Mixed-Fleet Routing: EVs in the Zone, Diesels on the Ring
The Logic of Splitting a Fleet by Powertrain
Mixed-fleet routing starts with a simple premise: not every vehicle needs to enter the city center, and not every vehicle is allowed to. Dutch low-emission zones increasingly restrict older diesel vans and trucks from inner-city streets, while electric vehicles retain full access regardless of zone boundaries. For fleet planners, this creates a natural division of labor. EVs become the default choice for last-mile drops inside the milieuzone, while diesel vehicles are rerouted to handle outer-ring deliveries, warehouse-to-hub transfers, or consolidation runs that never cross the restricted perimeter.
The challenge isn't deciding who goes where in theory — it's building a routing model that executes this split automatically, every day, without manual dispatcher intervention eating into planning time. A static rule like "diesel vans stay outside the ring" only works if the planning software actually knows where the ring is, how it's enforced, and how it changes between cities.
Keeping Same-Day SLAs Intact
The real risk in mixed-fleet routing isn't compliance — it's the hidden time cost of rerouting. When a diesel van can't take the shortest path into a city center, the detour around the ring road adds minutes that compound across dozens of stops. If EVs are scarce in the fleet or concentrated at one depot, they can become a bottleneck for same-day delivery windows, especially during peak demand.
The fix is treating zone restrictions as a routing constraint from the start of the planning cycle, not as a correction applied after routes are built. Depots closest to a milieuzone should be stocked primarily with electric or zero-emission vehicles, with diesel units positioned at depots that naturally serve ring-road and suburban clusters. This reduces the number of cross-zone handoffs needed per day and keeps drive times predictable.
Transfer points — small hubs or parking locations just outside the zone boundary — also help. Diesel vehicles can drop loads for EV couriers to complete