TRAFFIC LOADING

1
TRAFFIC LOADING ESTIMATED FROM COUNTS
M Slavik J Bosman
2

• Data

Collect
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Collect New Data
Organise
Make Accessible
Analyse
Apply
Retrieve
Knowledge
2
3

• 70 freight by road
• 4 p.a. growth
• Information on traffic loading
• needed for
• pavement design
• road maintenance
• law enforcement
• statistics, patterns, trends

4

• SOURCES OF TRAFFIC LOADING
• INFORMATION
• Inductive-loop counters
• Weigh-In-Motion (WIM)
• Weighbridges

5

• ASPECTS OF TRAFFIC LOADING
• Magnitude
• Average Daily Traffic (ADT)
• Average Daily Truck Traffic (ADTT)
• Composition
• LV, HV HV - short, medium, long,
• buses, vehicle / axle configuration
• Axle loads
• Axle-load distribution
• ESAL (E80)

6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18

• E80 FROM INDUCTIVE LOOPS
• Bosman 1988
• 4 classes of road, by of 2-ax HV
• Typical (default) axle-load distributions
• Bosman 2004
• Simplified to 3 classes
• Slavik Bosman in 2006
• Parameters measurable by loops
• HV - Short, Medium, Long, vs E80/HV
• Influence of law enforcement
• 3 steps

19

• STEP 1 RELATION WITH E80/HV
• Loop measured attributes
• heavy vehicles (HV)
• short HV
• mediun HV
• long HV

20

• STEP 2 76 WIM STATIONS, 2005
• Data validated
• Reprocessed
• Long trucks determined
• E80/HV evaluated

21

• STEP 3 LAW ENFORCEMENT
• INTENSITY
• Strong permanent presence
• Medium ad-hoc, blitzes
• Weak occasional non-existent
• STEPS 1 2 3 GRAPH FIG.1

22
(No Transcript)
23
STEP 4 TRAFFIC LOADING MODELS Type LT class
Law Enf. 1 Below 35
Any 2 35 55 Weak 3 35
55 Strong 4 Over 55 Weak
5 Over 55 Strong
24
STEP 5 FIVE MODEL STATIONS Type LT
LE Model 1 Below 35 Any
N12 Kliprivier 2 35 55 Weak
N2 Winkelspruit 3 35 55 Strong
N4 Komati 4 Over 55 Weak N3
Hidcote 5 Over 55 Strong N3
Heidelberg
25
TABLE 2. Traffic and Sample Sizes at the Five
Traffic-loading Model Stations
26
TABLE 3. Key Figures of the Five
Traffic-loading Types
27
1 - N12 KLIPRIVIER
28
2 - N2 WINKELSPRUIT
29
3 - N4 KOMATIPOORT
30
4 - N3 HIDCOTE
31
5 - N3 HEIDELBERG
32
(No Transcript)
33
(No Transcript)
34
(No Transcript)
35

• WHY?
• Weak relationship between LT and E80/HV
• Imprecision of WIM due to
• - Calibration problems
• - Deteriorating pavement
• - Hardware and software defects
• No cheap substitute for good WIM measurements
• NEXT?
• Strict WIM quality control (European Standard)
• Uniform data validation procedures
• Uniform tender requirements
• Re-appraise situation in 2-3 years time

36

• CONCLUSION
• The relationship between the percentage of long
  trucks and E80/HV is not very good. R-square
  varies from 0,16 to 0,66.
• The trend lines, however, indicate that
• the E80/HV is lower with higher law
  enforcement, and
• the E80/HV is higher with a higher percentage
  of long trucks.
• It is thus recommended that, in the absence of
  better traffic loading data
• the E80/HV values in Table 3 of the paper, and
• the axle distributions in Appendix A of the
  paper
• be used by designers and practitioners in the
  meantime.

37

• ACKNOWLEDGEMENTS
• The authors wish to express their gratitude to
• NTRV (Northern Toll Road Venture, the N1 Toll
  Road Concessionaire)
• N3TC (N3 Toll Concession, the N3 Toll Road
  Concessionaire),
• TRAC (Trans African Concessions, the N4 Toll
  Road Concessionaire),
• Bakwena (the N4 Platinum Toll Road
  Concessionaire), and
• SANRAL (South African National Roads Agency
  Limited)
• for the traffic data and information made
  available.

38
TRAFFIC LOADING ESTIMATED FROM COUNTS
M Slavik J Bosman
39
(No Transcript)
40
(No Transcript)
41
(No Transcript)
42
(No Transcript)
43
(No Transcript)
44
(No Transcript)
45

• FACTS
• Bad news
• Too dispersed - bottom of a birds cage
• Good news
• Red line above green line
• All lines rising from left to right
• Blue line joins green on left, red on right

46
TABLE 1. Five Traffic-loading Model WIM
Stations