Comparative Evaluation of Traffic Loads and Load Factors in the Design of Roadway Truss Bridges under International Standards


Authors : Mustafa K. Sadek; Nabil S. Mahmoud; Fikry A. Salem

Volume/Issue : Volume 10 - 2025, Issue 9 - September


Google Scholar : https://tinyurl.com/4d9jwwps

Scribd : https://tinyurl.com/ye3ktufm

DOI : https://doi.org/10.38124/ijisrt/25sep468

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Abstract : This study presents a comparative evaluation of traffic loads and load factors in the design of roadway bridges under three major international standards: AASHTO LRFD (2024), the Egyptian Code (2015), and Eurocode (EN 1991). The analysis highlights differences in lane width specifications, load model formulations, impact factor treatment, and fatigue assessment. AASHTO LRFD allows wider lanes (3.65 m) and employs independent impact factors, simplified fatigue models, and higher partial safety factors, emphasizing conservative yet straightforward design. The Egyptian Code adopts narrower lanes (3.0 m) with integrated impact effects and moderate safety factors, balancing serviceability and realism. Eurocode enforces stricter restrictions on loaded length and width, incorporates diverse load models including crowd and special vehicle loads and utilizes multiple fatigue models with moderate factors, providing high flexibility and accuracy. The study also compares tire contact areas, lane adjustment factors, and force application methods, revealing varying approaches to modeling braking and centrifugal forces. Overall, the findings illustrate the distinct philosophies of American, Egyptian, and European bridge design standards, offering insights for optimized and context-specific structural design.

Keywords : Traffic Load Modeling, Load Combinations Factors, Lane Adjustment Factors, Fatigue Loads, Impact Factors, AASHTO LRFD, Egyptian Code, Eurocode.

References :

  1. The Egyptian Code for the Planning, D., and Construction of Bridges and Overpasses – Part 4: Loads and Forces on Bridges and Overpasses (ECP 207-4:2015, The Egyptian Code for the Planning, Design, and Construction of Bridges and Overpasses – Part 4: Loads 2015.
  2. El-Kholy, A.M., H. Sayed, and A.A.J.A.S.E.J. Shaheen, Comparison of Egyptian Code 2012 with Eurocode 8-2013, IBC 2015 and UBC 1997 for seismic analysis of residential shear-walls RC buildings in Egypt. 2018. 9(4): p. 3425-3436.
  3. Lukić, M.J.P.S.I., Programme for maintenance and evolution of Eurocodes: Drafting of the future EN 1993-1-9 on fatigue of steel structures. 2019. 19: p. 655-664.
  4. AASHTO LRFD Bridge Design Specifications – 10th Edition. 10th Edition (2024), 2024.
  5. EN 1991-2:2023 – Eurocode 1: Actions on structures – Part 2: Traffic loads on bridges Actions on structures – Part 2: Traffic loads on bridges 2023.
  6. Barsom, J.M.J.E.F.M., Development of the AASHTO fracture-toughness requirements for bridge steels. 1975. 7(3): p. 605-618.
  7. Lantsoght, E.O., et al. Using Eurocodes and Aashto for assessing shear in slab bridges. in Proceedings of the Institution of Civil Engineers-Bridge Engineering. 2016. Thomas Telford Ltd.
  8. El-masry, A.A., S.A. Rabou, and M.J.I.I.S. Ghannam, Design resistance strengths of composite steel box girder bridge using different codes. 2024. 9(10): p. 369.
  9. Nowak, A.S., C.-H. Park, and J.R.J.S.s. Casas, Reliability analysis of prestressed concrete bridge girders: comparison of Eurocode, Spanish Norma IAP and AASHTO LRFD. 2001. 23(4): p. 331-344.
  10. Matar, H.B., M.M. Bakhoum, and I.I. Ishac. Comparison of Serviceability Limit State Code Requirements for Short and Medium Span Composite Bridges. in IABSE Symposium Report. International Association for Bridge and Structural Engineering. 2012.

This study presents a comparative evaluation of traffic loads and load factors in the design of roadway bridges under three major international standards: AASHTO LRFD (2024), the Egyptian Code (2015), and Eurocode (EN 1991). The analysis highlights differences in lane width specifications, load model formulations, impact factor treatment, and fatigue assessment. AASHTO LRFD allows wider lanes (3.65 m) and employs independent impact factors, simplified fatigue models, and higher partial safety factors, emphasizing conservative yet straightforward design. The Egyptian Code adopts narrower lanes (3.0 m) with integrated impact effects and moderate safety factors, balancing serviceability and realism. Eurocode enforces stricter restrictions on loaded length and width, incorporates diverse load models including crowd and special vehicle loads and utilizes multiple fatigue models with moderate factors, providing high flexibility and accuracy. The study also compares tire contact areas, lane adjustment factors, and force application methods, revealing varying approaches to modeling braking and centrifugal forces. Overall, the findings illustrate the distinct philosophies of American, Egyptian, and European bridge design standards, offering insights for optimized and context-specific structural design.

Keywords : Traffic Load Modeling, Load Combinations Factors, Lane Adjustment Factors, Fatigue Loads, Impact Factors, AASHTO LRFD, Egyptian Code, Eurocode.

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Paper Submission Last Date
31 - December - 2025

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