## 2 State of the Art
### Case Study Details  
Stari Most (literally \"Old Bridge\") is a reconstructed Ottoman bridge from the 16 th century located in Mostar (Bosnia and Herzegovina). It crosses the Neretva River and connects the two parts of the city. It is defined as an international symbol of reconciliation in Mostar, Bosnia-Herzegovina: in fact this bridge were destroyed in 1993 during the Bosnian war; the rebuilding activities began five years later, and the bridge alongside Stari Grad (Old Town) was re-opened as a United Nations Educational, Scientific and Cultural Organization (UNESCO) heritage site in 2004 [43]. The Stari Most are 4 m wide and 30 m long and it dominates the river from a height of 24 m. At the end of the bridge, there is two fortified tower titled Halebija to the northeast and the Tara tower to the southwest. They are called \"the guardians of the bridge\". The investigated geometry has been defined following the characteristic features and assuming a flow distribution along the two east and west directions. The bridge is illustrated in Figure 2 below. Figure 1: LOS for stairways (volume versus module) in accordance with [PERSON] theory. Figure 2: Images of Stari Most-Mostar in Bosnia-E. (Source: Google Earth). The functional geometrical evaluation of the bridge was based on the definition of areas and ramps and on the comparison of different scenarios, some of which are characterized by the prohibition of transit in some parts or the presence of a single mono-directional way. The investigated bridge has two ramps with an opposite slope. There are similar steps characterized by a slippery coating due to the type of materials and wear of the surface on which you walk. Although small pieces of raised concrete have been added to help reduce the risk, there is always some danger of moving around the bridge at a fast pace, especially when the ramp is coming down. These concrete elements form steps that create a break in gait. At the edges, the paving of the bridge is in pebbles and allows tourists to stop in order to admire the landscape (about 0.50 m for both sides). The central part is paved in stone different from that of the side areas to the ramps and is characterized by a kind of steps. Monitored geometry is particularly difficult to travel for people with reduced mobility or with motor problems like the elderly. The monitored area is configured as adjacent to the road called Kujundziluk, characterized by restaurants and shops, which connects to the urban road called Marsala Tita on East direction while in the West direction to the road called Onescukova characterized also by the small shops up to the double-lane extra-urban road called Bulevar. The analyzed flow was assessed considering the conditions of greater tourist transit during the summer period (seven days were monitored). The evaluated flow is linked to the daily peak hour and all activities located to the bridge are linked to touristic aspects. Different scenarios were implemented not only along the 30 m of bridge length, but considering also an area of about 30 m was evaluated before and after it corresponding to the area characterized by a further reduction of the width of the lane towards both west and east characterized by the continuation of the pedestrian area surrounded by tourist markets and restaurants. Table 5 shows details about the investigated scenarios: in fact, it is, therefore, possible to focus on the simulated areas by considering the different scenarios in order to maintain and evacuate as the flows change. They have been chosen considering possible maintenance activities without the closure to the transit of the bridge and also of possible evacuation in the terrorism event. Each scenario analyzed involved the simulation of the ramps that make up the bridge named W and E corresponding to East and West part.