APPENDIX Q — CE SPREADSHEET FOR BASE SCENARIO
APPENDIX Q — CE SPREADSHEETS FOR BASE SCENARIO
The Cost-Effectiveness (CE) spreadsheet in APPENDIX Q is the Base Scenario
spreadsheet, used for Table 17 and subsequently modified for the various CE
sensitivity analyses summarized in Tables 18 through 26. The percentage point
values assigned to different components of an EC, as well as the Elevation
Accuracy Multipliers for different technologies, at the bottom of the spreadsheet,
were all provided by FEMA during coordination meetings.
Evaluation of Alternatives in Obtaining Structural Elevation Data
Dewberry
A
B
C
D
E
F
G
H
I
J
K
Address Geocoding to get
Latitude/Longitude and BFEFEMA Building Diagram No.
Top of Bottom Floor (TBF) in A-zone,
Lowest Horiz Str. Member in V-zoneLAG and HAG ElevationsOther Elevations (garage and lowest
machinery)
Number and Area of Flood VentsTotal Percent Value of ECUsing available data, additional cost perstructure added to RegistryCE Ratio compared with $300 value of
ECs surveyed and entered in Registrywhen mass-produced community-wide
Maximum Possible Percentage Points 5 5 55 25 5 5 100 N/A N/A 0.25 K3
0. Surveyed EC's accurate lat/long, batch entry 5.0 5.0 55.0 25.0 5.0 5.0 100 $300 1.00 No offsets (columns D,F)
1. Digital EC's, no/inacc. lat/long, batch entry 0.0 5.0 55.0 25.0 5.0 5.0 95.0 $2.50 114.00 0.85 K5
2. Hardcopy EC's, no/inacc. lat/long, batch entry 0.0 5.0 55.0 25.0 5.0 5.0 95.0 $7.50 38.00 No footprints (LIDAR/IFSAR)
3. Hardcopy EC's, no/inacc. lat/long, 1 web entry 0.0 5.0 55.0 25.0 5.0 5.0 95.0 $15.00 19.00 0.80 K7 Can't easily identify address or
4. Hardcopy EC's accurate lat/long, 1 web entry 5.0 5.0 55.0 25.0 5.0 5.0 100 $15.00 20.00 Uncertain Bldg Diagram No.(Pictometry, VISAT)
5. Future EC's, no/inacc. lat/long, 1 web entry 0.0 5.0 55.0 25.0 5.0 5.0 95.0 $10.00 28.50 0.50 K9
6. Future EC's, accurate lat/long, 1 web entry 5.0 5.0 55.0 25.0 5.0 5.0 100 $10.00 30.00 Pictometry relative elevations (columns D,F)
7. Photogrammetry (2' CI), no offsets 0.0 0.0 9.5 17.2 0.9 0.0 27.5 $12.50 6.60 0.20 K11
8. Photogrammetry (2' CI), surveyor offsets 5.0 5.0 47.3 21.5 4.3 5.0 88.1 $62.50 4.23 VISAT measurement success (columns D,F)
9. Photogr.(2' CI) with footprints, owner offsets 5.0 5.0 47.3 21.5 4.3 5.0 88.1 $20.00 13.22 $35.00 K13
10 Photogrammetry (5' CI), no offsets 0.0 0.0 3.9 7.0 0.4 0.0 11.2 $12.50 2.69 VISAT Unit Costs
11. Photogrammetry (5' CI), surveyor offsets 5.0 5.0 19.3 8.8 1.8 5.0 44.8 $62.50 2.15 $5.00 K15
12. Pictometry with LIDAR DTM 0.0 4.0 18.9 17.2 1.7 0.0 41.8 $52.50 2.39 Unit cost to digitize EC's
13. LIDAR (2' CI), no footprints, no offsets 0.0 0.0 8.0 14.6 0.7 0.0 23.4 $12.50 5.61 $2.50 K17 unit cost for batch entry
14. LIDAR (2' CI) with footprints, no offsets 5.0 0.0 11.8 21.5 1.1 0.0 39.4 $7.50 15.76 $10.00 K18 unit cost for 1 web entry
15. LIDAR (2' CI), no footprints, surveyor offsets 5.0 5.0 40.2 18.3 3.7 5.0 77.1 $62.50 3.70 $10.00 K19
16. LIDAR (2' CI), no footprints, owner offsets/data 0.0 5.0 40.2 18.3 3.7 5.0 72.1 $20.00 10.82 Unit Costs for photogrammetric spot heights
17. LIDAR (2' CI) with footprints, surveyor offsets 5.0 5.0 47.3 21.5 4.3 5.0 88.1 $57.50 4.60 $50.00 K21
18. LIDAR (2' CI) with footprints, owner offsets/data 5.0 5.0 47.3 21.5 4.3 5.0 88.1 $15.00 17.62 Local surveyor cost for georeferencing/offsets etc.
19. IFSAR (10' CI) with footprints, surveyor offsets 5.0 5.0 0.0 0.0 0.0 5.0 15.0 $57.50 0.78 $300 K23
20. Photogrammetric Van (VISAT) 5.0 4.0 8.8 4.0 0.8 1.0 23.6 $37.50 1.89 Total unit cost of surveyed EC's in Registry
* Note: no "owner" method works without footprints, centroids or parcels linked to street addresses $50 K25
Conventional/GPS Survey Accuracy Multiplier = 1.00 0.50 ft at 95% confidence level Pictometry Unit Costs
2' CI Photogrammetry Accuracy Multiplier = 0.86 1.20 ft at 95% confidence level
when vertical accuracy =
This Base Spreadsheet is the basis of model
APPENDIX Q — Base Spreadsheet for
sensitivity analyses when parameters are
subjective or variable in different communities. The
Cost-Effectiveness (CE) Ratio and
most subjective parameters are elevation accuracy
Relative Value of Different Methods for
multipliers that determine relative value of lower
Generating Data for Elevation Registry
accuracy datasets, and parameters that weight the
relative value of Elevation Certificate components:
—
the value of lat/long linked to addresses (5%),
FEMA building diagram number (5%), TBF/LHSM
(55%), LAG/HAG (25%), elevation of garage and
Assumes value of elevations degrade
non-linearly to zero, becoming
worthless when 5% of elevations have
errors equal to or greater than 4 ft
lowest machinery (5%), number and area of flood
vents (5%). Other spreadsheets vary other model
parameters over their range of uncertainty to
determine minimum/maximum CE ratios.
when vertical accuracy =
5' CI Photogrammetry Accuracy Multiplier = 0.35 when vertical accuracy =
Pictometry (LIDAR DTM) Accuracy Multiplier = 0.86 when vertical accuracy = 1.20 ft at 95% confidence level
LIDAR Accuracy Multiplier (assuming 2' CI standard) = 0.86 when vertical accuracy =
$10,000 K27
3.00 ft at 95% confidence level CCS/county with no footprints (LIDAR)
$5,000 K29
1.20 ft at 95% confidence level D&D/county with footprints (LIDAR/IFSAR)
IFSAR Accuracy Multiplier (assuming 10' CI standard) = 0.00 when vertical accuracy = 6.00 ft at 95% confidence level 1000 K31
422
VISAT Photogrammetric Van Accuracy Multiplier = 0.80 when vertical accuracy = 1.50 ft at 95% confidence level Number of structures/county for LIDAR or IFSAR
Note: 2' CI = 1.2' accuracy at 95% confidence level; 5' CI = 3.0' accuracy at 95% confidence level
Base Scenario, Page 2
Elevation Accuracy Multipliers that degrade maximum value when less than best accuracy:
If 95% of elevations accurate within 6" 1.00 Assumed elevation accuracy of conventional or GPS surveys
If 95% of elevations accurate within 1' 0.90
If 95% of elevations accurate within 2' 0.70
If 95% of elevations accurate within 3' (5' contours) 0.35
If 95% of elevations accurate within 4' 0.00
If 95% of elevations accurate within 5' 0.00
If 95% of elevations accurate within 6' (10' contours) 0.00