The Assembly – and in particular Ieuan Wyn Jones, transport minister and deputy to Rhodri Morgan – will soon be presented with an opportunity to make a mark which will last  a half-century or more.

Alternatively, the institution, its ministers and its civil servants could bust their chances through short-sightedness, inability to plan, and failure to innovate.

The gossip has been heard around Cardiff Bay for about a month. But this week an  apparently well-founded press leak has gone far to turn this gossip into fact.

The railway line between Swansea and Paddington is to be electrified. Current plans are to make an announcement early in the new year, with the intention of starting work in 2012.

According to the magazine Today’s Railways UK, the work would be done in five years – or even in three.

Now, this will of course be a London scheme, bringing nearer to completion long-term talk of electrifying all the main lines from the English capital.

Which only goes to emphasise the London-centredness from which the rest of Britain suffers.

But once the electric wires reach Cardiff, the situation changes dramatically for Wales. For some years, work was under way under the old South Glamorgan County Council to electrify the suburban railway system around Cardiff.

After the county was converted into two unitary authorities, it seems the professional engineering working on the project was quietly disbanded – at least partly because of the disruption which accompanies any such major organisational changes.

The idea at the time was linked to talk of running trams to Cardiff Bay. To this day, the precise routes which these tramlines would follow are carefully safeguarded by planners.

But a decade or more later, the transport situation  in the South has changed somewhat. At that time, one of the reason for trams was to get rid of the ugly Bute Street railway embankment.

Now, traffic is growing so much on the Valleys railways that all the talk is of expansion. Platforms are being expanded to take six-car trains; the line to Ebbw Vale has reopened; the next plan surely will be the reopening of the Beddau link at Llantrisant.

Cardiff now is rapidly developing a metro system the equal of the best in the British Isles and the equal of those on the Continent.

A metro system is typified by frequent services (preferably every 15 minutes); stations which are close together; good links to bus services (OK, that’s still to happen in a worthwhile way).

Indeed, trains on a metro take the place of buses on our jam-packed roads.

In Rhondda, almost every village has its station (which means, collecting all the fares is a tough job for the guard !). On the Coryton branch, some stations are within walking distance of each other.

All right, the Ebbw Vale line is a failure from the point of view – a number of the stations closed by Dr Beeching have inexcusably failed to reopen.

All that is obviously wrong with the Valleys system is the trains. Most of the coaches have only two axles; the last time two-axle coaches were common on the valleys, it was the 19th century, and the coaches were swiftly relegated to use on colliers’ work trains.

New trains are needed in the Valleys.

Now, it so happens that one of the main reasons for the Paddington electrification is that the high-speed trains (HSTs) have to be replaced.

The question must then be raised as to whether we get heavy-weight electric trains, as used around London, or whether we adopt systems pioneered some years ago in Germany allowing the new trains to double up as trams and enter town centres (as well as Cardiff Bay…).

This will be a big project. It will mean an enormous amount of work be all levels in the Assembly. Fortunately, the minister is a friend of the railways…

And if we are thinking in coalition terms, this would be a true coalition project.  For the person who first spoke of a Cardiff metro was Sue Essex, the Cardiff North Labour AM, and subsequent transport minister.