Deflection is primarily a service issue and if you select the Optional Live Load Deflection Analysis option, in accordance with LRFD Art. 3.6.1.3.2, the deflection will be taken as the larger of the values resulting from:

Analysis is based on the line model of the structure and the live load deflection is then divided based on the ratio of the moments of inertia of the beam to the bridge multiplied by the distribution factors for that beam. These results are currently displayed on the printout under the camber and deflection results as Live Load Deflection.