About half of all traffic slowdowns are caused by temporary traffic flow disruptions. These are the unwelcome surprises that take over part of the roadway, such as an accident blocking a lane, a construction zone causing a bottleneck, or inclement weather conditions that affect all drivers. These are the slowdowns that you typically can’t anticipate.

The other half of slowdowns are caused by recurring congestion. Many drivers experience these delays multiple times a week. They are more predictable as they occur whenever too many vehicles enter the roadway, such as during a specific time of day (e.g., rush hour, which is likely on the way to work, after work, or weekends).

Even though we know when they’re likely to occur, many of us can’t avoid getting stuck in these delays, simply because our schedules are similar to those of the other drivers on the road.

Temporary measures free up road capacity that is soon filled by induced demand: people adapt their lifestyles to prevailing road conditions. Such measures are therefore worth pursuing only if they either buy time or lay the foundations for more radical interventions. We take a quick look at measures in this category that should not be considered as solutions – at least not in isolation.

Virtuous measures start a feedback loop that induces more and more people to make a modal shift away from driving. Making a bus service more convenient or cheaper will increase patronage, which means that the service can be run more frequently and for longer hours, making it convenient and attractive to more people. These are the changes transport policy must support.

Modern, sophisticated initiatives that are better than typical ‘big ideas’ include:

As can be seen, these begin with interventions requiring only a low level of capital investment, before moving on to those which require an increasing degree of public and/or private sector investment. We will look at each in turn, before finishing by looking at the role of transport in health and welfare and providing some concluding thoughts.

It is often incorrectly suggested that congestion may be solved with one big idea, such as:

None of these can deliver a complete solution, and most of them provide only temporary relief until induced demand fills up the road space once more. Road pricing (which we cover later) is the nearest to a one-hit solution, but it still needs to be paired with big improvements to public and active transport options.

如果物种产生寿命短的后代，他们需要产生很多数量除非它们可以扩散到新的栖息地。很多植物靠风传播大量体积小并且短命的后代。另一种策略则是植物产生更少但更大并且更长命的种子通过动物来传播。

发芽的适应性在colonizing species 发展的很好。 特定物种种子发芽日期让他们更有可能在合适的环境下发芽。这对于气候多样性环境中定居的物种来说尤其重要。