Area-Type Adjustment Factors for Non-CBD Signalised Intersections

Abena Agyeiwaa Obiri-Yeboah; Yaw Adubofour Tuffour; Mohammed Salifu

doi:doi:10.11648/j.ajce.20170502.17

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Area-Type Adjustment Factors for Non-CBD Signalised Intersections

Abena Agyeiwaa Obiri-Yeboah, Yaw Adubofour Tuffour, Mohammed Salifu

Received: 28 October 2016 Accepted: 4 January 2017 Published: 4 March 2017

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Abstract

In the estimation of saturation flow at signalized intersections using the HCM model, the influence of area-type characteristics on flow is accounted for by the area-type adjustment factor (f_a). The recommendation by the manual to use f_a=0.9 for CBD-intersections and 1.0 for all others tacitly assumes that the nature of non-CBD areas does not influence flow. This may not hold for many developing country cities and metropolitan areas where the roadside environments associated with non-CBD intersections may be laden with a flurry of activities that impact traffic flow. For signalized intersections in such areas, the HCM-recommended area-type adjustment factor could lead to over-estimation of saturation flow rates if the activities create substantial roadside friction to flow. This study set out to develop area-type adjustment factors for non-CBD signalized intersections located within the Kumasi Metropolis in Ghana, to accurately reflect the impact of roadside character on saturation flow rates. Using field saturation flow data collected at selected signalized intersections in the metropolis, area-type adjustment factors were developed for three distinct roadside friction environments categorised in the study as low/none, medium, and high. Average f_a values developed were 0.99 for low/none, 0.98 for medium, and 0.94 for high roadside friction environments. Also, a multiple linear regression model that attempts to relate f_a to pedestrian traffic interfering with flow within the environment of the intersection was developed as an alternative procedure for determining site specific area-type adjustment factor. It is recommended to use the f_a values developed in this study in the HCM saturation flow model in order to estimate more accurately the saturation flow rates at non-CBD signalized intersections within the Kumasi Metropolis.

DOI	10.11648/j.ajce.20170502.17
Published in	American Journal of Civil Engineering (Volume 5, Issue 2, March 2017)
Page(s)	119-123
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2024. Published by Science Publishing Group

Keywords

Area-Type Adjustment Factor, Non-CBD Signalised Intersections, Saturation Flow, Roadside Friction

References

[1]	Highway Capacity Manual (2010). Transportation Research Board, National Research Council, Washington, DC.
[2]	Shao, C. and Liu, X. M. (2011). “Study on the Saturation Flow Rate and Its Influence Factors at Signalised Intersections in China”, Procedia Social and Behavioral Sciences, 16 (2011) 504-514.
[3]	Rahman, M. and Nakamura, F. (2005). “Measuring passenger car equivalents for non-motorized vehicle (Rickshaws) at mid-block sections”. Journal of the Eastern Asia Society for Transportation Studies, 6: 119-126.
[4]	Chiguma, M. L. M. (2007). “Analysis of Side Friction Impacts on Urban Road Links: case study, Dar-es-Salaam”, Doctoral Thesis, Royal Institute of Technology, Stockholm, Sweden.
[5]	Le, X., Lu, J. J, Mierzejewski, E. A. and Zhou, Y. (2000). “Variations in Capacity at Signalized Intersections with Different Area Types”. Transportation Research Record 1710, Paper No 00-1664, pp 199-204.
[6]	Bonneson, J., Nevers, B., Zeeger, J., Nguyen, T. and Fong, F. (2005). “Guidelines for Quantifying the Influence of Area Type and other Factors on Saturation Flow Rates”, Texas Transportation Research Institute, Project No. PR385-V2, June, 2005.
[7]	Obiri-Yeboah, A. A. (2015). Development of Area-Type Adjustment Factors for Saturation Flow Estimation at Signalized Intersections in Kumasi. Doctoral Thesis, College of Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
[8]	Tarko, A. and Tracz, M. (2000). Uncertainty in Saturation Flow Predictions, Proceedings of Fourth International Symposium on Highway Safety, June 27-July 1, Maui, Hawaii, published as Transportation Research Circular E-C018, Transportation Research Board, National Research Council, Washington, D. C., pp. 310-321.
[9]	Obiri-Yeboah, A. A., Tuffour, Y. A. and Salifu, M. (2014). “Passenger Car Equivalents at Signalised Intersections within the Kumasi Metropolis in Ghana”. IOSR Journal of Engineering, 4 (4): 24-29.
[10]	Tuffour, Y. A., Obiri-Yeboah, A. A., Salifu, M. and Acquah, P. C. (2014). “Adjusting for the Effect of Bus Blockage on Saturation Flow Rates”. International Journal of Science and Research (IJSR), 3 (6): 749-753.

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APA Style

Abena Agyeiwaa Obiri-Yeboah, Yaw Adubofour Tuffour, Mohammed Salifu. (2017). Area-Type Adjustment Factors for Non-CBD Signalised Intersections. American Journal of Civil Engineering, 5(2), 119-123. https://doi.org/10.11648/j.ajce.20170502.17

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ACS Style

Abena Agyeiwaa Obiri-Yeboah; Yaw Adubofour Tuffour; Mohammed Salifu. Area-Type Adjustment Factors for Non-CBD Signalised Intersections. Am. J. Civ. Eng. 2017, 5(2), 119-123. doi: 10.11648/j.ajce.20170502.17

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AMA Style

Abena Agyeiwaa Obiri-Yeboah, Yaw Adubofour Tuffour, Mohammed Salifu. Area-Type Adjustment Factors for Non-CBD Signalised Intersections. Am J Civ Eng. 2017;5(2):119-123. doi: 10.11648/j.ajce.20170502.17

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@article{10.11648/j.ajce.20170502.17,
  author = {Abena Agyeiwaa Obiri-Yeboah and Yaw Adubofour Tuffour and Mohammed Salifu},
  title = {Area-Type Adjustment Factors for Non-CBD Signalised Intersections},
  journal = {American Journal of Civil Engineering},
  volume = {5},
  number = {2},
  pages = {119-123},
  doi = {10.11648/j.ajce.20170502.17},
  url = {https://doi.org/10.11648/j.ajce.20170502.17},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajce.20170502.17},
  abstract = {In the estimation of saturation flow at signalized intersections using the HCM model, the influence of area-type characteristics on flow is accounted for by the area-type adjustment factor (fa). The recommendation by the manual to use fa=0.9 for CBD-intersections and 1.0 for all others tacitly assumes that the nature of non-CBD areas does not influence flow. This may not hold for many developing country cities and metropolitan areas where the roadside environments associated with non-CBD intersections may be laden with a flurry of activities that impact traffic flow. For signalized intersections in such areas, the HCM-recommended area-type adjustment factor could lead to over-estimation of saturation flow rates if the activities create substantial roadside friction to flow. This study set out to develop area-type adjustment factors for non-CBD signalized intersections located within the Kumasi Metropolis in Ghana, to accurately reflect the impact of roadside character on saturation flow rates. Using field saturation flow data collected at selected signalized intersections in the metropolis, area-type adjustment factors were developed for three distinct roadside friction environments categorised in the study as low/none, medium, and high. Average fa values developed were 0.99 for low/none, 0.98 for medium, and 0.94 for high roadside friction environments. Also, a multiple linear regression model that attempts to relate fa  to pedestrian traffic interfering with flow within the environment of the intersection was developed as an alternative procedure for determining site specific area-type adjustment factor. It is recommended to use the fa values developed in this study in the HCM saturation flow model in order to estimate more accurately the saturation flow rates at non-CBD signalized intersections within the Kumasi Metropolis.},
 year = {2017}
}

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TY  - JOUR
T1  - Area-Type Adjustment Factors for Non-CBD Signalised Intersections
AU  - Abena Agyeiwaa Obiri-Yeboah
AU  - Yaw Adubofour Tuffour
AU  - Mohammed Salifu
Y1  - 2017/03/04
PY  - 2017
N1  - https://doi.org/10.11648/j.ajce.20170502.17
DO  - 10.11648/j.ajce.20170502.17
T2  - American Journal of Civil Engineering
JF  - American Journal of Civil Engineering
JO  - American Journal of Civil Engineering
SP  - 119
EP  - 123
PB  - Science Publishing Group
SN  - 2330-8737
UR  - https://doi.org/10.11648/j.ajce.20170502.17
AB  - In the estimation of saturation flow at signalized intersections using the HCM model, the influence of area-type characteristics on flow is accounted for by the area-type adjustment factor (fa). The recommendation by the manual to use fa=0.9 for CBD-intersections and 1.0 for all others tacitly assumes that the nature of non-CBD areas does not influence flow. This may not hold for many developing country cities and metropolitan areas where the roadside environments associated with non-CBD intersections may be laden with a flurry of activities that impact traffic flow. For signalized intersections in such areas, the HCM-recommended area-type adjustment factor could lead to over-estimation of saturation flow rates if the activities create substantial roadside friction to flow. This study set out to develop area-type adjustment factors for non-CBD signalized intersections located within the Kumasi Metropolis in Ghana, to accurately reflect the impact of roadside character on saturation flow rates. Using field saturation flow data collected at selected signalized intersections in the metropolis, area-type adjustment factors were developed for three distinct roadside friction environments categorised in the study as low/none, medium, and high. Average fa values developed were 0.99 for low/none, 0.98 for medium, and 0.94 for high roadside friction environments. Also, a multiple linear regression model that attempts to relate fa  to pedestrian traffic interfering with flow within the environment of the intersection was developed as an alternative procedure for determining site specific area-type adjustment factor. It is recommended to use the fa values developed in this study in the HCM saturation flow model in order to estimate more accurately the saturation flow rates at non-CBD signalized intersections within the Kumasi Metropolis.
VL  - 5
IS  - 2
ER  -

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Author Information

Abena Agyeiwaa Obiri-Yeboah

Department of Civil Engineering, Kumasi Polytechnic, Kumasi, Ghana
Yaw Adubofour Tuffour

Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
Mohammed Salifu

Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

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APA Style

Abena Agyeiwaa Obiri-Yeboah, Yaw Adubofour Tuffour, Mohammed Salifu. (2017). Area-Type Adjustment Factors for Non-CBD Signalised Intersections. American Journal of Civil Engineering, 5(2), 119-123. https://doi.org/10.11648/j.ajce.20170502.17

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ACS Style

Abena Agyeiwaa Obiri-Yeboah; Yaw Adubofour Tuffour; Mohammed Salifu. Area-Type Adjustment Factors for Non-CBD Signalised Intersections. Am. J. Civ. Eng. 2017, 5(2), 119-123. doi: 10.11648/j.ajce.20170502.17

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AMA Style

Abena Agyeiwaa Obiri-Yeboah, Yaw Adubofour Tuffour, Mohammed Salifu. Area-Type Adjustment Factors for Non-CBD Signalised Intersections. Am J Civ Eng. 2017;5(2):119-123. doi: 10.11648/j.ajce.20170502.17

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@article{10.11648/j.ajce.20170502.17,
  author = {Abena Agyeiwaa Obiri-Yeboah and Yaw Adubofour Tuffour and Mohammed Salifu},
  title = {Area-Type Adjustment Factors for Non-CBD Signalised Intersections},
  journal = {American Journal of Civil Engineering},
  volume = {5},
  number = {2},
  pages = {119-123},
  doi = {10.11648/j.ajce.20170502.17},
  url = {https://doi.org/10.11648/j.ajce.20170502.17},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajce.20170502.17},
  abstract = {In the estimation of saturation flow at signalized intersections using the HCM model, the influence of area-type characteristics on flow is accounted for by the area-type adjustment factor (fa). The recommendation by the manual to use fa=0.9 for CBD-intersections and 1.0 for all others tacitly assumes that the nature of non-CBD areas does not influence flow. This may not hold for many developing country cities and metropolitan areas where the roadside environments associated with non-CBD intersections may be laden with a flurry of activities that impact traffic flow. For signalized intersections in such areas, the HCM-recommended area-type adjustment factor could lead to over-estimation of saturation flow rates if the activities create substantial roadside friction to flow. This study set out to develop area-type adjustment factors for non-CBD signalized intersections located within the Kumasi Metropolis in Ghana, to accurately reflect the impact of roadside character on saturation flow rates. Using field saturation flow data collected at selected signalized intersections in the metropolis, area-type adjustment factors were developed for three distinct roadside friction environments categorised in the study as low/none, medium, and high. Average fa values developed were 0.99 for low/none, 0.98 for medium, and 0.94 for high roadside friction environments. Also, a multiple linear regression model that attempts to relate fa  to pedestrian traffic interfering with flow within the environment of the intersection was developed as an alternative procedure for determining site specific area-type adjustment factor. It is recommended to use the fa values developed in this study in the HCM saturation flow model in order to estimate more accurately the saturation flow rates at non-CBD signalized intersections within the Kumasi Metropolis.},
 year = {2017}
}

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TY  - JOUR
T1  - Area-Type Adjustment Factors for Non-CBD Signalised Intersections
AU  - Abena Agyeiwaa Obiri-Yeboah
AU  - Yaw Adubofour Tuffour
AU  - Mohammed Salifu
Y1  - 2017/03/04
PY  - 2017
N1  - https://doi.org/10.11648/j.ajce.20170502.17
DO  - 10.11648/j.ajce.20170502.17
T2  - American Journal of Civil Engineering
JF  - American Journal of Civil Engineering
JO  - American Journal of Civil Engineering
SP  - 119
EP  - 123
PB  - Science Publishing Group
SN  - 2330-8737
UR  - https://doi.org/10.11648/j.ajce.20170502.17
AB  - In the estimation of saturation flow at signalized intersections using the HCM model, the influence of area-type characteristics on flow is accounted for by the area-type adjustment factor (fa). The recommendation by the manual to use fa=0.9 for CBD-intersections and 1.0 for all others tacitly assumes that the nature of non-CBD areas does not influence flow. This may not hold for many developing country cities and metropolitan areas where the roadside environments associated with non-CBD intersections may be laden with a flurry of activities that impact traffic flow. For signalized intersections in such areas, the HCM-recommended area-type adjustment factor could lead to over-estimation of saturation flow rates if the activities create substantial roadside friction to flow. This study set out to develop area-type adjustment factors for non-CBD signalized intersections located within the Kumasi Metropolis in Ghana, to accurately reflect the impact of roadside character on saturation flow rates. Using field saturation flow data collected at selected signalized intersections in the metropolis, area-type adjustment factors were developed for three distinct roadside friction environments categorised in the study as low/none, medium, and high. Average fa values developed were 0.99 for low/none, 0.98 for medium, and 0.94 for high roadside friction environments. Also, a multiple linear regression model that attempts to relate fa  to pedestrian traffic interfering with flow within the environment of the intersection was developed as an alternative procedure for determining site specific area-type adjustment factor. It is recommended to use the fa values developed in this study in the HCM saturation flow model in order to estimate more accurately the saturation flow rates at non-CBD signalized intersections within the Kumasi Metropolis.
VL  - 5
IS  - 2
ER  -

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