How much is too much?A couple days back, I took an hour or so out of my afternoon to track down the genetics of one of Seattle’s more established Indian restaurants–Pabla India Cuisine, which has been operating out of a single location at 2nd and Pike for the past 17 years. The reason Pabla had caught my eye is that, after all those years of serving Indian food to the downtown masses out of just one address, it has suddenly up and expanded, adding not just one additional location, but two. And the reason it took me an hour to get things straight is because there are at least two other restaurants in the area which have some version of the name “Pabla Cuisine” but are completely unrelated to the original Pabla or either of the two new Pablas.So fine. That was done. But after I put up the post about Pabla, it’s new SeaTac location (at 15245 International Boulevard) and it’s so-new-its-not-even-open-yet location at 2nd and Madison, commenter cr45seattle asked what I guess should have been a fairly obvious question: why?”Wait…” he wrote. “I’m confused. Why do we need two indian restaurants in downtown within 5 blocks of each other run by the same people?”The answer, cr45, is both a mathematical and an anthropological one, easily summed up by two words: carrying capacity. On the surface, it might seem ridiculous that one family might choose to open two restaurants of the same style, with virtually identical names, so close together. Common sense says that the original, successful restaurant will suffer as the second cannibalizes the customer base and pulls trade away from the established address. Throw a third address into the mix (even one that’s relatively far away from the original) and this just complicates things further.My counter-argument to this? Starbucks. In downtown, there are stretches where you’ll get three within six blocks, five within a two block square. That’s a lot of mocha lattes, brother. And when you add in other coffee shops (Tully’s, Seattle’s Best, independents and the like), you’re looking at a saturation that far exceeds two Indian restaurants in five blocks.The reason this works is carrying capacity–a term that essentially means the maximum population size of any species (human, water buffalo, Indian restaurant or what-have-you) that can be sustained by the environment, given the amount of food, water and other necessities available in that environment. To continue the coffee analogy, in Seattle, lots of people need coffee. Lots of people need coffee several times a day. And since coffee has become a necessity to them, it becomes important that this coffee be both available and easily accessible. A one-block walk for that morning Americano? That’s reasonable. Even two is okay. But at three, the “cost” (in effort and time, not necessarily in dollars) starts to ramp up psychologically until the potential coffee-starved customer decides that maybe just staying at his desk and suckling at his giant Nalgene water bottle is enough.And that, to Starbucks, is a lost customer. At $3 a day, 5 days a week, 50 weeks a year that means that they have lost $750 in potential earnings. And it doesn’t take many walking, talking $750-a-year profit monkeys to make it worth the company opening yet another location just so that Suzie Lazypants can get her daily fix without having to haul her ass up too many hills.Back to the Indian restaurant and its smaller-scale equation. The folks at Pabla have determined that there are enough potential customers with a taste for curry packed into the downtown area that offering them a second location for an Indian lunch buffet will, eventually, become profitable. Think for a minute how far you would be willing to walk for an Indian lunch buffet. I’m guessing you’re going to top out around three blocks, same as our coffee fiend above. This means that, for 17 years, the original Pabla has been drawing a good chunk of their lunch trade (not including those who have driven there, either for lunch or dinner) from people who live or work within a couple blocks–say from Western to 4th, between University and Stewart. Considering the density of that area, it’s a lot of people. But what they’re not getting, is a large portion of anyone much further away.Thus, the second location, located at 2nd and Madison. This new local area would ostensibly cover those working between Western and 4th (again), but now measured laterally from University to Columbia. With two locations, Pabla will now command the Indian lunch business for roughly nine blocks, all along 2nd Avenue. And though that might not seem like much, half that area of control has been enough to keep the original location profitable for the past 17 years.If you’re really interested in the math, check out the Lotka-Volterra equation–a basic predator/prey calculation that can easily be modified for the restaurant world.