When Jim Hacker in Yes Minister asked Sir Humphrey why the M40 (to Oxford) was completed so long before the M11 (to Cambridge), the reply was simple: "It's been years since Transport had a permanent secretary from Cambridge." Ask why the London to Manchester HS2 is so close to the heart of the chancellor of the exchequer while the trans-Pennine "high-speed 3" is a mere pipedream, you need only look at a map. One runs from London to George Osborne's Cheshire constituency; the other runs east from Manchester into here-be-dragons territory and West Yorkshire, where no Tory goes after dark.

Osborne's call this week for the north to get more attention, better civic leadership and new transport links is welcome. He claims we "need a northern powerhouse. Not one city, but a collection of cities – sufficiently close to each other that, combined, they can take on the world." Indeed, the north's lack of economic potency means that "London dominates more and more. And that's not healthy for our economy. It's not good for our country."

Economic geographers have long regarded the greatest brake on Britain's growth to be the stagnation of its provincial cities. Osborne is right to identify leadership as a weakness. It may have improved since the dread days of Liverpool's Derek Hatton, but it remains in the hands of introverted party bosses with none of the public profile or voter legitimacy of London's elected mayor.

Investment is critical. London's overheated economy is the result of the government favouring the south-east with jobs and infrastructure. A recent Institute for Public Policy Research report calculated public and private transport investment in the north-west at £134 a head, but £2,730 in London. Northern cities have been left moribund and bleak compared with their equivalents in Europe. The Don Valley and south Lancashire look wretched alongside the Ruhr or Toulouse.

Whether the answer lies in glamour mega-projects is less certain. Osborne loves them, particularly as his successors will have to find the cash. He doesn't know the meaning of austerity so long as a project is in the south. Show him a London Crossrail, a London Olympics, a London garden bridge or an HS2 to London and his pockets overflow. An empty council flat may appal him, but an empty first-class carriage into Euston is just a quiet ride home.

New railways have become a totem of "caring infrastructure", despite the fact that a mere 3% of journeys in Britain are made by rail. The lines most in need of new capacity are commuter ones. As for the north, there are two trans-Pennine routes from Manchester to Leeds, both in need of upgrading. That it should take an hour and a half to get by train from Liverpool to Leeds and three hours to Hull is absurd.

That doesn't mean a new "high-speed train". The real Pennine lifeline is the M62, and its congested state is a disgrace. It makes even the M1 and M4 look like Silverstone on race day. The A roads along the Aire and Calder valleys are equally desperate. No one can do business when gridlocked. When the transport secretary, Patrick McLoughlin, talks of the west coast line being "near capacity", he should try the north's roads.

Mega-projects have become the quack remedies of modern politics. As soon as one is mooted it attracts lobbyists – and Labour's Lord Adonis – like moths to a light. The Treasury, once a stern judge of such projects, has become their uncritical lapdog. It builds Crossrail 1 rather than the more sensible Crossrail 2; HS2 rather than the more sensible east coast route from the north to HS1; it subsidises trains where coaches are more affordable; and it backs garden cities that increase commuting pressure instead of urban renewal; and it supports two universities in every city where one would do.

A new high-speed railway across the Pennines would apparently cost £7bn, roughly what Osborne wanted to spend getting his HS2 in London from Wormwood Scrubs to St Pancras. The St Pancras part of this link, to HS1, has now been abandoned. This means the government is proposing two high-speed lines, neither of which will run through to the continental high-speed network – transport planning at its daftest.

No railwayman believes HS3 will ever be built. High-speed trains are for countries with long distances and straight tracks between stops. Across the Pennines will always be winding, and the energy cost of stopping and starting high. Spending billions to halve journey times from Manchester to Leeds is poor value for money against upgrading existing track, for which there is already a £600m "northern hub" plan. Meanwhile, Osborne still wants to blow £50bn (probably far more) on HS2 to ease the lot of rush-hour commuters into Euston. Lobbyists, the media and consultants love these adventures in public spending. The headlines are big and the upfront fees huge. The projects are rarely economic and starve more productive investments of cash. It is hard to avoid the judgment that Osborne's "HS3" is for the election, not for real.

Any attention paid to the north is good, but it must be sound. Yes, elected mayors are a good idea, cohering a city round its elected leader and forcing him or her into prominence as its champion. Yes, transport links are essential to prosperity. Yes, there is a role for efficient provincial railways, especially as more people commute between cities. But a bullet train through the Pennines is silly. Equally mad is the idea that somehow five or six cities can congeal into one "powerhouse to rival London". These are intellectual gimmicks of an aloof metropolis. Manchester is the nearest to a "second city in the north" and should be planned as such. But the current revival of Liverpool, Leeds and Sheffield suggests that modern cities can have a distinctive magnetism of their own.

Government helps growth best in not hindering it. Osborne can cut the taxes that cripple urban renewal, such as VAT on building renovation. He can free councils to raise and spend property taxes. He can stop pushing garden cities, rural housing estates and out-of-town hypermarkets, which draw residents and spending power out of cities, jam their roads and wreck their green belts. He can build the right infrastructure, perhaps by giving Leeds and Manchester £3.5bn each, rather than blowing it on a fast train. The best way to befriend a city is to stop being its enemy.