Establishing passing and no-passing zones has been a major task for highway agencies to ensure that neither safety nor highway capacity is compromised. Currently, no-passing zones are established using a graphical technique, based on two-dimensional (2-D) horizontal and vertical alignments, and (or) field measurements. As a result, this task has been time consuming, expensive, and subject to human errors. Moreover, decisions are taken by the field crew, and designers do not have flexibility to change the alignment and check the corresponding effect on passing zones. This article reviews analytical models developed by the authors for sight distance analysis on 2-D and 3-D highway alignments. Based on these models, two computer programs, MARKS and MARKC, are developed to determine the sight distance on 2-D separate and 3-D combined alignments, respectively. MARKS was verified graphically, and MARKC was verified using field measurements. The verification showed that the two programs can determine the available sight distance accurately. The implementation of the developed software has the potential benefits of eliminating human errors, saving time and cost, providing greater flexibility to designers to change the alignment and easily check the effect on passing zones, and transferring the decision of allowing or disallowing passing from field crews to engineers.

Additional Metadata
Keywords Combined alignment, Horizontal alignment, Passing zones, Sight distance, Vertical alignment
Journal Canadian Journal of Civil Engineering
Hassan, Y, Easa, S.M. (Said M.), & Halim, A.O. (1997). Automation of determining passing and no-passing zones on two-lane highways. Canadian Journal of Civil Engineering, 24(2), 263–275.