Earlier this month, CABE chief executive we visited three US cities to see what Britain could learn from American planning and urban development. His trip diary reveals why both countries cast an envious eye on the other, and unearths the secrets of New Urbanism, Bush-whacking and the planning authority run the Carlsberg way
San Francisco
Thursday 30 October
I start at the Urban Land Institute conference in San Francisco. It's four years since I was last in the city, and the first impression is how little has changed. But it quickly becomes clear that the downturn in property development in the USA, particularly on the West Coast, has had a severe impact.

My evening with the International Council of the ULI throws up an interesting picture. There is no lack of capital for property projects. The conference is awash with major investors looking for havens for their money but there is a shortage of worthwhile projects. It is also clear that 9/11 and the Patriot Act [Providing Appropriate Tools to Intercept and Obstruct Terrorism] have had a much more profound effect on the US real estate sector than I had previously understood. In particular, levels of Middle Eastern investment in property projects have plummeted by being re-directed to Dubai and the Emirates.

I run a session for the council on urban development in the UK. The Barker Review and possible liberalisation of the planning system generates most interest. Americans have little knowledge of the British development scene outside London, although the council genuinely appreciates the Manchester regeneration story. Other projects that stir debate are King's Cross, East London and Edinburgh Riverside.

In the evening, I have dinner with a couple of the guys from British Land, among the few people from the UK at the conference. In terms of content, the ULI "fall" meeting is light years ahead of MIPIM, the nearest European equivalent. The networking opportunities are not as immediate, but the UK development community would find the ULI rewarding. Representation from Japan, South-east Asia and Australia is much higher, and not just because of the Pacific location.

Friday 31 October
I start the day in a design session on town-centre regeneration. One of the strengths of the ULI is its focus on design quality, which makes me regret that we have no equivalent forum back home.

It quickly becomes clear that Hope Six, the Clinton public subsidy scheme for reviving affordable housing areas, has sustained the US development industry in the recent hard times. Some of the mixed-use schemes that have resulted, based on the traditional urban grid and block design with public housing limited to 25-30%, are impressive and seem sustainable.

The session also makes clear how dominant "new urbanist" thinking and culture has become in American Urban Design. I already knew about the close links between the Urban Land Institute and the Congress of New Urbanism, but this appears to have created a conservative orthodoxy.

Looking at the schemes, this seems to have both a positive and negative impact. The urban design is generally excellent, with a strong sense of continuity and enclosure, reasonable levels of density, clear mixed-use neighbourhood centres and a strong sense of community. More disturbing is the architectural repetition. As a rule, strict design codes are imposed on architects' schemes, leading to an insistence on dreary traditional vernacular even down to the material and colour palettes. The overall effect is not terrible, but there is an impression of whimsical nostalgia, of the desire of the boomer generation to return to a 1960s world of soda pops and a night at the hop. On the other hand, if I had a choice between a new urbanist development and the average UK housebuilder offering, I'd not only go to the much publicised Seaside development in Florida, I'd buy the rock.

Next, I am on the panel for a session on traffic congestion charging. Just eight people turn up. Very few people over here are interested in the concept and it doesn't surprise me. To persuade Americans to pay to use roads that are already there, and paid for out of state taxes when there is virtually no public transport seems an impossible sell. I'd lay a bet at twenty to one on a charge for mid-Manhattan in the next decade, but wouldn't touch the rest of the country.

Saturday 1 November
A ULI session on San Francisco shows just how badly the recession has hit the West Coast. Class A offices are 20% vacant, rents are way down to 1997 levels, unemployment is up and the general feeling is that the economy has yet to bottom out. Virtually nobody is building anything other than residential condominiums. Service jobs are being lost in substantial numbers, with significant out-sourcing to the Indian sub-continent and Asia-Pacific. Private developers feel that the municipal authority in San Francisco is living in cloud cuckoo land, delaying recovery by zoning key sites for industrial uses that will never return to a services-based city.

Despite this depressing picture, a session on the revitalisation of neighbourhood retail leaves me brimming with ideas. One of my concerns at CABE is that although the UK's top 70 retail locations are seeing design-led regeneration, most of the secondary and tertiary locations are still in decline. CABE needs to think more from the retail tenant perspective and will have to work closely with the British Council of Shopping Centres and the British Retail Federation to make progress.

Washington DC
Monday 3 November
I wake up in Washington DC and head straight into a meeting with the federal Housing and Urban Development Department. HUD is one of a number of federal agencies we meet that have been "Bush-whacked", with large cuts in their programme budgets to divert resources into the war effort, homeland security and servicing the burgeoning national debt. I get the feeling that much of the best practice they are promoting actually harks back to the Clinton administration.

The good news is that our own Neighbourhood Renewal Unit is significantly ahead of HUD in its distribution of funding. The relative weakness of national institutions within the federal structure means that, until recently, the department did little more than dole out money in block grants in accordance with a needs-based formula. Only very recently has there been any collection of output data, and outcome-based evaluation is only just on the radar. In other words, the federal government is spending billions on urban programmes with little or no idea of their impact.

In the afternoon, we hit the road with the Washington city planners. In sharp contrast to the West Coast, Washington is economically robust, and prospering from the increased presence of federal defence and security agencies.

The New York Planning Commission is fascinated by the fact that CABE’s advice is recognised as a material planning consideration

At the end of the tour, and backed up by later discussions with city developers, architects and NGOs, I can only conclude that if a certain Danish brewer ran a planning authority, it would be like the District of Columbia's. Proactive in enabling development, leading expansion through masterplans, passionate about the public realm and design literate, it is certainly a contrast with the stultified town planning we have in the UK.

I need to understand the difference and reach a few tentative conclusions. The first is leadership from the top. As in New York, Washington's mayor is passionate about planning and architecture as facilitators of economic growth. Accordingly, he has built his planning team from scratch, mixing professional disciplines and backgrounds. The second is that the American "as of right" system of planning approvals, which gives developers free rein and liberates city planners from the day-to-day grind of detailed development control. The planners would like more control, but it has to be said that limiting their intervention to zoning decisions on urban design, massing, density and height means that they can focus on getting the fundamental strategic decisions right.

Tuesday 4 November
We make early tracks to the General Services Agency, which procures all federal buildings on behalf of other state departments, including courts, border buildings and offices. CABE is well aware, and envious, of the GSA design excellence programme, led by its chief architect Ed Feiner. Although procurement has slowed down somewhat since the heights of the late 1990s, it's good to find that the commitment to design excellence remains intact.

The real challenge for the GSA is how to control its expenditure, and how to integrate design and construction programmes. The average cost overrun on its projects is more than 20%, and it fears a design backlash against its use of high-profile architects unless it gets a grip. It would like to embrace PPP schemes, but Congress is resistant. In view of this, the strategy is to dispose of surplus assets and concentrate limited resources on upgrading the rest of the stock. There is no new direct workplace development; instead, federal agencies take leases in private developments. It's all evidence of a tightening of the purse strings by the Bush administration.

Flying to New York, we are hosted in the evening by the American Architectural League, and some of the cream of the US architectural establishment turns out on a misty night in Park Avenue. With senior city officials also present, its difficult to believe such a gathering would take place in most UK cities. It is also a reminder of the deference afforded to the architectural profession in New York. On the whole, I think I prefer our more sanguine approach. Critical scrutiny in the likes of the New York Times elevates the idea of architecture as a privately commissioned object, flowing from the sharper distinction in the US between public and private realm. As a result, there seems to be much less scrutiny of what happens when large buildings hit the ground, with landscaping appearing as an afterthought to satisfy a zoning agreement, rather than the planned context in which the building sits.

New York City
Wednesday 5 November
Fuelled by coffee and bagels, we start the day in Central Park with the New York City Park Authority. It is an impressive performer and its statistics back up my impression that New York is becoming a much greener city, with more parks and more street trees. It is also engaged in huge reclamation projects in North Queens and Staten Island to create new parks on the scale of London's Royal Parks. Will we get to grips with the public space opportunities of the Thames Gateway with the same level of vision and determination?

What is also striking is the advanced stage of planning for NYC's 2012 Olympic bid, driven by the fact that New York has already been through a competitive process to become the nominated city for the USA. I wonder whether New York has been underestimated as we focus on a power battle between London and Paris.

There is a sobering start to the afternoon with a visit to the World Trade Centre site. Demolition work continues, although metro services will resume later this month. We spend time with the Lower Manhattan Development Corporation, which has grasped that the redevelopment can only be properly considered within a spatial strategy for the whole Lower Manhattan area. It also realises that the future of the area is likely to be a network of mixed-use neighbourhoods, including residential, retail and leisure. In view of this, I wonder how sensible it has been to commit to replace the same amount of office space as in the original World Trade Centre site. Many of the previous occupiers have moved to mid-town and for now, at least, the demand just does not exist.

I am once again struck by our different cultures. The LMDC has not developed any masterplan for its area, beyond a basic zoning concept. Even the massive commitment of federal funds gives the corporation limited leverage over the land owners. In the middle of this, Daniel Libeskind is busy drawing up urban design guidelines for the Ground Zero site. But at present we have little concept of what will be built. The only thing I'm sure of is that whatever is eventually built won't look much like the winning Libeskind design.

At New York City Hall we are greeted by Mayor Bloomberg, clearly enjoying his role as a design champion for the metropolis. He has reconfigured City Hall into an open-plan environment, with his own desk and those of his deputy mayors scattered among the desks. It's as far away from the traditional UK model of local government as one can conceive, and none the worse for it.

The New York Planning Commission, like many of the groups we meet, is fascinated by the CABE design review process, in particular that we can advise on the detail of private sector schemes and have our advice recognised as a material planning consideration. As in Washington, the New York planners have to rely on density bonuses and other zoning concessions to achieve their design aspirations. Otherwise, they can only concentrate on getting the public buildings and spaces right.

I conclude the trip over drinks with Alex Garvin, the planner, writer and commentator who is guiding New York's Olympic bid. We reflect on the cultural differences that underpin UK and US approaches to planning, design and construction. At their root is the American Constitution's focus on individual freedom. The state can rarely fetter the rights of the property owner in favour of the public interest. The building boom of the early 20th century gave New York an explosion of diverse and bold buildings like the Chrysler, Empire State and Grand Central Station. But in more recent years, architecture has tended towards the corporate and bland, with the state left to make the best it can of the spaces in between.

In the UK, development control has avoided some of the horrors of the strip development that has blighted so many American cities. But it has also operated as a dead hand, steering developers towards the safe and mediocre so they can negotiate the system as quickly as possible.