Delhi Transit Network — Answering "What If a Charger Fails?" Before It Happens

The Problem

Every electrified transit depot eventually asks the question that keeps fleet managers up at night: what happens when a charger breaks, or the grid goes down, on a day the depot can least afford it?

This isn't a hypothetical for a network the scale of Delhi's transit system. A single failed charger doesn't just lose one plug — it can cascade into stranded buses, missed morning pull-outs, and service cuts that show up on the evening news. The operators who plan for this ahead of time are the ones who never have to explain it to a city council after the fact.

How the Depot Digital Twin Was Used

Step 1 — Model the real depot under normal operations. A 50-bus depot was built against its real charging infrastructure — 10 chargers at 240 kW each, feeding a 2,500 kW service — and confirmed feasible under standard worst-day conditions before any failure scenario was introduced.

Step 2 — Run the N-1 charger-loss test. With one click, the Resilience module re-ran the depot's entire worst-day simulation with its highest-power charger removed — not a theoretical estimate, but the same physics engine used for every other result, forced to solve the problem with less equipment.

Step 3 — Read the quantified impact, not a vague warning:

That's not "a charger failure would hurt" — that's "a charger failure costs you 10% of tonight's charging and strands five specific buses," a number a depot manager can actually plan a contingency budget around.

Step 4 — Push further with N-2. Running the same test with two chargers down doubled the impact cleanly and predictably — service loss and stranded-vehicle count scaling with the loss, giving planners a clear picture of how risk compounds as redundancy is stripped away.

Step 5 — Model a full grid outage, not just a charger failure. The Backup Duration test asked a different question: if the grid itself goes down, how long can the depot's own stored energy — batteries plus the surplus energy already sitting in parked buses — keep a critical load running?

Crucially, this number is built on a hard safety rule: a parked bus only ever contributes energy above what it needs for its own next shift. No vehicle is ever stranded to keep the lights on elsewhere in the depot — the tool won't trade one failure for another.

The Result

The Depot Digital Twin gave Delhi's transit planners a precise, quantified answer to both of the resilience questions that matter most: a single charger failure costs 10% of delivered energy and strands 5 buses, and in a full grid outage, the depot's own stored and parked-vehicle energy can carry a 500 kW critical load for 4.5 hours without touching any bus's ability to run its next shift. This kind of quantified contingency planning is exactly the approach validated in published resilience research on real transit networks (Sharma & Nezamuddin, 2026), which demonstrates that adding redundant charging capacity at exactly the right points is a cost-justifiable investment once the risk is properly quantified — turning "what if" into a number a capital budget can plan around.