Traffic - - Additional Details
The big picture as stated by a senior county commissioner: “is not whether it’s 24,900 or 42,000 cars per day, but rather that either number is so large that it will crush the homeowners in the area.” (A paraphrase - - he also knew that 8,000 cars per day would result from 99% residential development).
KCR.org initially estimated that the total traffic count could be 42,700 cars/day using ITE codes from Institute of Transportation Engineers Trip Generation Manual 7th edition. When we first heard the 24,900 number at a meeting with the developer, we asked for the details and were promised OK - - - they were never sent.
In early September, we found out that the developer’s site plan on file in the planning department overstated the total commercial/office square footage we used by 10%, and also understated the office component which generates less traffic then commercial. Both the developer and planning department errors raised our initial numbers higher than actual.
In a meeting 2 weeks before the final hearing, Mr. Harrell, after hearing KCR.org’s comments, requested that the traffic engineer (who was hired by the developer) to add in about 4,000 cars per day by using 102 cars/1000sq ft for the 65,000 grocery store in lieu of 41.5 cars/day for general commercial.
Apparently Mr. Harrell forgot this as he has continued to quote “only” 24,900 cars per day.
One must understand that this traffic estimation is very much an interpretative exercise:
- The developer’s traffic engineer used 41.5 versus 42.9 cars/1000 sq ft which is the standard ITE rate for commercial code 820.
- The same engineer decided not to use the 102 cars/1000 sq ft for the grocery store “because there were not enough samples”. Mr Harrell understood the flaw, but now seems “forgetful”.
- For the 8 outparcels, the engineer used 41.5 cars/1,000 sq ft rather then the much higher numbers for fast food (496 cars/1000), drive in banks (411 cars/1000), and pharmacies (88 cars/1000).
- The same engineer chose to use a “mixed use” 13.3% deduction factor which reduced total projected traffic even though an extensive study is underway on this topic because highly recognized specialists are stating that use of current mixed use data is “little more then exercises in speculation.” (Ewing, R., M Deanna, and S.C. U, Transportation Record 1518,pp 1-6)
In summary, it is our best objective estimate (recognizing we are not employed by anyone), ZA 3411 will generate at least 32,000 cars/day - - - 4 times the 8,000 cars/day from a 99% residential development had Mr. Harrell voted as his homeowner citizens requested.