This study analyzes the seismic response of traffic light poles, considering soil-foundation effects through nonlinear static and time history analyses. Two poles are investigated, uni-directional and bi-directional, each with 9 m mast arms. Finite element models incorporate the poles, soil, and concrete foundations for analysis. Results show that the initial stiffness of the traffic light poles decreases by approximately 38% due to soil effects, and the drift ratio at which their nonlinear behavior occurs is 77% of scenarios without considering soil effects. The maximum acceleration response increases by about 82% for uni-directional poles and 73% for bi-directional poles, while displacement response increases by approximately 10% for uni-directional and 16% for bi-directional poles when considering soil-foundation effects. Additionally, increasing ground motion intensity reduces soil restraints, making significant rotational displacement the dominant response mechanism over flexural displacement for the traffic light poles. These findings underscore the importance of considering soil-foundation interactions in analyzing the seismic behavior of traffic light poles and provide valuable insights to enhance their seismic resilience and safety.

The seismic responses of traffic light poles are investigated using a finite element analysis. Among the traffic light poles, single- and bi-directional traffic light poles are considered since such poles are frequently installed on vehicle roads. For a more detailed investigation, three different lengths of the mast arm are considered for each directional pole. For a time-history analysis, six actual and two artificial earthquakes are considered and applied to each direction of the poles (x and y) to investigate which direction input provides more significant responses due to the unsymmetrical structural shape. Herein, the x and y directions are respectively parallel and perpendicular based on the single mast pole case. From the analysis results, the average maximum displacement response is developed with the x-direction input case for both types of light poles. Also, the bi-directional traffic light poles show a 13% larger response than the single-directional traffic light poles. Even though the y-direction input case produces a smaller response, the response difference between the single- and bi-directional light poles considerably increases by about 60%. The average maximum acceleration responses are almost similar for both types of light poles.

As a preparation of a design standard regarding road facilities in terms of reliability based optimum design examples, such as cantilever columns for traffic lights, optimum design in deterministic and probabilistic ways for the foundation of traffic lights poles are proposed. Most of the previous study have focused on the foundation surrounded by cohesionless soil. However, the design would be governed by risky condition. Therefore the resistance by clay-soil is investigated compared with other design specifications. In deterministic optimization, GRG method is applied. It is found that both geometries of deep and shallow foundation provides optimum values. The resistance of cohesive soil is selected to represent the ultimate limit states, in terms of sliding, overturning and bearing pressures from super structures to the foundation under external loads. Example foundations with varying height of columns for traffic lights are optimized about 30% decreased embedded depth of foundation. The optimum coefficients of resistant and load factors may need to be developed with design load combinations in order to prepare design specifications as the next step.

In this study, spectral transmittance of signal lights (red, green, and yellow) through each colored lens was measured in other to examine changes in color sense of traffic lights according to color (red, yellow, green, blue, brown, and black) and coloring time (30 sec, 1 min, 5 min, 10 min, 20 min, and 30 min) of plastic tinted lens. The results were as follows ; Spectral transmittance distribution of a red light through lenses having different coloring time for each color (red, yellow, green, blue, brown, and black), study at the lowest value in the range of wave length 580-585 nm through red, yellow, green and blue lenses. The minimum value through brown lens was found at 55 0-600 nm, and at 570-590 nm through black one. Spectral in transmittance distribution of a yellow light through lenses with various coloring time for each color (red, yellow, green, blue, brown and black) stood at the minimum value showed at wavelength 540 nm through red, yellow, and green lenses and at 540- 670 nm through blue, brown, and black lenses. In the examination on spectral transmittance distribution of a green light through lenses having diverse coloring time for each color (red, yellow, green, blue, brown, and black), results appeared similar regardless of color and transmittance was lower less than 15% at the long-wavelength part over 600 nm. The dominant wavelengths of traffic lights according to each tinted lens were calculated as follows. The dominant wavelength of a red light was measured at 665-669 nm in red and yellow lenses, at 669-679 nm in green and blue lenses, at 664-676 nm in brown lens, and at 672-677 nm in black lens. The dominant wavelength of a yellow light showed at 565-558 nm in red lens, at 548-535 nm in yellow lens, at 540-576 nm in green lens, at 549-579 nm in blue lens, at 518 - 575nm in brown lens, and at 566-576 nm in black lens. The dominant wavelength of a green light appeared at 484-472 nm in red lens, at 487-485 nm in yellow lens, at 491-479 nm in green lens, at 490-484 nm in blue lens, at 490- 476 nm in brown lens, and at 483-477 nm in black lens.