Spa is home to a funicular lift. From what I have been able to find out, this appears to be Belgium's only funicular.
The funicular climbs the valley side from the town up to the spa.
Although there are two cars, they function independently of one another.
The car on the right (as you look downhill) is for general public use.
Notice how the gradient changes near the top of the funicular.
The car on the left is exclusively for guests staying at the Radisson Blu Palace Hotel, taking them straight from the hotel to the spa.
Many two-car funiculars operate with one car counterbalancing the other, but this is not so at Spa. Each lift operates on demand.
With a population of a little over 10,000, Spa's public transport services are not surprisingly less extensive than in larger cities. Nevertheless, the town is on the Belgian rail network, at the end of a branch line.
Trains generally run hourly serving two stations, Spa and Spa-Géronstère. While Spa station has a booking office, Spa-Géronstère, at the end of the branch line, is unstaffed.
Trains run hourly down the valley from Spa to the nearby towns of Verviers and Welkenraedt, providing interchange with onward services to Eupen, Liège, Brussels and beyond as well as across the border to the German city of Aachen.
Several bus routes serve Spa, although some services only run on schooldays. Services frequencies on the two main routes are generally one bus every 1-2 hours, with services running daily. A town service operates three times a day, with no service on Sundays.
When I paid a brief visit to Spa on a Saturday afternoon, I found a couple of standard single-deck vehicles in operation.
The buses are provided by TEC (website in French only).