UK HGV platooning trial

A very long time ago (October 2017) I wrote that the UK government had given the go-ahead for trials of vehicle platooning on UK roads. I wrote that these were "expected to happen later in 2018". Ah, I was younger and naïve then.

In reality the consortium led by TRL that won a £8.1m UK government contract to run the trial spent 2018 in the planning phase of the project. The second phase of the project is scheduled to begin in the spring of 2019 and last for four months. This will shake down the vehicles and technology, before the third phase of the project involving DHL drivers and DAF trucks, and lasting eight months. 280 journeys of around 100 miles each will be data logged, half of which will be HGVs in normal operation, and the other half will be three HGVs platooning. The final phase of the project, presumably running into 2020, will be the analysis and reporting to make an economic case for HGV platooning.

Surprisingly neither the UK government, via Highways England which is overseeing the project, nor TRL list the project on their websites. The report from the 2014 case study, also led by TRL, is available here. But to get an update on the HGV platooning trial you have to delve into the commercial haulage press to read about TRL's chief executive, Rob Wallis, delivering a project status update to a Transport Conference back in May 2018. The bits that I'm interested in, such as which V2V technologies they'll be using, are still a mystery. As a publicly funded project, I'd like to think it would be a bit more transparent than this.

What is available is the 2018 report on the public dialogue carried out by Kantar on behalf of the Department for Transport, which included the public's reaction to HGV platooning (on pages 35 and 36). Bizarrely there are statements in this report that imply that only the lead HGV in the platoon would have a driver in the cab. This is reinforced by the report's feedback on business reaction (on pages 66 and 67) where there is talk of "platoon hubs" at motorway junctions where drivers wait to take vehicles out of the platoon and onto local roads. If this is how platooning was portrayed, then no wonder the reaction was predominantly negative.

Autonomous cars & speed limits

The progression of electric vehicles is being mirrored by the progression of autonomous vehicles, with most mainstream manufacturers now offering varying levels of driver assistance and autonomy. SAE Level 2 autonomy enables "hands off" driving, where the vehicle maintains speed, braking and steering, whilst the driver remains "in control" and ready to take over should the vehicle not choose the correct course of action. Essentially any vehicle with adaptive cruise control and lane departure warning technology is knocking on the door of Level 2 autonomy.

This year the UK government gave the go-ahead for the first trials of platooning vehicles, which is expected to happen later in 2018. The significance of this trial is not in the technology; this has been proven in the lab and on closed tracks and there is no way that the public highway would or should be used to find out if technology works. The significance is to characterise the known unknowns, especially how other drivers and vehicles on the road interact with the platooning vehicles, and the emergent behaviours this will create.

There appear to be two main objections to platooning vehicles on UK motorways; firstly that they'll obstruct slip roads, and secondly that they'll obscure signage. On a personal level I disagree with both of these points. Slips roads are signposted a mile in advance, giving vehicles plenty of time to filter into the left hand lane, and bigger vehicles can already obscure signage from smaller vehicles, so this is not an issue caused by platooning vehicles.

However the huge significance of this trial for me is that permission has been given for platooning vehicles to break rule 260 of the Highway Code, i.e. "...keep a safe distance from the vehicle in front". In this trial the platooning vehicles will not be a safe distance from each other, if they were being driven manually. And this is an important point, as platooning vehicles are operating at Level 3 autonomy, where the driver is not able to take control should the vehicle not choose the correct course of action. At Level 2 autonomy the vehicle is always being operated safely, as the driver is ready to take over if the autonomous systems are not operating the vehicle safely.

So this trial is setting a precedent whereby a Level 3 autonomous vehicle need not meet all the rules of the Highway Code. Rules 124 and 125 immediately spring to mind, as they deal with speed limits. The key to this debate is the unbalanced nature of these rules, especially as captured in rule 125: "The speed limit is the absolute maximum and does not mean it is safe to drive at that speed irrespective of conditions." I don't think many people would argue that in the depths of a snowy winter driving exactly at the 30mph limit down a street crowded with festive shoppers may not be not safe. But I also don't think many people would argue that exceeding the speed limit by a few mph on a dry, deserted motorway is any less safe than at the speed limit.

So the debate that is looming is this: if a Level 3 autonomous vehicle can determine when it is safe to platoon, surely a Level 3 autonomous vehicle can also determine when it is safe to exceed the current speed limits, and by how much. And this will be a debate based on opinions and feelings rather than cold hard facts. There is hard data to prove that autonomous systems can safely drive a car well in excess of the speed limit, but many drivers are still wary of much simpler driver aids. For example I know many experienced drivers who shun manual cruise control. These are the people that need to be won over.

Hopefully they will be won over, because higher levels of vehicle autonomy are key to free-ing up the UK's motorway network. Instead of smart motorways with variable speed limits and roadworks to add lanes to already congested roads, we could have more cars, travelling faster, closer together, and all safer than we are at the moment. What's not to like about that?