A Formula E team’s race strategy begins life long before they even arrive at a racetrack, with data-based simulations predicting everything from mechanical set-up and the perfect racing line, to the amount of energy used on each lap and the optimal points around the circuit to harvest or regenerate energy under braking. So in an ideal world, a top team can turn up and, with only minimal adjustments, know exactly how its race should unfold and on which lap it’ll need to make a pitstop for the scheduled car swap… only we don’t live in an ideal world.
In Mexico City, not even the most advanced simulation software or cleverest of engineers could’ve predicted the way the race would turn out, and at times like that, the best teams are those that can think on their feet and react to the constantly changing circumstances. At the 2017 Mexico City ePrix, some teams were tested more than others, but there can be little doubt about who came out of the whole thing with the biggest, and most deserved smiles at the end.
When we talk about formulating a race strategy in Formula E, there are lots of factors that go into it. Initially relying on data collected, either from previous visits to the circuit, or more often than not with the way the series moves around to more and more new venues, from detailed drawings and plans of the city centre track layout. Some teams rely on maps issued by Formula E, once a track’s homologated, and combine that with data from web-based sources like Google Earth to build as accurate a picture as they can of exactly what the venue will look like. Others subcontract specialist companies with sophisticated equipment to measure and scan the real-life track as soon as it’s completed and feed the detailed information into their simulation tools to improve accuracy. Exact corner radii, lumps and bumps in the road and even the abrasiveness of the Tarmac can be forensically measured and help to give those teams a better understanding of what to expect before they arrive.
The data, however it’s collected, is used to simulate the demands of the particular circuit on that team’s car and drivers. Software can calculate energy demands for each lap and predict, with regen, on which lap they need to pit, just as the battery’s useable energy reaches 0 per cent. Grip levels of the asphalt, cambers of the roads, locations of manhole covers and painted white lines that become hazards when wet, all help to generate plans in the minds of engineers and drivers, who of course see major benefit from being able to drive the most representative simulation of a circuit that simply doesn’t exist before Formula E turns up in town.
So everyone arrives with plans, but until they get out there, firstly for a track walk and then the Friday afternoon shakedown, they just don’t know whether what the computer says, matches up perfectly with the real world. Even then, we all know what they say about the best laid plans.
By the time qualifying’s done and a team knows where it and its rivals are starting the race from, various race strategies are finalised. Typically a team might have a Plan A, B and C mapped out, that can be activated depending on their position after the start and first lap, or if the Qualcomm Safety Car features for example. But sometimes it just boils down to a team being brave, thinking on its feet and trying something the simulations would never have predicted, and when Lucas di Grassi found himself starting 15th, and was subsequently involved in a first-lap crash, which broke his rear wing, that’s exactly what happened.
Lucas himself said he thought any faint hopes of rescuing a result from his disastrous qualifying had disappeared when he felt the clatter from behind and saw the rear wing hanging off in his mirrors, yet somehow he ended up winning the race. From the garage, the team was perhaps thinking the same when it called him in for the inevitable visit to the pits. But even at that stage it had a decision to make. Given the predicament, abandoning the race and changing cars to go for an all-out assault on the Visa Fastest Lap point would’ve been understandable, but it chose to replace the wing and send the car back into the ePrix.
At that point the Qualcomm Safety Car was deployed as on-track debris was cleared and it opened up a very slim opportunity to bring Lucas back into play. He would rejoin last, but could effectively start his race again, negating the time taken spent in the pits as the field was led round the track slowly, even if he was a few places further back. Anything can happen in Formula E, so that early in the race the team can still see point scoring as an outside possibility, so the plan was to continue and pick up places wherever possible.
Minor adjustments would’ve been made to Lucas’ energy targets, calculated by the team’s strategy software and he continued with only a slim possibility of capitalising on the potential misfortune of others.
When the cruelest of misfortunes struck Oliver Turvey and his race-leading NextEV car ground to a halt in a dangerous position, the strategic options opened up further for Abt Schaeffler Audi Sport. The Qualcomm Safety Car once again slowed the field to a safe pace and at that moment the team was furiously calculating from the garage, the outcomes of various decisions it could take.
It could use the safety car period to save more energy and release Lucas to attack the bunched up pack in front of him as the track eventually went green again. That was a viable option as with cars already having dropped out of the race and more likely to before the chequered flag, the chance of making it into the top 10 point-scoring positions was reasonable given the pace of its package. In fact, from a similar position on track and with an arguably less competitive car, Nelson Piquet Jr and the NextEV NIO team chose to do exactly that and picked up two points for P9.
The alternate, and far more high risk, strategy was to roll the dice and take a huge gamble. Two or three points would’ve been seen as a disappointment for the Abt team, particularly with chief rival, Sebastien Buemi looking likely at that stage to score highly, so the frantic conversations in the garage intensified.
At that moment, the team have the time until the car reaches the pit entry to make and communicate a decision to the driver. Engineers input variables into the strategy software, which then calculates the possible outcomes and feasibility, so when the option of pitting for the car swap, a full seven laps earlier than the scheduled stop lap, was keyed into the system, it was an unlikely scenario. No car had ever done a 28-lap stint in a Formula E race, it was unprecedented. The chances of making it to the end were slim and even if it could, the pace would have to be so slow to stretch the available energy, Lucas would’ve been a sitting duck.
The flip side of that decision, and not something the energy strategy software simulates at the track, is that by pitting under the safety car, he’d end up at the back of the closed up train, but with no need to stop again. With such a bunched field, he could stay in touch once the Qualcomm Safety Car eventually pulled in and move to the front as everyone else inevitably pitted in the predicted pitstop window just a few laps later. The software would’ve told the engineers their car would be down to around 60 per cent of usable energy left, with the rest of the cars on fresh batteries, but track position counts for a lot on most Formula E tracks. This is where experience, calm heads and a team environment that encourages bravery and calculated risk taking, combined with accurate data, can really make the difference.
The team has to weigh up the risk of plummeting down the field and out of the points as energy reserves become too low to fight off competition (Jerome D’Ambrosio) at the end, against the reward of possible further energy saving safety car periods and a generally high attrition rate.
Race engineers, team management and Lucas himself will have all been involved in the high-pressure decision making process over the course of that lap back towards the pit entry and in the end somebody had to make the call. In he came.
Of course a gamble like that also relies on a certain amount of unpredictable luck to fall your way too and they certainly got that. A team might argue the luck was factored into the calculations. Probability of accidents resulting in safety cars at that track, experience of its driver, energy characteristics of its car, being first to make the call so if anyone else replicated the strategy they’d provide a buffer behind di Grassi (D’Ambrosio) and the number and location of overtaking opportunities around the Autodromo Hermanos Rodriguez track. All these things would’ve been part of the discussion that led to one of the most exciting races in Formula E history and one of the most inspired and brave calls by a team resulting in an unforgettable victory.
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Marc Priestley
@f1elvis