Abstract: On the basis of principle of marginal cost pricing, the paper discusses the two prevalent standpoints of fine-overloading dilemma and severely-penalty strategy and describes them through microeconomic models. The severely-penalty strategy model has been improved and the impacts of enforcement intensity and marginal penalty on overloading decision of motor carriers are discussed using this improved model. Conclusion is gained that the minimum expectant marginal penalty must be ensured to make overloading enforcement efficient and some restriction factors in enforcement design and implement are also discussed to explain the reasons why repeat penalties at statewide enforcement sites are in vogue actually in China.

Key words: overloading enforcement, marginal penalties, enforcement intensity, fine-overloading dilemma, loading decision

摘要： 运用微观经济学方法，阐述了当前超载治理中存在的“罚-超悖论”和“重罚策略”两种主流观点。运用运输经济学相关理论修正并改进了重罚策略模型，使用该模型分析了超载执法处罚的取缔率与边际处罚对业者装载决策的影响，推导出有效执法的必要条件是保证一定的“最小期望边际处罚”，解释了车辆装载量在执法条件下的微观与宏观变化趋势。通过对超载车辆处罚设计与实际治超过程中一些约束因素的分析，解释了当前普遍依靠多执法点进行重复处罚的原因与该策略可能存在的弊端。

关键词: 超载执法, 边际处罚, 取缔率, 罚-超悖论, 装载决策