1. Parking Tour Generator September 2018

2. Parking Tour Generator
Explores a sequence of roads like a parking expert would
Guidance tells you when to park, or not park
Parking Tour in vicinity of destination is constrained by max preferred walking time
Link 1 is the first within max walking time (here it is 10 mins)
Red means “don’t park yet”
Black means “park if there is a space”.
Map tiles and road data © OpenStreetMap contributors

3. Parking Tour Generator
Tours differ from Routes in important ways
There is no specific end point.
The Tour does not know where available parking spaces are, it just knows parking probabilities.
The same road may be visited multiple times if that is an easy way to explore the area. (No loops in Routes).
A series of roads may be visited multiple times if enough time has elapsed for spaces to be vacated.
The tour may recommend NOT parking in some places if it knows better opportunities are coming.
There may also be areas bad for parking where the final walk is difficult, or parking time or cost restrictions apply.

4. Parking Tour Generator
Cost Function
The Parking Tour Generator is very different from a Router
There is still a Cost Function though to model the trade-offs a driver makes
Weighting includes:
Driving Time
Walking Time
Parking Charge
Parking Time Restictions
Ease of Driving, e.g. left or right turns
Ease of Walking, e.g. major road crossings

5. Parking Tour Generator
Probabilistic Cost Function
We do not know where parking spaces are available, only the probabilities of finding a space
To find a Tour we do not minimise components such as Walking Distance, but rather Expected Walking Distance
This approach is very flexible, e.g.:
Less walking if it is raining, with a longer tour
Faster parking if late, perhaps in a more expensive space
If there is plenty of parking our Tour will head straight for destination area.
When parking is rare the Tour will cover roads further from the destination, but in a pattern the covers the maximum area in the shortest time.

6. Parking Tour Generator
Data Requirements
Historical Parking Data
The probabilility of parking on a given stretch of road at different times of the day and week
Churn Interval
How soon it might be worth re-visiting a stretch of road
The algorithm gives useful results if only partial data or no data is know
A default Churn Interval of a few minutes works well
A default parking probability on appropriate roads generates useful Tours

7. Parking Tour Generator
Example Tours
Plentiful Parking
A good Tour will search near the destination.
The Tour will advise against parking until the destination is within easy walking distance.
Here, a uniform parking probability of 0.1/100m advises parking from link 12 onwards.
Map tiles and road data © OpenStreetMap contributors

8. Parking Tour Generator
Example Tours
Parking is rare
Advice to park at an earlier stage.
This will reduce the expected Tour time.
A uniform parking probability of 0.03/100m advises parking from link 6 onwards.
Map tiles and road data © OpenStreetMap contributors

9. Parking Tour Generator
Example Tours
High
Churn Rate
It is worth revisiting a road if enough time has elapsed for the parking probability to have recovered.
Here, the Tour driving time has been increased to 600s, and more loops are generated.
Map tiles and road data © OpenStreetMap contributors

10. Parking Tour Generator
Example Tours
Low
Churn Rate
It is now best to drive a larger circuit before revisiting roads.
Here, links [17,44] and links [12,46] are revisited after 5 mins.
Map tiles and road data © OpenStreetMap contributors

11. Parking Tour Generator
Example Tours
Dislike Walking
We expect to see more time driving, but closer to the destination.
Map tiles and road data © OpenStreetMap contributors

12. Parking Tour Generator
Example Tours
Emergent Behaviour
The tour explores all the aisles sensibly, exploring the end ones first as they are closest to the walking paths (except for [57, 58] as that is one-way)
Map tiles and road data © OpenStreetMap contributors

13. Parking Tour Generator
Example Tours
Turn Penalties
The surprising behaviour when we applied an artificially high weighting was a tour that visited all the aisles while never turning right after link 24 (in the UK)
Map tiles and road data © OpenStreetMap contributors

14. Parking Tour Generator
Example Tours
Extreme Tours
How to optimally find a space in a Park and Ride
Map tiles and road data © OpenStreetMap contributors