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Figure 6 summarizes the results of the test. An im-
<br />portant qualification to the results is that the ob-
<br />served parking count (Column 4) does not
<br />necessarily represent a "design value" for the devel-
<br />opment. It is not known if each project was operat-
<br />ing at maximum levels of trip generation or if
<br />business volumes were significantly lower for the
<br />project due to the slow economy or other factors.
<br />Specifically, it is known that those projects exhibiting
<br />an unusually low actual accumulation were being af-
<br />fected by site factors. Projects 10, 11, 13, 1G, and 17
<br />were experiencing lower occupancy at hotel compo-
<br />nents. This is signtficant since the values in Column
<br />3 were computed assuming 100 percent occupancy.
<br />Further, same projects were surveyed assuming that
<br />all parking demand was beitlg served by oti-site facil-
<br />ities. Projects 13 and 15, however, tnay reflect a dif-
<br />ferent situation, since there is a substantial amount
<br />of "other" parking space available. For Project 13, it
<br />is known that such parking is used significantly by
<br />employees.
<br />Findings
<br />With the above qualifications in mind, Figure G in-
<br />dicates:
<br />• The parking demand estimated by adding the indi-
<br />vidual peaks produced results that were consis-
<br />tently high.
<br />• Estimating shared parking demand using time dif-
<br />ferentials will, if properly constructed, be more re-
<br />liable than estimating gross parking demand.
<br />• When conservative values are used for peak park-
<br />ing and hourly factors, estimated shared parking
<br />demand will be higher than actual parking ac-
<br />cumulation. In addition, there often times are
<br />other relationships, such as captive market effects,
<br />which lower aggregate parking demand.
<br /> Figu re 6
<br /> Results"'of Test Cases
<br /> 1 2 g 4 5 6 7
<br /> Percent of Percent
<br /> Estimated Estimated Overestimation Savings
<br /> Single-Use Typical Shared Observed Shared2 Gross
<br /> Gross Zoning Pazking Actual Gross Parking Peak
<br /> Peak Codet Peak Peak Peak Peak to
<br /> Accumulation Requirement Accumulation Accumulation to to Shared
<br />Mixed-Use Project Type (spaces) (spaces) (spaces) (spaces) Actual Actual Peak
<br />1. Office/Retail 5,749 5.858 5,229 5,570 3%n -6% 9%
<br />2. Office/Retail 2,936 3,744 2,788 2,352 25 19 6
<br />3. Office/Retail 772 900 617 G33 22 - 3 25
<br />4. Office/Retail 2,814 3,048 2,291 2,592 9 - 12 21
<br />5. Office/Retail 162 196 154 154 5 0 5
<br />6. Office/Entertainment 1,458 1,879 1,32G 1,163 25 14 11
<br />7. Office/Entertainment 812 1,O1G 714 464 75 54 21
<br />8. Office/Entertainment 1,724 2,112 1,501 614 181 144 37
<br />9. Office/Hotel 1,145 1,399 1,006 882 30 14 16
<br />10. Uffice/Hotell
<br />Entertainment 1,627 1,933 1,323 725 124 82 42
<br />11. Office/Hotell
<br />Entertainment 1,236 1,452 990 525 135 89 46
<br />12. Office/Hotel/
<br />Entertainment 784 862 659 809 -3 -19 -
<br />13. Office/Retail/H ote U
<br />Entertainment 8,316. 9,610 4,242 2,287 264 85 179
<br />14. Office/Retail/
<br />Entertainment 869 1,094 754 GDO 45 26 19
<br />15. Office/Retail/
<br />Entertainment 5,099 5,157 3,755 2,869 78 31 47
<br />16. Office/Hotell
<br />Entertainment 2,588 3,188 2,183 1,498 73 46 27
<br />17. Office/Hotel 1,125 1,34G 743 594 89 25 64
<br />t~>For this calculation, the following code standards were used: Ot~fice = 4.0 spaces per 1,000 square feet of GL A; retail = 4.0 or 5.U
<br />spaces per 1,000 feet of GLA (function of size); restaurant = 20 .0 spaces per 1,000 square feet of GL A; reside ntial = 1.0 spaces per
<br />dwelling unit; hotel = 1.0 spaces per room, with conference rooms at 0.5 spaces per seat.
<br />~2>Using results from Colum n 3.
<br />6 September 83/~ - ~ 31~~9
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