General
Influence surface coefficients are the numerical values used to determine the influence of a unit load on a specific point of a structure, based on its position and orientation. These coefficients represent the contribution of a unit load at a specific point to the total response of the structure.
...
To ensure that the model runs without any issues, it is convenient and faster to start with larger numbers for both longitudinal and transverse unit load spacing. For instance, using 20 feet in the longitudinal direction and 10 feet in the transverse direction can be a good starting point. Once you have confirmed that the model runs smoothly and have reviewed the design report, you can proceed with a spacing value of 10 feet in the longitudinal direction and 6 feet in the transverse direction to check your design. After finalizing your design, it is recommended to perform another check using a spacing of 5-10 feet in the longitudinal direction and 3 feet in the transverse direction.
...
Centrifugal
Highway Design Speed [ft/second]: Highway design speed shall not be taken to be less than the value specified in the current edition of the AASHTO publication, A Policy of Geometric Design of Highways and Streets. 1.0 ft/s = 0.682 mph
...