坦桑尼亞的桑給巴爾市因發展旅遊業，導致瀕危的桑吉巴紅疣猴棲息地減少及變得破碎，平均每兩至三星期便有一隻紅疣猴被車撞死。為減少意外發生，當地在主要出沒馬路加設減速路拱，成功把意外率下降到六星期一宗。當地計劃再加設更多路拱來把意外率減至更低。

habitat for the endangered Zanzibar red colobus is fragmented and continues to shrink because of tourism growth in Zanzibar, Tanzania. in average, a red colobus is killed every 2-3 weeks because of vehicle collisions. To reduce the number of collisions, speed bumps were installed in roads the red colobus frequently cross. with the speed bumps, it helps to reduce the number to 1 collision in 6 weeks. Officials are planning to install more speed bumps in the future to further reduce the risk of collision.