AP-G84/04 Best practice in road use data collection, analysis ... - WIM
AP-G84/04 Best practice in road use data collection, analysis ... - WIM
AP-G84/04 Best practice in road use data collection, analysis ... - WIM
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Accessed by AR - ARRB TRANSPORT RESEARCH on <strong>04</strong> Feb 2005<br />
<strong>AP</strong>PENDIX B – NUMBER OF AADT OBSERVATIONS<br />
Aust<strong>road</strong>s 20<strong>04</strong><br />
— 61 —<br />
<strong>Best</strong> Practices <strong>in</strong> Road Use Data Collection, Analysis and Report<strong>in</strong>g<br />
The recommended method of estimat<strong>in</strong>g the number of AADT observations required to calculate<br />
VKTij <strong>in</strong> any region i and <strong>in</strong> stratum j is as follows:<br />
Calculate the follow<strong>in</strong>g estimates from the most recent available <strong>data</strong>:<br />
VKT i<br />
SD<br />
ij<br />
L<br />
ij<br />
ni<br />
- amount of travel <strong>in</strong> region i (=∑ VKTij<br />
),<br />
j=<br />
1<br />
- standard deviation of the AADT observations <strong>in</strong> region i and stratum j,<br />
- total length of <strong>road</strong> <strong>in</strong> region i and stratum j,<br />
ni - the number of strata <strong>in</strong> region i.<br />
Calculate the required number of AADT observations <strong>in</strong> region i and stratum j us<strong>in</strong>g the follow<strong>in</strong>g<br />
expression (NAASRA 1982):<br />
N<br />
ij<br />
Lij<br />
SDij<br />
=<br />
( 0.<br />
05VKT<br />
)<br />
i<br />
ni<br />
2 ∑<br />
j=<br />
1<br />
L<br />
ij<br />
SD<br />
ij<br />
where:<br />
N<br />
ij<br />
is the required number of AADT observation <strong>in</strong> region i and stratum j.<br />
(Equation B1)<br />
An example calculation to illustrate the procedure is as shown <strong>in</strong> Table B1 with eight strata (ni = 8).<br />
The site is on a rural <strong>road</strong>. The estimates of VKTij, Lij and SDij are from exist<strong>in</strong>g <strong>in</strong>ventory <strong>data</strong> <strong>in</strong><br />
region i.<br />
AADT stratum<br />
j =1 to 8<br />
0-100<br />
101-300<br />
301-700<br />
701-1100<br />
1101-2000<br />
2001-4000<br />
4001-7000<br />
7000 plus<br />
VKT ij<br />
(×10 3 veh-km)<br />
2586<br />
2750<br />
3277<br />
2409<br />
3496<br />
4013<br />
2574<br />
2703<br />
Table B1 - Calculation of the Number of VKT Stations<br />
Inventory Data <strong>in</strong> Region i<br />
L<br />
ij<br />
(km)<br />
94821<br />
15275<br />
6931<br />
2699<br />
2310<br />
1428<br />
496<br />
275<br />
SD<br />
ij<br />
(veh)<br />
29<br />
60<br />
111<br />
110<br />
279<br />
543<br />
848<br />
2459<br />
L<br />
ij<br />
× SD<br />
ij<br />
(veh-km)<br />
2,749,809<br />
916,500<br />
769,341<br />
296,890<br />
644,490<br />
775,4<strong>04</strong><br />
420,608<br />
676,225<br />
No. of stations<br />
N ij<br />
14.07 (14)<br />
4.7 (5)<br />
3.94 (4)<br />
1.52 (2)<br />
3.30 (4)<br />
3.97 (4)<br />
2.15 (3)<br />
3.46 (4)<br />
Sum 23808 - - 7,249,267 40
Change language