An Unrealistic Traffic Study

Isakson Living conducted a traffic study for their initial proposal for a 987-unit retirement community on the Tritt property, next to East Cobb Park.  That study (click here) includes traffic projections.  These projections were recently updated to reflect the 748 units in the latest proposal.  These projections also compare traffic to a 100 and 200 house subdivision on the same land (although we have outlined why 200 houses is highly unrealistic).

Traffic projections are supposed to conservative, meaning that if there are multiple legitimate techniques for calculating traffic, we take the one which shows the highest numbers.  We would not, for example, project traffic for an office complex proposal that assumes it is at partial occupancy.  We want to know the maximum amount of traffic possible.  Isakson Living's latest traffic projections were highly conservative in calculating the traffic for potential subdivisions, yet not conservative in  calculating the traffic for their Isakson Living East Cobb proposal.

To estimate traffic, the Institute of Transportation Engineers (ITE) Trip Generation Manual, 9th edition was used.  This manual has a number of land use categories - single family homes, senior adult housing, etc. - with traffic multipliers and/or formulas for each.

A subdivision would comprise the single family homes category, and this has two techniques to calculate traffic - simple multipliers and more complex formulas.  In this case, the formulas show more traffic, so Isakson Living used the formulas to estimate the traffic produced by a 100 and 200 house subdivision.  This is a conservative way to calculate traffic, even though 200 houses is not a viable scenario.

However, to calculate the traffic for their proposed Continuing Care Retirement Community (CCRC), Isakson Living chose land use categories which allow for unoccupied units, rather than the conservative approach of assuming the development will be fully occupied, and using the appropriate categories for fully occupied units.  This is like an office building developer conducting a traffic study which assumes that the offices will never be fully occupied.  And, that is just the beginning and the least of the problems with Isakson Living's traffic study.

The ITE manual has land use categories for CCRC, which is what Isakson Living's proposal is, yet they did not use the CCRC category.  We question why the CCRC category was not used.  ITE explicitly created this category for CCRCs, and conducted multiple traffic studies to come up with traffic multipliers.  If Isakson Living had used the CCRC category, it would have shown significantly more traffic, especially during the peak AM and PM rush hours.

Rather, Isakson Living broke down their proposal into its 3 constituent parts - Independent Living, Assisted Living and Nursing - and assigned an ITE category to each to estimate traffic.  87% of the units are Independent Living, and we question the choice of the ITE category for these units, something called a "Congregate Care Facility", which has very low traffic numbers, because vehicle ownership by the residents in that category is very low.  Isakson Living's initial traffic study quotes the ITE manual, which states "vehicle ownership levels were very low at congregate care facilities".  Would vehicle ownership be very low at Isakson Living East Cobb?  Lets look at the facts.

• We will assume for the sake of argument that very low vehicle ownership level means that fewer than 10% of residents own vehicles.  Is that true of Isakson Living's Park Springs community in Stone Mountain?  Probably 70% or 80% or more of the occupied independent living units own at least one vehicle, and Isakson Living has confirmed that residents can have more than one car.
  
  

• ITE recognizes that the affluence of the residents in senior facilities is one of the factors which increases traffic, and any senior who can afford to live at Isakson Living East Cobb can easily afford a car.
  
  

• The CCRC code in Cobb County requires one parking space per independent living unit, and half a parking space per assisted living or nursing unit.  Isakson Living was part of the 2008 committee which wrote the Cobb County CCRC code, and they would not build extra parking spaces if they were not needed.

• Isakson Living is required to build 700 parking spaces for the East Cobb proposal, but they are in fact building 882 spaces.  They recognize that their residents will own cars and drive, and that the facility will have many employees and visitors.  The traffic at a CCRC comes from residents, employees, visitors, services and deliveries.  Isakson Living's latest study shows 1,528 vehicle trips a days; driving to the facility counts as 1 trip, and driving away counts as another trip.  If each of the 882 parking spaces has just a single car leave and return per day, that is 1,764 trips a day, significantly more than the study indicates.  Why is Isakson Living building 882 parking spaces if daily traffic will be less than 2 trips per space?
  
  

• Owning and driving a car is part of being an independent senior.  A CCRC has many amenities, but seniors will want to drive.
  
  

• At Park Springs, residents can own golf carts, and can at least drive the golf carts to the adjacent Stone Mountain Golf Course.  Golf carts will not be allowed at the East Cobb facility, and their is no shopping within walking distance, so the seniors will drive.  A few may take shuttles offered by the facility, but many will choose to drive their own cars.

So, the Isakson Living traffic study is based on the premise that vehicle ownership is low among the residents, when in fact, it will likely be quite high.  This invalidates the traffic projections.

We disagree with the decision to not use the CCRC traffic category, and to split the CCRC into parts, but we especially disagree with the decision to use the "Congregate Care Facility" category, where the resident own few cars, to represent the independent living units.  A far more appropriate ITE category would be Senior Apartments, which is what these independent living units are.  The Senior Apartments category shows far more traffic for this proposal.

Isakson Living's 1999 proposal for a 456 unit CCRC in Athens, GA (which was defeated) was projected to generate 1,481 daily trips, according to the Athens media.  That is 3.25 daily trips per unit, as compared to just 2.04 daily trips for the Isakson Living East Cobb proposal.  Have seniors' driving habits changed that much in 15 years?  If anything, seniors are living longer, healthier lives, and driving for more of their lives.  The Athens traffic number appear to be much more realistic.