A parametric study for varying span lengths is presented. It is assumed
that the cost and CO2 emissions are specified (Tables 1–4). The
primary economic (cost and CO2 emissions) and geometric characteristics
are examined. The results lead to practical rules for the preliminary
design of optimized PC precast road bridges, with a double U-shaped
cross-section and isostatic spans. The corresponding functions are
valid approximations within the range of the studied parameters, and
therefore, careful consideration is required when extrapolated.