Adelaide's geography and the distribution of industry surely suggests that upgrading south road to a north-south expressway ensures you provide the greatest benefit possible? Our relatively low population and density means journeys often cover a large distance (I’m basing this purely on personal experience I should add). Alleviating congestion from arterial routes would ensure they can better serve local communities, which is what they were always intended for.monotonehell wrote:Well reasoned. Let's look at it in the context of Adelaide then shall we?paul wrote:The principle of Induced Demand is not particularly complex and is often at the heart of arguments by those against roads in general. I suspect its impressive sounding name is designed to intimidate opponents and is presented as an indisputable fact. That said, it is used as it does have some merit, however it must be looked at in context - is the growth in traffic a result of economic growth, population growth? the increasing affordability of cars? And, if there was an increase in car usage is this outweighed by the environmental benefits of a nonstop motorway?, the economic benefits of improved transportation?
Should new roads result in a disproportionate increase in car usage during peak hours, road pricing could be introduced during those hours to discourage CBD commuters while maintaining the benefits of a motorway for freight and business traffic and the those making a weekend visit to granny in the northern suburbs.
adam73837 - I admire your persistence!!
During peak periods (the times when people complain that the roads are at or above capacity) which arterial roads are 'full'? The answer is - all of them. Where do those roads go? The answer is - all directions. In light of that, in order to relive congestion where is the best place to run a freeway? Probably in no one corridor. The reason is that people do not go from a common point A to a common point B. Their trips are many and varied.
The main point that comes from the study of induced demand on freeways is that they aren't always the answer, and in most cases are actually a route to a larger problem, as well as negative flow on effects. In a sprawl like Adelaide people want to go in many different directions, therefore it makes more sense to spread the traffic load over as many roads as their are directions. During peak period there are a few common destinations, and a well patronised public transport system can help reduce the load by catering to those people.
That's not to say freeways don't play a positive role in a city. Just that the patterns of use don't always turn out to be what people envision them to be. We've had around 50 years of experience to learn from in the rest of the World. No need to repeat their mistakes because we don't ask the right questions.
The freeway, as a means of moving a vehicle from point A to point B in the most efficient manner is as relevant today as it was in the 1950s. What has changed is the balance has shifted from a grossly disproportionate emphasis on freeways at the expense of PT, a complete absence of any consideration of the aesthetics and location of a freeway in the 1950s and a shift towards inner city living over the last two decades or so.
A well designed and managed expressway should be part of Adelaide’s transport network and could even be complementary to our existing PT network (perhaps dedicated bus lanes during peak hour?)