Transit agencies often reach for hydrogen after starting with real operating constraints and skipping a systems-design step. Hills, long duties, heavy passenger loads, constrained depots and the need to keep buses moving are treated as evidence that batteries cannot do the work, so the route is labelled a hydrogen case. Prague’s early operating data suggest a better test: determine what combination of batteries, overhead wire, terminal charging, substations, layover time and annual utilization delivers the service most effectively. That changes the comparison from one vehicle against another to one transit architecture against another. On line 58, Prague’s public transport company DPP compared electric buses and partial trolleybuses with diesel while including vehicle depreciation, infrastructure construction, infrastructure maintenance and related costs. DPP transport director Jan Barchánek said the complete cost per kilometer was about 10% above comparable diesel operation without subsidies and slightly below diesel once grants for vehicles and infrastructure were included. The result is early and route-specific, but that is precisely why it is useful. It shows that a direct-electric system can approach diesel economics on a demanding route when planners fit the infrastructure and operating model to the service instead of assuming that a depot-charged battery bus must reproduce diesel operation unchanged. The evidence is more revealing because it comes from line 58 rather than only from Prague’s higher-profile airport route, Line 59. It combines steep grades, high passenger volumes, frequent service and large double-articulated vehicles, making it an obvious candidate for in-motion charging. Line 58 makes the strategy look less like a showcase and more like network planning. Modern in-motion charging trolleybuses are battery-electric buses that draw power and recharge under selected sections of wire, then operate from their batteries where wiring is visually intrusive, operationally awkward or uneconomic. The approach occupies the middle ground between depot-only battery buses and continuous-wire trolleybuses. The most important technical number is the share of the vehicle’s energy that must pass through the battery. DPP says only about 40% of a partial trolleybus’s energy flows through its battery, while effectively all traction energy passes through the battery in a battery-only bus. That difference affects battery size, cycling, thermal management, replacement and charging windows. A battery is not a one-time line item in a procurement spreadsheet. It is an operating component that is repeatedly charged, discharged, heated and cooled, often sized for the hardest day rather than the normal one. Selective wire supplies direct power on the steep or heavily loaded sections and recharges the bus during passenger service, leaving the battery to provide flexibility where stored energy adds value. Prague’s conventional battery buses point in the same direction. DPP says its older Škoda electric buses with Temsa bodies operate at about 104% to 105% of diesel costs before subsidies on suitable services and slightly below diesel after subsidies. They benefit from Prague’s existing electric-transit ecosystem, including substations, tram infrastructure, regenerative braking energy and terminal charging. Utilization then changes the capital arithmetic. Prague’s diesel buses average about 50,000 km per year, while its electric buses reached 67,000 km, close to the 65,000 to 70,000 km range where Barchánek said the economics begin to work. A bus that charges during passenger service may spend less time idle, spread its capital cost across more useful work and reduce the need for oversized batteries, chargers, depot space and spare vehicles. This is where many hydrogen comparisons become incomplete. The usual case starts with a difficult route and compares hydrogen with a battery bus expected to carry every kilowatt-hour, absorb every peak load and recharge only when it stops. Prague shows that difficult routes can be divided among depot charging, terminal charging and selective wire. Hydrogen must then compete with those actual alternatives, including their utilization, battery requirements and infrastructure life. A hydrogen bus also brings production, compression or liquefaction, storage, transport or on-site generation, dispensing equipment, safety systems, specialized maintenance and exposure to delivered fuel prices. A direct-electric system requires wires, chargers, substations, batteries and grid connections, but it avoids adding a fuel-conversion and distribution chain between electricity and the wheels. Subsidies require the same discipline. Prague’s line 58 result falls slightly below diesel after grants, but grants do not remove costs; they allocate them. Funding for wires, substations, chargers and electric buses can establish public infrastructure that serves multiple routes and successive vehicle generations. Funding for hydrogen buses often supports participation in a specialized fuel system that must still demonstrate acceptable delivered fuel costs, station reliability, vehicle availability and repeat procurement once pilot support fades. The relevant question is not whether either pathway receives public money, but what durable operating capability the spending leaves behind. Prague’s lesson is not that trolleybuses should replace battery buses across an entire network. Depot-charged buses suit routes where ranges, schedules and charging windows fit. Opportunity charging suits services with useful terminal layovers and available electrical connections. In-motion charging fits corridors where hills, passenger loads and high utilization make battery-only operation unnecessarily burdensome. Transit agencies should classify routes among those options before introducing a second energy supply chain. Procurement should require route-level modelling of annual kilometers, passenger loads, gradients, layovers, battery replacement, charger availability and selective-wire alternatives rather than allowing a preferred drivetrain to define the problem. Many routes described as too difficult for batteries are really routes where the battery should work with the electrical system around it. Prague is now putting early cost and utilization evidence behind that distinction. Read the full analysis in TFIE Strategy Briefing: Prague’s Trolleybus Data Clarify The Hydrogen Bus Problem Subscribe for evidence-led analysis of transit procurement, direct electrification and the infrastructure decisions hidden behind technology-neutral language.