“…., but I really would like to hear from an operator that has an RFID or similar system. Someone to corroborate the opinions here will go a long way in helping me understand why this might be a less than desirable option.”
I can assure you my opinion comes from being a former carwash operator.
I can also use statistics to demonstrate.
The service rate of an in-bay is the total time it takes to complete one wash.
The stop watch starts when a customer stops at the pay station and stops when the customer exits the wash bay.
Let’s assume the service rate is 12 cars an hour or an average of 5 minutes a wash.
The nature of a single server line is that the length of the waiting line and average waiting time will grow rapidly as the arrival rate of customers (random) approaches the service rate of the machine.
So, if your machine has service rate of 12 cars an hour and the arrival rate of customers is 9 an hour (an average of 60 cars daily), you will have 4 or more vehicles in the system 32% of the time.
The problem is when the arrival rate of customers exceeds 9 an hour, the length of the waiting line and average waiting time will grow indefinitely. Who wants to wait in line for 20 or 25 minutes to get a carwash?
As the other gentleman mentioned, people will pull out of line with as few as two cars in line.
Again, if you have long lines, you are not washing all you can get. Once people pull away, you can’t make up for today’s lost business tomorrow.
This is why slow in-bays are more suitable for lower volume applications.
RFID may give you capacity to support unlimited and a bit more speed, in an in-bay environment, but remember it will only have an effect on the portion of time it takes to complete the sales
transaction part of the total wash process/service time.