Transportation planning optimization uses mathematical models to decide how freight moves: which orders share a truck, which mode and carrier each shipment takes, and the route and stop sequence, at the lowest total cost that still meets delivery windows. It works best when it is planned together with replenishment and fulfillment, because the quantities those plans release decide how full the trucks can be.
What Decisions Does a Transportation Plan Include?
A shipper’s transportation plan for the next day or week comes down to a handful of linked decisions:
- Load building: which orders, pallets and products go on which vehicle, within weight, volume, pallet-position and product-compatibility limits.
- Consolidation: combining orders across customers, days or origins so fewer, fuller vehicles move the same volume.
- Mode selection: full truckload, less than truckload, parcel, intermodal or another mode, priced against actual tariffs.
- Carrier and fleet allocation: private fleet, dedicated contract fleet or third-party carriers, each with its own cost structure and capacity.
- Routing and scheduling: stop sequence, delivery time windows, driver hours and vehicle availability for multi-stop routes.
Each decision changes the others. A consolidated load may need a different mode, and a different mode changes which time windows can be met. A planner working through them one at a time, in a spreadsheet, settles each decision in turn and rarely goes back to the earlier ones. An optimization model looks at all of them together and searches for the combination with the lowest total cost.
Load Building and Consolidation
Load fill drives much of transportation cost, because a truck costs nearly the same to run half full as full. Load building assigns orders to vehicles under physical rules: maximum weight and volume, pallet footprint, stacking limits, layer rules, temperature zones and products that cannot travel together. Good load building also follows the sequence in which stops will be served, so the driver does not have to unload the back of the trailer to reach the first delivery.
Consolidation widens the pool of orders a load can draw from. Orders for neighboring customers can share a multi-stop route. Orders due on Thursday can ride on Wednesday’s truck if the customer accepts early delivery. On the inbound side, milk runs collect from several suppliers on one route instead of sending a partial truck to each. Our inbound logistics guide to fleet utilization covers supplier-side consolidation in detail.
Mode and Carrier Selection
Mode selection compares the cost and service of each way a shipment could move. A full truckload is cheapest per pallet when the load is full. LTL and parcel cost more per unit but avoid paying for empty space. Intermodal rail can cut cost on long lanes when transit time allows it. The right answer depends on the shipment’s size, distance, due date and the tariffs actually in force, which change by lane and season.
Carrier and fleet allocation adds a capacity question on top. A private or dedicated fleet has a fixed number of vehicles and drivers. Using them well comes first, with third-party carriers covering overflow. When the fleet is short, the model decides which shipments go to contract carriers and at what cost.
Routing, Time Windows and Multi-Stop Plans
Vehicle routing problems are among the oldest and most studied problems in operations research. The planning version for shippers adds the constraints that make them hard in practice: customer delivery windows, unloading times, driver working hours, vehicle types that certain sites cannot accept, and routes that span more than one day.
Routing interacts with load building. A route that serves five stores in sequence needs those stores’ orders on the same truck in the right order. Separating the two steps tends to produce full trucks with bad routes, or good routes with half-full trucks. Solving them together lets the model trade a slightly longer route for a much fuller load, or the reverse, depending on which costs less.
Why Should Transportation Be Planned With Replenishment?
In most companies replenishment and fulfillment run first and decide how much to send where and when. Transportation planning receives those quantities as fixed orders and does the best it can. If the replenishment plan releases a few pallets for a store whose route has room for a full truckload, the transport planner can only wait for more volume or send the truck part empty.
When the two are planned together, the replenishment side can round quantities to full layers or pallets, pull forward demand that is due soon, or shift a delivery by a day so it joins a fuller route. The transport side can tell the replenishment plan where spare capacity exists. Warehouse limits belong in the same calculation, since a DC can only load as many trucks as its docks and staff can handle; our post on warehouse capacity planning covers that side.
In Solvoyo’s work with Unilever’s ambient products network, concurrent planning of deliveries and transportation raised load fill by 300 basis points and cut transportation cost by 5%, with carbon emissions down 400 basis points. The details are in the Unilever ambient transportation case study.
How Do You Measure Transportation Plan Quality?
Freight spend alone does not show whether a plan was good, because volume and fuel prices move it too. Better measures normalize for volume and show what the plan controlled:
- Cost per pallet, case or kilogram shipped, by lane and mode.
- Load fill or vehicle utilization against capacity by weight, volume and pallet positions.
- Share of deliveries inside the customer’s time window.
- Share of capacity bought on the spot market versus planned contract capacity.
- Emissions per unit shipped.
- The share of planned loads that dispatchers execute without changing them.
The last measure says the most about plan quality. When dispatchers keep rebuilding loads by hand, the model is missing a rule they know about, and finding that rule usually improves the other measures too.
How Solvoyo Approaches Transportation Planning Optimization
Solvoyo plans fulfillment and transportation at the same time, in one engine. The model matches available inventory to orders using static rules such as channel priority and dynamic rules such as due-date risk, then builds multi-stop, multi-modal and multi-day routes across first, middle and last mile, with truck loading rules, inbound milk runs and fleet or carrier allocation in the same solve. Objectives are configurable through goal programming, and planners compare what-if scenarios before they commit. They can accept, reject or adjust a plan with reason codes, and those codes feed back into the model. Those plans are built to run as issued, and over 95% of Solvoyo’s plans execute untouched.
See transportation and fulfillment planning, or request a demo.
Frequently Asked Questions
Transportation planning optimization uses mathematical models to decide how a company’s freight should move. It covers load building, consolidation, mode and carrier selection, and routing with delivery time windows, and it searches for the plan with the lowest total cost that meets service and capacity constraints.
A vehicle costs almost as much to run part full as full, so cost per unit falls as load fill rises. Load building assigns orders to vehicles within weight, volume, pallet and compatibility limits and in stop sequence, so fewer vehicles carry the same volume. Consolidating orders across customers or days gives the model more orders to fill each load with.
Replenishment decides shipment quantities and timing, and those decisions fix how full trucks can be before transportation planning starts. Planning both in one model lets quantities be rounded to full pallets or layers, pulled forward or shifted by a day to fill a route, which lowers transportation cost without lowering service.
