For example, the traffic-engineering fraternity has developed some guidelines for hourly traffic volumes on various highway configurations, as shown, fairly typically, in the New Jersey standards (on the State Transportation website under Road User Cost Computations) which state that a typical modern two-lane highway has a vehicle capacity of 1400 privately-owned vehicles (POV's) per hour in each lane, which works out to, when multiplied by 24 hours, a fairly substantial 67,200 over a full day. That number is described by the NJ AoT as the "normal" and "ideal" capacity of such a highway, by which measure VT's two-lane Route 7 at about 15000/day would be, shall we say, under-utilized. For both lanes, 1400 times 2, then 2800 times 10 daylight hours yields a more old-fashioned once-standard number in the general 20-30K range. VT AoT data on Route 7 traffic in recent years have shown volumes in the 15-to-25K range at various points along its corridor, the higher counts in the urban areas like Rutland and the lower ones in the more-open areas like Ferrisburgh. I'd guess that the Ferrisburgh zoners could have obtained and used the relevant up-to-date Route 7 numbers as the quantitative basis for a traffic-congestion standard if they had wanted to. They didn't. Instead, they applied the adjective "inconclusive" to the COCO consultants' studies, without telling the public what numbers therein caused the "inconclusivity".
I have the column-inches for only one sample calculation, based in part on a little customer-time survey I ran, just for this purpose, at a fuel-and-food vendor site near here. It turns out that average on-site customer dwell-time is a shade over eight minutes, most at the pump and some at the coffee/snack counter. Because of typically larger fuel tanks, diesel fill-ups take somewhat longer than gas fill-ups for which I'll use the 8-minute figure. Hypothetically, there might be 8 pumps at a typical fuel-vendor set-up, each, under continuous use, capable of servicing almost 8 POV visits per hour, or about 64 for all. For the COCO proposal, that would be 64 POV's per hour coming off a Route 7 with a maximum hourly traffic flow of say 1500 (15000 for a full day divided by 10 daylight hours only) for a traffic impact of 64 divided by 1500, or about 4 percent. The estimate is conservatively high for three reasons: 1. it allocates all Route 7 traffic to daylight; 2. it doesn't recognize that it typically takes longer to fill up with diesel, so that traffic into and out of the fuel station would be reduced in accordance with the number of pumps dispensing diesel and not gas; and 3. it assumes all pumps would be in continuous customer use, something which hasn't happened since the gas lines of 1973. (Parenthetically, so much for the non-quantified notion that one reason for forbidding diesel pumps while permitting gas pumps is concern over increased traffic.)