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Appendix C: Identifying the Road Use Category (or Traffic Pattern Control Group)

Adapted from Transfund New Zealand Research Report 205.

Identifying the traffic pattern control group

The procedure to identify the road use category (or traffic pattern control group) in order to estimate the AADT is given below. Note that this procedure is unchanged from the original guide apart from the removal of the previous single site group 4 since it appears (for Auckland city at least) that the traffic pattern on urban residential streets emulates that on urban arterials.

Step Action

1
  • Determine a typical weekday interpeak/peak ratio, where the interpeak is the 12-1 pm hourly flow.
  • Determine the interpeak - time 'gap' between morning and afternoon peak hour flows (e.g. 17.15-08.45 = 8.5 hours).

Examine the below to determine the correct group(s) based primarily on the two attributes determined above, with the group descriptor label as an initial guide only.

2

If it is still unclear what the control group is then:

  • plot the hourly flows for each day of the week (and perhaps average Monday-Thursday)
  • compare with typical plots and choose a control group as appropriate.

3

If it is still unclear what the control group is then:

  • repeat the count, and/or
  • try each possible group when estimating the AADT, AADT error etc (average the results).

Group, descriptor label 12-1 pm/peak ratio

Interpeak

Monday-Thursday
Two-way

% AADT

Sun peak
Two-way

Monday-Thursday
Two-way 		Friday
One way

1a Urban arterial (a)

0.45-0.60

0.30-0.55

8.5-10.0

5.5-7.5

1b Urban arterial (b)

0.60-0.85

0.50-0.90

6.0-9.0

5.0-9.0

2 Urban commercial

0.80-0.85

0.70-1.00

2.0-4.0

5-9

3 Urban industrial

0.65-0.90

0.55-1.00

4.0-9.0

0-5

5 Rural urban fringe

0.50-0.70

0.30-0.80

8.0-10.0

10-24

6a Rural strategic (a)

0.65-0.90

0.40-0.95

4.0-8.0

7-14

6b Rural strategic (b)

0.80-0.95

0.45-0.95

4.0-7.0

9-17

7a Rural 'summer' recreation

0.85-1.00

0.50-1.00

2.0-4.0

10-19

7b Rural 'winter' recreation

0.90-1.00

0.35-1.00

2.0-4.0

10-30
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