DHL has just updated its Trend Radar[1] report in which it forecasts the impact of new logistics technologies. The 2016 report is more positive than the last one in 2014 about the delivery of parcels by Unmanned Aerial Vehicles (UAVs), or drones as they are now more popularly known. It, nevertheless, concludes that they ‘still require a bit more time before mainstream adoption’. Their likely impact on logistics over the next 5 years is rated ‘medium’. DHL acknowledges that ‘while UAVs won’t replace traditional ground-based transportation, they will provide value in areas of high traffic congestion and in remote locations.’ I can see how drones will allow parcels to hover above congested roads and get to their destinations more quickly, reliably and directly. I’m not so convinced by DHL’s claim that ‘by potentially reducing the amount of vehicle movements, UAVs can provide traffic congestion relief to densely populated cities’.
Some simple arithmetic suggests that to achieve a noticeable reduction in urban traffic levels, the sky above our towns and cities would have to fill with drones. Let’s compare conventional home delivery by van with distribution by drone. A typical van delivering non-food items to homes in the UK can deliver around 120 parcels in an 8 hour shift. A drone, on the other hand, delivers one parcel at a time. It is not known how many deliveries a drone would be able to make per hour. This will depend on the density of delivery locations, the size of catchment area served by the drone despatch depot and the speed of the handling operations at both ends of the flight. One delivery per hour would seem a reasonable estimate. This suggests that it would require 15 drones to replace a single van.
Imagine that we wanted to substitute drones for vans in sufficient numbers to reduce urban traffic levels by 1%. According to the government’s Road Traffic Statistics[2], in 2014 there were 163.4 billion vehicle-kms of traffic on urban roads in the UK. We would aim to reduce this by 1.634 bn vehicle-kms per annum by removing many of the vans from the urban road network. It is difficult to calculate exactly how many vans this would be because of data limitations, but one can make some crude estimates. The average van travelled 13,700 kms in 2014. Assuming that this average applies to vans making parcel deliveries in urban areas, we would have to replace 119,270 vans with drones to cut traffic volumes by 1%. With a drone : van substitution ratio of 15:1, we would have to deploy around 1.8 million drones over our towns and cities – to achieve only a marginal reduction in surface traffic levels and congestion. Even if the vans being replaced are used twice as intensively as the UK average (travelling 27,400 kms per annum) and the substitution ratio is only 10:1, we would still need 600,000 drones.
Most urban dwellers and city planners would baulk at the environmental and safety implications of having their air-space invaded by such large swarms of drones, particularly if the resulting ‘congestion relief’ on the ground was barely perceptible.
[1] Click for link to DHL Trend Research paper
[2] Click for link to UK government statistical research page
A welcome blast of common sense! Thank you for these useful calculations, which put the whole notion of delivery by drones into perspective.
I suspect that an equal concern over the idea must be the safety aspect. We know the aviation industry is already worried about the risks of air strikes by poorly controlled drones – and that’s when there are just a handful of them in use, not millions. If even one of these millions failed over a crowded environment, a railway track or a major road, the potential for injury and damage defies imagining.