This study is motivated by concerns for the safety of goods and people, as well as the need to provide individuals with the means to prevent and protect against accidental risks and terrorist threats. The research is one of the tasks in the ANR research project \(\mathrm{URB(EX)}^{{3}}\) , which aims at developing a fast-running, breakthrough model for blast consequences in urban configurations. The objective is to characterize the propagation of a shock wave along a straight street using experimental and numerical approaches. The shock wave results from the detonation of a gaseous explosive charge. The experiments are carried out at laboratory scale by applying the laws of similarity. Shock waves are studied using pressure profiles recorded by regularly distributed pressure sensors. Visualization is also used to illustrate various shock wave interactions between the two walls. The explosive charge is placed on the central axis of a street between two parallel walls. The shock wave propagation is analysed in terms of street width and height. It is demonstrated that the shock wave changes its propagation mode from 3D to 2D. It is also shown that several planar shock waves are correlated with the junction of two Mach stems. This study reveals secondary shock waves, as well as multiple shock waves, which can lead to a certain complexity in interpreting the measured pressure signals. The 3D to 2D mode transition zone is determined for each configuration, and an empirical law is established based on the different experimental results obtained. The law considers three parameters, namely the diameter of the explosive charge and the dimensions of the street (height and width).
