# Transport Constraints as Design Inputs The physical dimensions of a modular data center are not primarily determined by IT requirements — they're determined by what you can ship. **Hard constraints:** - **Width:** 3.5m max (road transport limits) - **Length:** 20m max without police escort (standard truck/trailer) - **Sea freight:** ~1 month from factory (e.g., Taiwan/Europe) to Nairobi - **Weight:** Must fit within road and crane limits for last-mile delivery **Why these are design inputs, not afterthoughts:** If you design the optimal thermal layout first and then discover it's 4m wide, you've wasted months of engineering. Transport constraints define the physical envelope before anything else. Rack count, aisle width, cable routing, cooling unit placement — all of these must fit within the shipping box. **Practical implications:** - Rack depth and aisle configuration are bounded by the 3.5m width constraint - Longer MDC modules (approaching 20m) avoid the cost of police escorts but limit deployment flexibility - Sea freight timeline (~1 month) means you need to complete factory testing well before the target deployment date - Site preparation (foundations, power, network) must happen in parallel with factory build, not sequentially **The principle:** Know your shipping constraints before you start designing. The container that ships the MDC *is* the MDC. If it can't fit on a truck, it doesn't exist. --- See also: [[Factory Pre-Testing and CFD Validation]] | [[Modular Data Centers MoC]]