The aim of this Diploma Thesis is the identification of the critical factors affecting travel time in Athens, during the pilot implementation of the Athens Great Walk (June – October 2020). For this purpose, travel time data was recorded in specific road sections via GoogleMapsAPI. The traffic volume of vehicles and pedestrians along with the modal split were collected through field measurements for the period examined and the final database was completed with the geometric features of the road sections examined. Five statistical models of linear regression and lognormal regression were developed in order to capture the correlation between travel time and the factors affecting it on Panepistimiou street and in each category of road axes considered. The results revealed that the factors affecting travel time in the center of Athens are significantly related to the traffic of passenger cars, taxis, buses and trucks, with eco friendly modes of transport such as walking and cycling as well as road infrastructure which includes the number of traffic lanes and bus lanes. In conclusion, on Panepistimiou street, the cross sectional road increase from three to four lanes that took place in the second phase of the pilot implementation of the Great Walk of Athens, led to travel time increase.