Quote:
Originally Posted by aberdeen5698
I'm guessing that you're thinking something like this: 20% of commuting trips are done by transit so all we have to do is to increase road capacity by 20% through automation to break even. But you're making two mistakes here:
First of all, transit + vehicle trips don't add up to 100% because about 20% of the total are walking and cycling trips. So the share of transit trips that use road lanes is more like 25%.
The second, much more blatant error, is in assuming that road capacity is proportioned by the number of people.
If you move people out of buses and into autonomous cars, the amount of road space that they consume is going to explode by several hundred percent. There's no way to make that work, period.
Buses are still going to be with us in an autonomous world, and they'll be autonomous too.
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That picture is flat out misleading. The passenger load will be spread out evenly across the city.
Let's isolate a driverless car service scenario down to one route, say the 3 Main, which is one of the busiest routes in Metro Vancouver. The driverless cars will only operate along the same route that the 3 Main covers.
During rush hour there are 9 buses operating north bound during the afternoon rush. The peak load for 1 bus during the afternoon rush is 111 boardings per hour, so we calculate how many driverless vehicles it would take to shuttle 111 people in 1 hour. I'm going with 11. That means 10 passengers per hour for 1 driverless car. That's easily doable because there is high turn-over along this route. People getting on dt, then getting off at Skytrain. People getting on at Skytrain will be getting off at Broadway etc.
Then we multiply the number of driverless vehicles by 9 to match the capacity of the buses on this route. That comes to 99 driveless vehicles, vs the 9 buses.
So now we have to fit 99 vehicles over 10 km, but to be fair when we are talking about road space we have to take into consideration how much road space is gained when we take those 9 buses off the road.
An articulated bus (which are run on Main St) is 60 feet long. A sub compact car is 10 feet long, so in the space of 1 articulated bus you can fit 2 driverless vehicles. That leaves a 40 foot distance between the 2 cars. That's plenty during rush hour. The space that buses take on the road is equivalent to 18 driverless vehicles (2 x 9 buses). That leaves 88 cars we have make room for over a 10 km stretch. That averages out to 1 car every 113 meters, or about 1 car every block. There's going to be more demand in the busier areas around the Skytrain station and the B-Line stop, but where buses once dominated the curb lane in the more congested areas, driverless cars could now take advantage of. Once buses are gone, there will be increased capacity in the curb lane.
The bus routes outside of the core of the city are less busy, and once you get out to Surrey there are routes that are far less busy. than the inner city routes. Once the less busy routes are running almost empty most of the day, Translink is going to have to shut them down, and then make some serious decisions on how they run transit city wide.
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