Mini-Class Theoretical Hourly Ride Capacity (THRC)
As the creative idea for a new ride attraction are being formed there is a Theoretical Hourly Ride Capacity (THRC) number assigned as a target to meet. Many ride ideas have been scrapped over the years because there was a wonderful creative idea but the practical implementation of that idea would not allow very many guests to experience it.
THRC is simply calculated by how often a ride vehicle is dispatched into the ride times the number of seats in the vehicle. The word theoretical is there because it assumes that every seat is taken and that there are no delays in loading which there can often be. There is OHRC term for Operational Hourly Ride Capacity which is what is really possible in the real world.
Though these numbers are secret, anyone with a stopwatch can figure them out. As you load on Space Mountain at Disneyland, for example, your stopwatch will show that about every 20 seconds a rocket leaves with 12 guests on it. Now we calculate 3600 seconds per hour / 20 second dispatch * 12 guests or 2,160 guest-per-hour. It doesn't matter how many vehicles are on the track except there must be enough that you never wait for a vehicle to return from the ride. So you can see there is an optimum number of vehicles. Too few and you "starve dispatch" too many any there is nowhere to put them.
When I started at Disney in 1979, E-Ticket attractions wanted around 2,400 THRC. Over the years that number would lower some to allow for some wonderful attractions to be built. Now walk over to the Pirates of the Caribbean ride with your stopwatch and count the possible number of guests in that big boat. Your math will show you thousands of more guests per hours are possible.
The first Space Mountain (in Florida) had two separate ride tracks in one building with 8 guests per rocket, when Space Mountain Disneyland was built the same capacity was achieved with 12 guests per rocket and a faster dispatch interval.
It gets more complicated on rides that are hard to fill each seat. The original Space Mountain (Florida) and the Matterhorn in the 1980's had seats were the second guest sat in your lap. I loved these rides because I was able to have my young son ride with me without fear but as you can see people that don't know each other aren't going to sit in a stranger's lap (except for grad nights). So, it turned out that the average guests dispatched was about 75% of the theoretical. Notice that years later the seats in both rides were changed to 6 individual seats rather than the original 8 seats (4 two guest seats). I understand the change but a little sad about the loss of a fun sitting arrangement.
Simple THRC Calculator
Back to Mini-Classes