Driverless Passenger Shuttles are operating as a public transport alternative in the town of Sion, Switzerland since June'16, and traversing the populated commercial and residential zones of the city center. The absence of a human driver and the lack of dedicated AV-pedestrian interface makes it challenging for road users (pedestrians, cyclists, etc.) to understand the intent or operational state of the vehicle and negotiate road usage. In this article, we present a co-design study aimed at informing the design of interactive communication means between pedestrians and autonomous vehicles (AVs). Conducted in two stages with the local community --which is accustomed to the AV's ecosystem and has interacted with it on a daily basis-- the study highlights the interactive experiences of road users, and furnishes contextualized design guidelines to bridge the communication with the pedestrians.