**5. Discussion**

Considering what has been discussed in previous sections, it is valuable to note that the combination of autonomous vehicles and BRT public transport systems would bring many benefits. The mere application of driverless vehicles would guarantee every citizen the ability to move freely in the city, reducing the number of vehicles by at least 80%. The potential success of this strategy is based on the concept of vehicle sharing by users, which must be promoted and facilitated mainly from an economic point of view, and subsequently, with intermodal platform implementation. It is well known that automation is not a new concept in metropolitan public transport operation. Therefore, their application to potential BRT systems with autonomous vehicles would not require lengthy delays, considering that globally, in 2016, there were already 37 cities with automated metro systems [25]. Furthermore, it is estimated that the spread of autonomous vehicles will occur quickly, facilitated by existing automation systems and technological innovations. Nowadays, the same thing cannot be assumed for BRT systems. This situation can be thoroughly explained with a comparison between case studies in Istanbul and Cairo. In Cairo, the BRT system was proposed as a solution to redevelop the inner city that was characterized by a high population density of at least 21,700 persons/sq.km, thus heavily inclined to congestion. It also aimed to provide an efficient connection with growing

communities settled in the periphery. BRT was regarded as an additional solution achievable in three years and with low costs. However, the project was not realized due to a lack of user trust in the bus sector and skepticism regarding the placement of reserved lanes in an area subject to congestion. In Istanbul, due to a demographic increase of 38.3% and a high number of private vehicles in circulation (4.17 million private vehicles registered), there was a serious problem linked to congestion phenomena. Accordingly, a BRT system was developed by dedicating two lanes of the city's main highway to buses, thus ensuring a considerable daily capacity (30,000 passengers per hour in peak hours) with headways of 20 s. It is important to remark that the first 18.5 km long stretch of the BRT line was implemented in 2007 in just 77 days. Analyzing such cases, considering that both cities are similar in terms of demographics and urban planning, it appears that, while for Cairo the lack of user trust has blocked development, in Istanbul, where the BRT system was implemented in a context of innovation and significantly as a solution to the continuous deferrals of the realization of LRT systems, BRT has achieved excellent results. For these reasons, taking into account that in some communities such as Cairo, BRT was not successful, the application of driverless systems would make it more attractive, especially considering that there are already autonomous vehicles (level 4) capable of operating in mixed traffic. Thus, the BRT system's operational context with reserved lanes and right-of-way would be perfectly suitable [26–30].
