四阶段模型对精明增长模拟的探讨

Exploration of Smart Growth Modeling by the 4-Step Models

同交通有关的精明增长措施集中体现在减少小汽车出行、鼓励非机动车出行、混合土地使用以及大力发展公共交通等方面。传统的四阶段模型主要用于宏观的长期交通预测,在模拟精明增长策略方面存在许多缺陷。为了解决这个问题,必须从三个层次上进行改进:短期内,维持现有的宏观模型框架不变,对其内部涉及的假设、变量和模拟过程进行改进;中期通过微观分析得到同精明增长有关的4D弹性系数对传统交通模型结果进行调整;从长远考虑,应构建对精明增长敏感的同土地利用相结合的新交通模型。交通数据来源和模型方法研究是制约模型改进进程的主要因素。传统的四阶段模型在模拟精明增长方面有许多问题,应当进行全面的改进,但是必须循序渐进,逐步完善。

The transportation-related smart growth strategy includes such measures as reduction of vehicle travel, encouragement of non-motorized travel, mixed land use, promotion of public transportation, among others. The conventional four-step model has primarily been used in making macro-level long-range transportation forecasts, yet suffers, however, several deficiencies in simulating smart growth measures. To address this issue, the paper suggests making improvements on three levels： 1） over the short term, leave the existing macro-level model framework as is, while modifying its input assumptions, variables, and modeling procedures; 2） over the intermediate term, post-process conventional modeling outputs based on the 4D elasticity coefficient derived from micro-level analysis of smart growth measures; 3） over the long term, build a new transportation model, which is sensitive to smart growth measures and integrated with land use. Transportation data availability and model methodology research will constrain the progress of these improvements, however. It is concluded that the four-step model should be considerably revamped due to many existing issues, and that the improvement process should be undertaken in an incremental and orderly way.