On public contracts, mobilization is usually its own lump-sum bid item, paid out in the early pay applications rather than tied to a percentage of work completed. A contractor's mobilization costs are real and upfront even though no permanent work has happened yet. Federal contracts formalize this with specific payment procedures for mobilization and preparatory work, generally allocating a defined share of the lump sum to mobilization itself versus other preparatory costs.
For trades that depend on specialized equipment (trenchless boring rigs, pile drivers, cranes, dewatering pumps), mobilization is when that equipment gets ordered, scheduled, and delivered. A full or partial demobilization and re-mobilization mid-project, because of a schedule gap or phased work, can be a real added cost if the contract does not already account for it. Mobilization cost is driven heavily by what equipment a project requires, not just its size. Knowing the specified scope (pipe diameters, trenchless methods, quantities) early enough to plan equipment logistics is valuable for a contractor and for the equipment rental companies whose demand follows those same bid documents. Nonlinear surfaces that scope from the drawings and specs as part of reading a bid package.
