大都市由于拥有许多有效的公共运输途径,如地铁,交通情况应该好得多。但在糟糕的现实生活中,汽车的无计划使用和庞大的郊区线路已使解决塞车最天才的努力归于失败。一些出色的主意从未成功,至少未能取得它们应该取得的效果。许多大胆的计划理论上可行,但实现不了。分级网络目录服务是这种现象的又一个例证。 Metropolitan Thanks to many effective public transport routes, such as the MTR, the traffic situation should be much better. But in the worst of real life, the unplanned use of cars and the vast suburban routes have failed to resolve the most talented traffic jam. Some brilliant ideas never succeeded, at least not what they should have achieved. Many bold plans are theoretically feasible, but can not be realized. Hierarchical network directory service is another example of this phenomenon.