corridor’s cost structure, which did not change.
For Türkiye the volume question is secondary to the capture question. At either 7 or 10 million tonnes, the contribution to Turkish output depends on the share of associated insurance, trade finance, customs processing, warehousing, maintenance and terminal handling performed in Turkish jurisdiction. That share is set by regulatory and industrial policy, and it is not measured by tonnage.
8. The capture question
A volume projection understates the analytical question for Türkiye, because tonnage crossing a territory and value accruing within it are different quantities. At 7 million tonnes with minimal domestic service capture, the corridor contributes transit fees and limited terminal handling revenue. At the same tonnage with substantial capture, it contributes insurance and reinsurance premiums, trade finance margin, customs processing revenue, warehousing and cold chain fees, maintenance and repair activity, and the legal and arbitration work that follows multimodal contracts.
The distinction is measurable and is not currently measured. The indicators that would show whether capture is occurring are the share of corridor-related insurance written by Turkish underwriters, the volume of corridor trade finance booked by Turkish banks, the number of corridor customs declarations processed on Turkish platforms, and terminal handling volumes at Turkish facilities on the alignment. None of these appears in corridor reporting, which is conducted almost entirely in tonnes.
This matters for policy sequencing. If capture is the binding variable, the marginal return on regulatory and financial sector measures exceeds the marginal return on additional physical capacity, and the current investment emphasis is inverted relative to where value is actually determined.
9. Limitations
The exercise bounds by constraint and therefore says nothing about whether demand will materialise to fill the available capacity. It assumes announced procurement schedules are met, which procurement schedules frequently are not. It treats hydrological decline as continuing at the recent rate, which is an extrapolation rather than a projection. It does not model the effect of the north–south corridor or the trans-Russian northern route as competing options, both of which would draw traffic under different geopolitical conditions. And it does not assign probabilities to the scenarios.
SOURCES
Kazakh Ministry of Transport and Trans-Caspian International Transport Route volume series, 2021–2025.
World Bank (2023) The Middle Trade and Transport Corridor: Policies and Investments to Triple Freight Volumes and Halve Travel Time by 2030.
Caspian Policy Center (2026) ‘How to Maximize the Middle Corridor’, June 2026 edition, including rolling stock and port capacity data.
Jamestown Foundation (2026) ‘Middle Corridor Makes Progress Toward Operational Reality’, April 2026.
Azerbaijan Caspian Shipping Company, Baku–Kuryk ferry and wagon transport data.
EY Kazakhstan, Trans-Caspian International Transport Route cost and transit-time analysis.
Coordinating Council on Transit Freight of Azerbaijan, Baku–Tbilisi–Kars capacity data.
Furkan Mahmut Tameroglu