Basic Elements of Highway Traffic Analysis 97Road type Number of C’way width Peak-hour flow
lanes (m) (veh/h)
UAP1 2 6.10 1020
High standard single 2 6.75 1320
carriageway road carrying 2 7.30 1590
predominantly through traffic 2 9.00 1860
with limited access. 2/3 10.00 2010
3 12.30 2550
3/4 13.50 2800
4 14.60 3050
4 + 18.00 3300
UAP2 2 6.10 1020
Good standard single carriageway 2 6.75 1260
road with frontage access and 2 7.30 1470
more than two side roads per km 2 9.00 1550
2/3 10.00 1650
3 12.30 1700
3/4 13.50 1900
4 14.60 2100
4 + 18.00 2700
UAP3 2 6.10 900
Single carriageway road of variable 2 6.75 1100
standard with frontage access, 2 7.30 1300
side roads, bus stops and 2 9.00 1530
pedestrian crossing 2/3 10.00 1620
UAP4 2 6.10 750
Busy high street 2 6.75 900
carrying mostly local traffic with 2 7.30 1140
frontage activity (loading/ 2 9.00 1320
unloading included) 2/3 10.00 1410Table 4.15Design traffic flows for single carriageway urban roads (2-way)
monthly variations in flow. If available, continuous automatic traffic count data
may help identify periods of maximum flow.
In the case of proposed new highway schemes, the carriageway standard
chosen by means of Tables 4.15 to 4.17 should not be used as a design tool in
isolation; factors other than peak flows should be considered. Economic and
environmental factors must also be considered before a final decision is taken.
4.7 Expansion of 12 and 16-hour traffic counts into AADT flows,
In order to estimate the AADT for a given highway, it is not necessary to carry
out a traffic count over the entire 365-day period. Use of a count of limited time
duration will necessitate taking into account seasonal flow factors in order to
derive an AADT valuation. In particular, certain factors for expanding 12 and
16-hour counts to values of AADT are dependent on the type of roadway and