Y. Hassan et al., APPLICATION FOR AUTOMATED-DETERMINATION OF PASSING AND NO-PASSING ZONES - A CASE-STUDY, Canadian journal of civil engineering, 24(2), 1997, pp. 276-287
Currently, passing and no-passing zones are established using a graphi
cal technique and (or) field measurements. As an alternative, this art
icle presents an application of two computer programs, MARKS and MARKC
, developed by the authors to establish the marking of passing and no-
passing zones on two-dimensional (2-D) separate and three- dimensional
(3-D) combined highway alignments, respectively. Using a 7 km segment
on Highway 61, a four-phase study is conducted to show the applicabil
ity of the programs, to compare the 2-D and 3-D sight distances, to de
termine the marking of passing and no-passing zones according to curre
nt standards, and to determine the marking according to a revised pass
ing sight distance (PSD) model developed by the authors. The programs
are shown to be accurate and applicable to real highways, and use the
data that are already available in the highway agencies. A significant
difference between the 2-D and 3-D sight distances is shown to exist,
and therefore sight distance should be determined in 3-D combined ali
gnments rather than 2-D separate alignments. A considerable difference
is also shown between the markings according to current standards and
according to the revised PSD model. It is concluded that the implemen
tation of the developed software has the potential benefits of elimina
ting human errors, saving time and cost, providing greater flexibility
to designers to change the alignment and easily check the effect on p
assing zones, and transferring the decision of allowing or disallowing
passing on special circumstances From field crews to engineers. Also,
revisions of the current marking standards are recommended.