JIM STEER

With the Scottish Executive saying that, in the long term, it wants to examine options for reducing journey times between Edinburgh and Glasgow, including looking at new infrastructure and a high-speed railway, the time has come to be clear about what purpose and wider aims would be served.

And since, from 2010, the two cities will be back to the position of being linked by no fewer than four railway routes, why would there be a need for a fifth, however fast?

The answer is that all of the four existing routes carry commuters from intermediate places into the two cities. In doing so, they preclude frequent and fast non-stop running of express trains over what are, in each case, conventional double-track railways. So the fastest time in today's timetable is 50 minutes via Falkirk or 55 minutes via Carstairs, with several stops en route. The fastest train is managing an average of less than 60mph, so step change systems such as Maglev would really have no difficulty in working their magic in bringing travel times between the city centres down to 10-15 minutes. But would the expense and impact of a new system be worth while?

The key, of course, is in the nature of the demand pattern between the two cities, and the way in which economic activities are expected to develop. Business-to-business travel would, of course, be much aided by a dramatic shortening of journey times between the two city centres, which could then truly function as a single economic entity. But the volume of this kind of journey is modest, probably about 200 people/hour in each direction through the day, nowhere near enough to justify substantial investment. It might increase, of course, with a fast connection, but not by an order of magnitude.

A fast link between the two city centres, however, would serve much more than this one travel market, provided there were really good "hub" interchanges in the city centres. Perhaps Haymarket, with the tram, can fulfil this role in Edinburgh, but Glasgow is a tougher proposition, with its rail networks split between Central and Queen Street. Somehow, the fast inter-city-centre connection needs to be recognised as a transformational feature of the central belt's public transport network, the means by which added value can be provided to services, and a catalyst for enhancements to exiting services, in both great cities. This way the spread of benefit will increase and the prospect of living in one city and working in the other, without adding to the congestion and carbon impact created by increasing car travel, can become a reality. Reduced dependence on the car, going into the century ahead, is a valuable prize for any economy.

So the first point is: look at fast inter-city connections on a network basis. As a stand-alone, the case is going to be weak. The ability to boost the use of existing and planned public transport (bus, tram, underground and suburban rail), however, is a key benefit that can be sensibly quantified in a project appraisal.

The new science in geographic studies allows us to go further and to compute the economic advantage of bringing the two cities together in a functional sense. The so-called agglomeration benefits would be very substantial. These arise from the simple fact that, with much easier journeys, businesses are able to take advantage of the proximity of other businesses for trading activity, of having more customers within easy reach and of the ability to access a wider labour catchment.

But what would a new link look like, and what could be done in the interim? How would it relate to a north-south high-speed link from central Scotland to London in three hours, as called for by Tavish Scott at a recent conference, as a complement to a fast link between Edinburgh and Glasgow in 30 minutes?

If the Minister's half-an-hour prescription is to be followed for Edinburgh-Glasgow, this will be a high-speed train, capable of a speed of 125-150mph, able to operate on a route clear of stopping services. But it doesn't need to be a new technology system (such as Maglev). It would mean that systems such as the French TGV technology that are capable of high speed (300km/h+) and operation over conventional tracks where needed - for instance, to access terminals - could be used. Besides a fast journey time, users could look forward to high levels of reliability and safety that flow from the use of a segregated right-of-way.

None of the existing routes is suitable for upgrade to high-speed as they stand because of the intensity of service that needs to continue to be provided to intermediate places. Best placed in practice may well be the longest route, that via Carstairs, where intermediate demand is least and where there is scope to increase line speed and, with targeted investment, remove low-speed sections and pinch-points. This route might support an hourly fast service extended cross-border and offer a journey time of, say, 45 minutes non-stop. This could be a useful interim measure, helping to build the end-to-end rail demand base and to prompt the economic reconfiguration that is the real justification for this type of investment. Residents and businesses could start to make the transition in planning and behaviour on the key location decisions (home-work-school) that a genuine twin-cities geography permits.

There can be no escape from the need to think this through in economic activity terms. If the Glasgow-Edinburgh city collaboration is for real, then there will need to be broadly-based plans for the changes to employment patterns and for the additional growth that could be triggered. High-speed rail can be part of these plans but it would be a risky investment to use it as the driver of closer collaboration. Better to use high-speed rail to provide the capacity that may be needed and to offer efficiency and quality-of-life advantages.

A 30-minute journey time means new tracks. These would possibly be built alongside an existing railway, or the M8, so that environmental impacts are minimised - a lesson learned with the planning of the Channel tunnel rail link through Kent - at least for a central section where high speeds are needed, and probably for much of the route into city centres, too, at lower operating speeds, so that existing rail network capacity is not compromised.

A critical question will be Edinburgh Airport, the one key point between the two cities that might merit its own high-speed rail service. However, if the route becomes a series of A to B to C sections, with intermediate stops, inevitably the end-to-end journey time gets extended. Meanwhile, the time savings available for the shorter sections (eg, from Edinburgh Airport to Edinburgh) are minimal against the alternatives that will be on offer. It might be better to leave Edinburgh Airport to the revised services being planned over the adjoining rail network than try to integrate it into the Glasgow-Edinburgh high-speed concept directly.

Services could be extended beyond the Edinburgh-Glasgow core, however, and Glasgow Airport and other western destinations are one possibility. And however radical this may all seem, remember that in the 1970s you could fly between the two cities, on Loganair's service to Northern Ireland.