Van Hool Double Articulated Bus

This was the first time I'd ever seen a double articulated bus so of course I had to know more. Here's the skinny on this interesting piece of engineering.

The Van Hool Exqui.City 24 Electric uses double articulation to achieve a massive 150-passenger capacity without the cost of laying tram tracks. Its maneuverability is powered by a sophisticated electronic steering system on the rear axles that allows the 24-meter vehicle to navigate tight city corners with the same turning radius as a standard 12-meter bus.

The primary reason for double articulation is Passenger Density. In a Bus Rapid Transit (BRT) system like MalmöExpressen, the goal is "Tram-like" service without adding the massive infrastructure of a real Tram.

In terms of passenger density, this thing is a beast. A standard bus holds ~70 people. A single-articulated bus holds ~100. The double-articulated Exqui.City holds up to 150, nearly doubling the efficiency per driver. Four wide double doors allow for "all-door boarding," minimizing the time spent at each stop.

The "magic" that keeps a 24-meter bus from getting stuck in a roundabout or hitting curbs is its axle and steering geometry. The bus has four axles in total. While a standard bus only steers with the front wheels, the Exqui.City uses a multi-axle steering system. Axles 3 and 4 are actively steered using sensors on the articulation joints to detect the angle of the turn and automatically steers the rear wheels in the opposite direction. This ensures the rear of the bus follows the exact path of the front, a concept called "Path Following Control."

The two articulated joints are also sophisticated, containing hydraulic damping systems and electronic controllers to apply braking in case of severe articulation (aka, jackknifing).

Because of the steered rear axles, the turning radius is only about 12 meters. This means that despite being twice as long, the bus can navigate any Malmö street that a regular city bus can handle.

And it's all electric! Very cool.Read more