The train only caters for a very limited market, those who live near the Dyce station and work near Union Square. If i lived in Dyce and needed to commute to the central Union Street area then Bain's Coaches is a no brainier, it is slower than the train, however it's far more convenient as it avoids the steep walk from the train station that many people dislike and is "cheap as chips". IIRC an adult fare from Dyce to Union Terrace is only £1.70!
Part of the issue with the train is that Dyce Rail Station is a fair walk from the bulk of the Dyce passenger market. Who'd want to walk 10/15 minutes when you can get a frequent bus at the end of your street. Then that's not to count the fact that many commuters who live in Dyce work up near Holburn Junction and along Albyn Place. Additionally Dyce has quite a number of residents who work in Altens, again the 18 just ends up being more convenient. Again the train is just inconvenient for all of those.
When it comes to a tram route there's so many reason i'd oppose it. So i'm going to make a list of a few...
- There's not enough demand for a high frequency tram service to the Airport.
- The JET727 is fairly direct and provides a frequent 10 minute service with buses through the night.
- There's not enough space in the city centre for Tram infrastructure.
- In order to make a tram service in any way viable it would probably have to take a slower route via places like Heathryfold, Newhills and Stoneywood slowing down the service.
- In the Bucksburn/Woodside areas there's physically no space to "insert" a tram line, so it would have to use Gt Northern Road, which totally defeats the purpose.
Granted the 17/18 can be quite slow now, especially with the 18 going via Danestone. But it wouldn't take much to create a new express version of the Dyce 17 that went direct via Stoneywood Road. Certainly far far cheaper than some pointless train station at Bucksburn and Hayton or a tram line!