The Kingsway Tramway Subway in London. ...

Hello All, 1 / I often think that the problem with the LCC/LT London Tramways was basically one of generally narrow streets, which was not an insurmountable problem in the 19thC, but became one Post WW1 due to the greater diversity and volume of motor traffic. Buses demonstrated an ability to manoeuvre through narrow roads which trams just could not do. Buses also allowed for greater route variation, and diversions, again something that trams are restricted in doing. Unfortunately, London being a large, and globally known city, London trends were frequently copied overseas. The demand to modernise with buses, partially at the behest of motorist' organisations did not help.
2 / By WW2, the electric Trolleybus was seen as a viable, and cheaper, alternative to trams, and post WW2, with another rapid expansion in lorries/trucks availability, and falling real prices, meant that motor buses, which used a lot of lorry/truck components, became much cheaper than either a trolleybus or a tram, hence the price driven change over to diesel motor buses, whose improving reliability, and easy availability of spare parts made motor bus conversion inevitable.
3 / where trams have survived, especially with shared street running, is usually places with wide roads, eg Amsterdam ( who, by the way, use battery electric buses designed to not exceed tram body width, so that they can use tram tracks on some routes ), or Melbourne. Under these circumstances, where either roads are wide enough, or tram reservations are provided, electric trams are really good for mass movement, especially where passenger numbers do not really justify Rapid Transit / Light Railway provision. The other advantage of trams is that a future upgrade to Light Rail is possible, and this has been demonstrated in what was West Germany in parts of the Ruhr & Rhine valleys.
4 / currently in Melbourne, there is ( slow ) ongoing work to make all tram stops disability compliant with wide platforms and platform/tramcar level entrance/exits. As each of these stops cost around $1m each, and generally loose the ability for cross intersection interchange ( being a particular feature of Melbourne's tram network ), and significantly increase the road width of a tram stop, both local opposition, and tardy implementation is understandable. I personally think the idea of staggered stops ( one on either side of the ) intersections have merit, but they require the use of weaving approach and departure tracks, which cumulatively increase both rail and wheel wear.
Regards to all, Echidna.