A mini review on percent time-spent-following (PTSF) as the service measure for two-lane highways

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Rama Rizana
Wael Alhajyaseen


Percent Time Spent Following (PTSF) is used by the Highway Capacity Manual (HCM) as one of the service measures to assess the level-of-service of two-lane highways since the 2000 edition. But, the problem facing to estimate this parameter is that the difficulty to measure it directly in the field. From several studies, it is known that the HCM analytical procedures applied in PTSF estimation produces inconsistent results with the 3 s surrogate measure and most of them are overestimate. This paper presents a review on estimating PTSF on two-lane highways from several studies that adopted HCM procedures.


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Rizana, R., & Alhajyaseen, W. (2018). A mini review on percent time-spent-following (PTSF) as the service measure for two-lane highways. Communications in Science and Technology, 3(2), 48-51. https://doi.org/10.21924/cst.3.2.2018.86


M. Cohen and A. Polus, Estimating percent-time-spent-following on two-lane rural highways, Transp. Res. Part C Emerg. Technol. 19 (2011) 1319–1325.

TRB, Highway Capacity Manual, 4th Editio. Washington D.C.: National Research Council, 2000.

TRB, Highway Capacity Manual, 5th Editio. Washington D.C.: National Research Council, 2010.

R. Luttinen, Percent time-spent-following as performance measure for two-lane highways, Transp. Res. Rec. 1776 (2001) 52–59.

D. L. Guell and M. R. Virkler, Capacity analysis of two-lane highways, Transp. Res. Board Natl. Acad. 1194 (1988) 199–205.

G. Johnson, Highway capacity manual misses mark on rural highway capacity, in Compendium of Technical Papers, Institute of Transportation Engineers 65th Annual Meeting, Denver, 1985.

I. Krumins and TAC, Two-lane highway capacity and level of service research project: Phase III final report, Ottawa, 1991.

R. Luttinen, Statistical properties of vehicle time headways, Transp. Res. Board 1365 (1992) 92–98.

A. Al-Kaisy and C. Durbin, Platooning on two-lane two-way highways: An empirical investigation, Procedia Soc. Behav. Sci. 16 (2011) 329–339.

G. M. Romana and I. Perez, Measure of effectiveness for level-of-service assessment of two-lane roads: an alternative proposal using a threshold speed, Transp. Res. Rec. 1998 (2006) 56–62.

A. Polus and M. Cohen, Theoretical and empirical relationships for the quality of flow and for a new level of service on two-lane highways, J. Transp. Eng. 135 (2009) 380–385.

N. I. Muttaka, C. P. Othman and M. Mushairry, Review of percent time spent following (PTSF) as performance measure for two-lane highways, J. Teknol. 64 (2013) 9–18.

A. Polus and M. A. Pollatschek, Criteria for widening of two-lane rural highways, Transp. Policy 11, (2004) 379–385.

J. E. Bessa and J. R. Setti, Derivation of ATS and PTSF functions for two-lane, rural highways in Brazil, Procedia Soc. Behav. Sci. 16 (2011)282–292.

C. Van As. and A. Van Niekerk. The operational analysis of two-lane rural highways, 23rd Southern African Transport Conference in South African Highway Capacity Research, 2007.

M. P. Dixon, S. S. K. Sarepali and K. A. Young, Field evaluation of highway capacity manual 2000 analysis procedures for two-lane highways, Transp. Res. Board 1802 (2002) 125–132.

A. Al-Kaisy and C. Durbin. Estimating percent time spent following on two-lane highways: field evaluation of new methodologies. 2007.

M. Shawky and I. Hashim, Impact of horizontal alignment on traffic performance at rural two-lane highways, in 4th International Symposium on Highway Geometric Design, 2010.

A. T. Moreno., C. Llorca, T. Sayed and A. Garcia, Field evaluation of traffic performance measures for two-lane highways in spain, Transp. Res. Circ. E-C190 (2014) 71–87.