Querying the half-finished bridges

Thanks to Kobus Van Zyl for this question: "Just what are the main reasons for the half-finished bridges we see in CT? Also, the M5 to Muizenberg stops abruptly in a connection that was clearly designed for the highway to continue." Why?

Good question - any suggestions?

Here's my (much abridged) version. 

The plans for the M5 and M3 came rather late in the overall road planning for Cape Town's roads and as early as 1955 the National Transport Commission was warning that heavy expenditure was anticipated in Cape Town and future road proposals would need to be "scientifically studied on the basis of a traffic survey" (City Engineer's Report 1956). Not surprisingly, then, Cape Town commissioned a large traffic survey in 1956.  A ten-year road plan was developed in 1957 but even this did not contain the M3 or M5 and the first plan of them that I am aware of is in 1960 (by which time the N2 and N9 were substantially open and operational - construction on the Black River Parkway between N1 and N2 began in 1961.)

The Foreshore material makes clear the growing tensions between levels of government over road funding during the 1960s, and this must be understood in the context of pressure for more road expenditure across urban areas throughout the country. All this in a time when South African engineers were emboldened to follow their US cousins and propose dense networks of  freeways and expressways. The plan right (from Road International magazine) from 1965 shows one version of the freeway plan. 

By the 1970s the political, financial and planning pressure (together with some citizen pressure from Newlands) had become too much and local municipalities simply ran out of money and appetite for what were (in retrospect) probably over ambitious freeway plans. M3 and M5 were rather low down the list and so were effectively suspended (along with elements of the Foreshore Freeway).That's my take on it anyway. Anyone else?