I work at a private service ambulance company. We currently have 9 stations with wheelchair vans, medic trucks, and up to 9 BLS trucks per station.
We’re looking to add a tenth station and a tenth truck, with long-term plans to add more of each. The problem is that our current numbering system will not accomodate these changes.
Our current system:
Wheelchair trucks start with a 1 and are numbered sequentially: 101, 102, 103, etc.
BLS trucks whose headquarters are at, for example, station 2, start with a 2 followed by two digits: 228, 225, 210, etc.
Medic trucks whos headquarters are at, for example, station 9, start with an M, a 9, and then one digit: M91, etc.
Thrown into the mix is an altogether different numbering system of our vehicles themselves, which are assigned by the state in four-digit fashion with apparently random digits, that we have no control over. Thus, we would like to stay away from four-digit numbering for our trucks.
While future-proofing may be impossible, we’d like to future-resist as much as we can. We’ve thrown a few ideas around, but none have really struck our fancy.
If I’m reading this correctly, you want your numbering system to encompass the following information:
Headquarter (1-10+)
Vehicle type (Wheelchar, BLS, medic truck)
State-assigned registration number: (1234)
Vehicle number (relevant to HQ stall)
How about:
W-X04-1234
Where type is addressed as a letter - W, M and B - and HQ/number is a roman numeral with number after and then the license number is also put into a number.
Examples:
B-VIII02-2134
BLS 02 from HQ8 State license 2134.
W-V05-2144
Wheelchar 05 from HQ5 State license 2144.
Or how about taking station names from the phonetic alphabet? Alpha, bravo, charlie, etc. And putting the roman numerals as truck numbers.
W-AlphaIX-2144.
Wheelchair 9 from HQ Alpha, state license 2144.
I should have been a little more precise in one sentence, and added another. The state-assigned number does not need to be part of the truck number, I only threw that in to eliminate outright the possibility of a numbering system involving four-digit numbers. Additionally, these are identifiers that will be spoken on the radios ad nauseum and written on paper, whiteboard, and computer repeatedly. They should be as succinct as possible. This, I believe, throws out the possibility of Roman numerals. But I like where you’re going.
I also like where you’re going. I mentioned myself using a hex system, but letters without numbers might work better.
So if I understand correctly you want to communicate three pieces of information:
[ul]
[li]The station of origin of the truck[/li][li]The type of truck[/li][li]An identifying number for the truck[/li][/ul]
Assuming that you don’t have more than 9 of any TYPE of truck at a particular station, how about:
The first digit is the number of the station. For the tenth station and beyond you start using letters instead of numbers. 1-9, then A, B, C, D, etc.
The second digit is a letter that indicates the type of truck. Like what you’re doing now with the medic trucks.
The third digit is the truck’s identifying number.
So, for example, if you had two medic trucks at your new tenth station, they’d be called:
**
AM1 & AM2**
If you had three BLS trucks at station number 4, they’d be called:
4B1, 4B2, 4B3 & 4B4
And if for some reason you eventually had to have more than nine of one type of vehicle at a station, you can extend using letters as well. So the eleventh wheelchair truck at station 1 would be called:
1XB
(I recommend using X instead of W or C for wheelchair since W is difficult to say quickly over the radio and C could be confused for B.)
Assume you denote stations as positive numbers from 1-10, trucks by positive numbers from 1-3, etc. (i.e. ambulances are represented by a 2).
enc(StationNumber, TypeOfTruck, TruckID) = 2^StationNumber x 3^TypeOfTruck x 5^TruckID
For example, the fourth ambulance from station 5 is enc(5, 2, 4) = 32 + 9 + 625 = 666
There’s now no limits on the number of station, types of trucks or number of trucks of each type that you have. If you want to add more information, just add another prime and raise it to the field.
Of course, due to the Fundamental Theorem of Arithmetic, you can recover the type, location and number of a truck purely from the assigned codenumber.
Unless you really have a need to communicate information in the identifier, the best procedure is generally x digits sequential or random.
Based on experience with putting logic in identifiers, if you do put logic in it, it’s almost guaranteed that future changes will screw it up. When you merge, get bought out, greatly expand, etc. (which always happens, even when you think you are safe from these types of changes), then the logic won’t work anymore. But, sometimes it still makes sense just to put the logic in and deal with the changes later.
My non-expert though is to start right away with ‘A’ for station one, rather than waiting until the tenth station, because it could be confusing for some trucks to have the first digit being a number and some a letter.
Of course, going with single letters for the station will fail once you grow by another 2 1/2 times…
Not if you keep the code Letter-Number-Letter (or Number-Letter-Number…). A-1-A can become AA-1-A for that 27th station. Or A-1-A can become A-1-AAA for that 677th wheelchair truck.
Not bad, but if you change it to number-letter-number, you eliminate any confusion over the digits.
Lots of letters sound alike, so you could use the phonetic alphabet (“eight-whiskey-four”, “ten-bravo-seven”), or just use “wheelchair”, “medic”, and whatever the ‘B’ in BLS stands for.
Has anyone asked the drivers what they want? They’ll be the ones listening to the radio and have to recognize their call sign. What will get their attention faster, a station number or type of truck?