The current nearest timed bus stop is Leckwith Retail Park - its 13 minutes to Wood St opposite central station by Cardiff Bus Number 95. Ninian park Station to Central is 4 minutes
But the rail service is only every 30 minutes, and you are unlikely to get more than every 30 minutes with whatever heavy rail system you implement on that stretch of line. There's no reason why a tram service can't have traffic priority and should take less time than a bus.
You need to appreciate how people use public transport in an urban city centre. They'll use the bus or tram etc. if it's turn up and go in preference to a train that runs twice an hour. In any event - it's a 20 minute walk from Ninian Park station to Cardiff Central. It's not far.
People at Fairwater, Waungron etc. can virtually depend on the current train service turning up bang on time - that would surely not be the case if it has to get into the city centre via the road network. They also have the benefit of being able to catch one train that almost encircles the more central suburbs. (A teacher living near Heath Halt, for example, can easily get to work at Cantonian High School in Fairwater on one reliable train - avoiding all traffic jams). What this line needs is at least a 15 minute service - something that could perhaps *come if a half hourly service went on a new line out to Cregiau via the new suburbs. * Danescourt excepted - unless the Radyr service was increased.
One problem with the present system is that people can’t make short hops without having to pay the full fare to the city. There is also no system where they can switch to a bus from the train without having to pay again. People can’t even buy a through ticket from a City Line station to Swansea by train without paying about £2 more than if they buy split tickets at Central. This does nothing to encourage travel into Central by the local rail network.
I don't think you'll get 15 minute services terminating at Radyr from Coryton in your hypothetical teacher case. You can't turn around the trains quickly enough on the single-track Coryton branch to deliver this. So he'd only ever have a 30 minute heavy rail service. Maybe, just maybe, the teacher currently has a choice of getting in 25 minutes before he needs to or 5 minutes late. If he had a more frequent service, even if his journey was slightly longer, he may be able to get to his destination at the time he wants to.
Some win, some lose in any reorganisation of a city / regions public transport. Not everyone can be a winner.
A fair point about integrated ticketing.
Del1977 - you seem to be one of the few people in this cave with a torch...! Most are missing the bigger long term picture enabled by LR and are coming to a short term view based on mainly incorrect assumptions...... like I said (and I know some don't like it) lets wait and see.
I think a lot of people are wedded to heavy rail to fix today's problem rather than seeing the potential of light rail/tram trains. There have been some valid objections / points made about the potential drawbacks, but some are more dubious.
I'd sub-divide the objections raised so far as follows:
Trivial:
Toilets on trains.
Comfort of replacement units (interiors can be specified) and ultimately still run on metal rails.
Unsubstantiated:
Trams/tram trains would be 'banned' from Cardiff Central or other parts of the heavy rail network. If it were unprecedented for tram/trains to use heavy rail networks - then fine. But it isn't.
LR will have less seats (no, depends on the seating plans / frequencies).
Valid objections:
Turfing everyone out at Cardiff Queen Street from the MTA lines and forcing a change to reach Cardiff Central.
Breaking the cross-city link to Barry Island from Cardiff Queen Street and beyond.
On-street running for *longer* distance services increasing overall journey times.