Severe performance degradation of Global Navigation Satellite Systems (GNSS) is produced in urban scenarios, mainly due to dense multipath and non-line-of-sight (NLoS) conditions. Thus, the integration of GNSS with additional positioning systems, such as the location methods in Long Term Evolution (LTE) cellular systems, may cope with these challenging scenarios. This work proposes a generic evaluation model to assess the performance of hybrid GNSS and LTE positioning in representative urban environments. This assessment considers field GNSS observables and simulated LTE time-of-arrival (ToA) measurements. The evaluation results show the need to enhance hybrid positioning solutions within future cellular standards.