Zürich: Hohlstrasse

As part of a broader plan to increase the capacity and reliability of trolleybus line 31, Zurich implemented a center-running, alternate-direction transit lane (B4) on a 400 m-long section of Hohlstrasse in 2019. Buses can use the lane in both directions, with special roadside transit signals controlling access. The lane is marked only by paint, so buses can exit it quickly if needed. At the eastern end near Hardplatz, inbound buses transition into a lateral lane via a dedicated phase, while eastbound buses use a dedicated center-running lane beneath the Hardbrücke.

At the western end, westbound buses share the last segment with left-turning cars. However, the signal is metered to clear the left-turn when the bus reaches the shared lane, then provides a bus-only phase so buses can move to the curb after the intersection, where the stop is located. Lateral streets are managed with simple yields and right-in/right-out (L3) configurations. The typical line 31 headway is 7.5 minutes (8 buses per hour per direction).