Yes, many European cities, which tend to be higher density than ours, were largely built before cars were invented, so it is perhaps easier to make the transition in such places, and we will clearly have to invest heavily in public transport. We need to anyway; we just do not have sufficient space to rely on using cars to get into the CBD. My colleague Henrietta Cook recently reported that Melbourne commuters are spending as much as three full days a year stuck in traffic. It's a waste of time and energy and is literally driving people to distraction – making people less happy and healthy, and even contributing to divorce. Here's a take by Michael Leunig: There is no reason we can't make fundamental changes here. Again, we need to – you only have to walk through the city to see it's not working all that well: cars are often gridlocked, despite being given undue access and priority. And that daily 850,000 rush of people in and out of the CBD is set to rise to 1,200,000 within 15 years. Pedestrians already need more space; imagine what things will be like in 10 years if we don't reduce the space given to cars. It can be improved. Here's an artist's impression of what Swanston Street might look like: Of course, that is not totally realistic – we need to keep the trams, and Swanston Street is already a stretch where most cars are not allowed. But it does suggest how much better the city would look, feel and operate were we to fundamentally rebalance the priorities towards pedestrians and cyclists, rather than cars.

Today's instalment of The (Ideas) Zone presents a range of solutions and views from experts. Those experts and I will be online throughout today to blog with you; just post your comments and questions at the end of this piece and we'll respond. The (Ideas) Zone is an online space for you – a space for the community to discuss ways to improve our city and our state. By the way, here's a postcard showing what Swanston Street looked like in the early 1900s, before cars had taken over the city: Fast forward to this year's Easter Friday, one the very few days on which you find almost no car traffic in the CBD. We had Jesse Marlow, the inaugural winner of the International Street Photographer of the Year Prize in 2011 (London Festival of Photography/Fotoura), shoot in our CBD. Here's how Swanston Street looked with lots of pedestrians: And without many pedestrians: Jesse had a look at Flinders Lane, too. Then we had staff artist Joe Benke create an impression of how Flinders Lane – which, with its galleries and cafes and boutiques, is a prime candidate to be closed to most vehicles - might look without cars. Here's what happens when you combine the work of Jesse and Joe:

And here's how it looks in Lonsdale Street, another prime candidate for change, given its current drabness and car congestion: One of the experts you can communicate here with today is Dr Ben Rossiter, executive officer of Victoria Walks, a research and advocacy organisation seeking to promote, well, walking in cities, suburbs and communities. Here are some of Ben's thoughts: "For decades we have prioritised cars as the preferred mode of transport to and around the city to the detriment of the city's liveability. Many people think that's life in a big city, that roads are for cars, but this is nonsense. The roads were built for moving people and freight well before cars were invented. Walking was and is the primary mode for getting around the CBD." Here's what Swanston Street looks like totally packed with pedestrians - this was the scene back in 1927 when the Duke and Duchess of York popped in:

Ben loves an experiment in Melbourne back in 1985, when the council closed Swanston Street to cars and covered it in grass. Here's how that looked: Ben reckons we should be aiming to make the CBD all-but car-free. Yes, we'd need to leave access for emergency services vehicles and deliveries for businesses, but we could vastly reduce the number of cars. Here are some of Ben's ideas about how to engineer the change: 1. Drop CBD speed limits to 30km/h. We lag behind cities like Edinburgh, Milan, Paris, Gratz and most cities in the Netherlands. London and even New York are doing better than us. 2. Make Elizabeth St a 20km/h shared zone from Victoria St to Flinders St. Give walkers priority over all vehicles, apart from trams. Make it a flat surface from building line to building line. Get rid of the silly fences at tram stops that inhibit mid-block crossings. Walkers and trams get along when they share this way in cities like The Hague so why not here?" 3. Same for all the little streets and lanes - take out the gutters and make them 20km/h shared zones from Spring to Spencer, and make some car-free completely. Open them only for freight at certain times and residents. Stockholm provides some inspiration.

4. Footpaths are highly congested around Southern Cross Station, so take out lanes of traffic and make them wider. The vast numbers of walkers are more important to the health and economy of the city than car drivers. This would also deal with safety problems caused by overcrowding. 5. Re-imagine the streets around Flinders St Station to be a much more friendly gateway to the city, rather than dumping train passengers at the intersection of two arterial roads, with a succession of fences separating the station from Fed Square." Here's a shot of that problem so many of us are aware of: 6. CBD traffic lights mostly prioritise vehicles not moving the greatest number of people, who are on foot. We should get rid of a lot of them and turn some streets into shared spaces. Exhibition Road in London is a great example of how to re-imagine city streets." Here's a video of how that looks:

Another of the experts you can bounce some stuff off today is Bill Chandler, an architect, engineer and town planner who is one of Melbourne's most experienced designers of space. Bill, who now heads up his own consulting company, chaired Victoria State Urban Arts Unit in the 1980s, and in the 1990s was chief planner, urban designer and marketing director for the Melbourne Docklands Development. Here's a thought or two from Bill: 1. Every trip you make will begin and end with walking. Therefore planning, designing and providing for safe and attractive walking conditions is critical for achieving successful cities. 2. People make trade-offs, but perception rather than reality sometimes guides their choice of travel mode – so, for example, they should compare door-door travel time of private car versus public transport for peak hour commutes." Bill also stresses that when people walk they take up far less space than they do when they drive. Here's how he illustrates that point:

The next expert available to chat online with you today is Adam Williams, a director of AECOM and a former government adviser in Victoria who now lives between Melbourne and Rio de Janeiro, where he is leading a team on the design and development of the Rio2016 Olympic Park, a role that includes advising on the transformation of the park post-2016, which will result in 7000 new homes. Adam says: "In any event, Melbourne has a structure that was established 185 years ago, and while it serves the city well and has managed to accommodate changes in mobility and population (both resident and worker) over the years does the current configuration reflect the needs of contemporary Melbourne?" The City of Melbourne clearly does not think so, and has a plan, released last year, to "crate a safe, comfortable and richly engaging urban environment where pedestrians, cyclists and motorcycles are welcomed and supported through world-leading road safety practices." The plan explicitly "encourages walking and cycling, which are considered to be low cost, energy efficient, space saving, non-polluting and sustainable modes of transport". But are cars still being given too much priority in our CBD? Even with thoroughfares dedicated to private vehicles, the place is gridlocked during the morning and afternoon peaks. Before we throw the debate open to you, let's have a quick look at some other solutions. Milan has an innovative one – to reduce smog and increase space, the city administration gives public transport vouchers to commuters who leave their cars at home. This pic is by Flickr user Chris Yunker:

In Helsinki, planners are anticipating rapid population growth by transforming car-dependent suburbs into higher-density, walkable communities, in part by providing shared "mobility-on-demand" services. An app allows citizens to call up a car, bike or taxi or to locate the nearest public transport. Here's an artists impression of a Helsinki street that's been liberated from cars: Copenhagen started introducing CBD pedestrian zones 50 years ago, and car-free zones have since spread, to the extent that half the city's population now bikes to work, almost 10 times the rate in some US and Australian cities. It's not a bad look: Melbourne has made bold moves in the past – in particular by creating the Bourke Street Mall, removing cars from Swanston Street and closing some laneways to cars. Here's Adam Williams again: "Across the city, we are continually seeing the recalibration of the CBD's streets with the development of the tram super stops, expansion of footpaths, and increase in trees, but is it time again for a bolder move?" Here's a bold idea – build a city in which cars are not necessary, because everything can be reached on foot within 15 minutes. That's what is happening in Chengdu in China. Here's an artist's impression: Well, what does Kim Dovey, Professor of Architecture & Urban Design at University of Melbourne reckon? "Cars need to remain part of the mix for central Melbourne but they need to be contained and tranquillised. Central Melbourne should be a pedestrian priority zone rather than a pedestrian only zone.

"The best ways of limiting the damage of cars is to restrict parking, speed and the total space devoted to cars. Cars need to be slow enough and difficult enough that public transport is faster. Tram tracks should be dedicated for trams only. Pedestrian intensity is good for the city but some parts are reaching gridlock at peak times and should be expanded." Venice is not only one of the densest urban spots on the planet, it's car-free. And it's one of the most-loved built environments. Melbourne is not Venice. Or Paris. Or Milan. We do have a rather terrific city, and by eclectically adopting and adapting strategies from elsewhere we can perhaps improve things here even further. What do you think? Do you have ideas to make the CBD work better? Perhaps the status quo is what you want? Please feel welcome to leave you comments and questions below.