Could self-driving cars shrink car parks?
New research suggests that the adoption of self-driving cars or autonomous vehicles (AVs) as they are otherwise known, could significantly reduce the amount of valuable space given over to parking in urban areas.
The senior author of a new study in Transportation Research Part B, Professor Matthew Roorda said:
"In a parking lot full of AVs, you don't need to open the doors, so they can park with very little space in between,"
"You also don't need to leave space for each car to drive out, because you can signal the surrounding AVs to move out of the way."
While regular car parks are usually configured for "islands" of cars that can each pull in or out of a spot, an autonomous vehicle car park could resemble a solid grid, with outer cars being able to automatically move aside or out of the way as needed to let cars on the inside of the grid or cars that are blocked in enter and exit with ease.
The researchers' challenge was to determine the optimal size of the grid to maximize storage while minimizing the number of moves required to extract any given car. Mehdi Nourinejad, a recent PhD graduate from the Department of Civil Engineering and the study's lead author said:
"There's a trade-off. If you have a very large grid, it leads to a lot of relocations, which means that it takes longer on average to retrieve your vehicle. On the other hand, if you have a number of smaller grids, it wastes a lot of space."
Nourinejad, Roorda and their co-author Sina Bahrami created a computer model in which they could simulate the effects of various layouts for AV parking lots. They then used an algorithm to optimize the design for various factors, including minimizing the number of relocations and maximizing the proportion of the lot that was used for parking versus lanes for relocation, entering or exiting.
Their results of the computer model analysis revealed that, for a given number of cars, a well-designed AV parking lot could accommodate 62 per cent more cars than a conventional one. Depending on car park dimensions of course.
In some cases they were able to increase the capacity even further. Square-shaped autonomous vehicle car parks of the future could accommodate up to 87 per cent more cars than present configured car parks.
The improved use of space could translate into much smaller parking lot footprints, provided the total number of cars that need to park in them remains constant. Another advantage of AV parking lots is that the design is not fixed. For example, if future demands necessitated it and more car park spaces where needed, you would not need to paint any new car parking spaces. AV car parks would simply not need painted line demarcations to facilitate human drivers. The operator of the vehicle could simply instruct the car to rearrange itself in relation to other AV cars which themselves would be able to communicate and speak with all other cars in the car park grid. In this scenario, it would probably take longer to retrieve your vehicle, but you would fit more cars into the car park.
Roorda hopes that municipal parking authorities in many cities across the world could use this design approach to enhance urban spaces.
"Right now, our downtown cores have giant municipal parking lots next to major attractions,"
"AVs could allow us to both shrink and relocate these parking lots, opening up valuable space in cities."
The concept of an autonomous vehicles self-driving and dropping off a passenger, navigating to an ultra-efficient AV car park and later returning to pick up the passenger sounds very attractive but this new concept could also introduce negative consequences, such as a potential increase in traffic congestion. Roorda went on to say:
"Right now, we have a lot of cars on the road with just one passenger,"
"If we locate AV parking lots too far away from major attractions, we could end up with streets crowded with vehicles that have zero passengers, which would be worse."
Another drawback is that team's designs only work for parking lots reserved exclusively for AVs, rather than a mix of AVs and conventional vehicles, though Roorda says that a single lot could have both AV and non-AV areas.
Roorda and his team also can't predict when the number of AVs on the road will reach the critical mass required to make use of their designs.
"We're talking about large numbers of vehicles that can fully drive themselves, with no requirement for a driver to take over if something goes wrong. There's a lot that has to happen before we get to that stage."