Attachment 1 to Item 53 - Roadside Vegetation Management Plan

H AW K E S B U R Y C IT Y C O U N C IL R O AD S ID E V E G E T AT IO N M AN AG E M E N T P L AN
Two options were considered for the categories, including;
• Option 1: Breaking the combined scores/counts proportionally between the three categories
based on the number of roads assigned to each combined score/count; and
• Option 2: Breaking the combined scores/counts into three approximately equal categories
between 0 and 242.
Further analysis was undertaken into the two options to determine if they met the two requirements of
the maps listed above. Table 5 and Table 6 display the categories allocated for each option, along with
the number of polygons assigned to each category. The conservation priority ranking is shown in
Figure 2.
Table 5: Categories Assigned for Option 1
CATEGORY
(COMBINED
SCORE/COUNT)
NO. OF
ROADS
0-5 (Low) 271 (39 %)
6-7 (Medium) 200 (29 %)
8-242 (High) 229 (33 %)
Table 6: Categories Assigned for Option 2.
CATEGORY
(COMBINED
SCORE/COUNT)
NO. OF
ROADS
0-13 (Low) 628 (90 %)
14-28 (Medium) 55 (8 %)
29-242 (High) 17 (2 %)
Option 1 categories were determined by calculating the number of roads assigned to each combined
score/count, and then proportionally allocating (as evenly as possible) the combined scores/counts to a
category. The result is a much more even spread of combined scores/counts within each category.
Thus, 33 % of roads have been allocated to the High category, with 29 % and 39% allocated a Medium
and Low classification, respectively.
Option 2 categories were assigned by evenly grouping adjacent scores across the 0-242 range.
Therefore, each category represents approximately 14-15 scores. The categories assigned using
Option 2 are heavily biased towards the lower scores, with 90 % of roads being assigned a Low
category. At the other end of the scale, only 2 % of roads have been assigned to the High category.
The Medium category contained 8 % of roads.
From the analysis above it was decided that Option 2 would be used to generate the conservation
priority categories for roads. Option 2 better reflects the requirements of the conservation priority
analysis and the needs of HCC as it:
• More effectively differentiates the conservation priority of the polygons within rural roads
(based on the combined score/count); and
• Limits the range of combined score/counts per group.
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