Understanding people’s travel behavior is necessary for achieving goals such as increased bicycling and walking, decreased traffic congestion, and adoption of clean-fuel vehicles. To understand underlying motivations, researchers increasingly are adding subjective variables to models of travel behavior. This article presents a systematic review of 158 such studies. Nearly every reviewed article finds subjective variables to be predictive of transport outcomes. However, the 158 reviewed studies include 2864 distinct subjective survey questions. This heterogeneity makes it difficult to reach definitive conclusions about which subjective variables are most important for which transport outcomes. In addition to heterogeneity, challenges of this literature also include an unclear direction of causality and tautological relationships between some subjective variables and behavior. Within the constraints imposed by these challenges, we attempt to evaluate the explanatory power of subjective variables, which subjective variables matter most for which transport choices, and whether the answers to these questions vary between continents. To reduce heterogeneity in future studies, we introduce the Standardized Transport Attitude Measurement Protocol, which identifies a curated set of subjective questions. We have also developed an open-access database of the reviewed studies, including all subjective survey questions and models, with an interactive, searchable interface.

了解人们的出行行为对于实现增加骑自行车和步行、减少交通拥堵以及采用清洁燃料车辆等目标是必要的。为了了解潜在的动机，研究人员越来越多地在旅行行为模型中添加主观变量。本文对 158 项此类研究进行了系统回顾。几乎每一篇评论文章都发现主观变量可以预测交通结果。然而，158 项审查研究包括 2864 个不同的主观调查问题。这种异质性使得很难就哪些主观变量对于哪些交通结果最重要得出明确的结论。除了异质性之外，该文献的挑战还包括一些主观变量和行为之间因果关系方向不明确以及同义反复关系。在这些挑战带来的限制下，我们尝试评估主观变量的解释力，哪些主观变量对哪种交通选择最重要，以及这些问题的答案是否因各大洲而异。为了减少未来研究中的异质性，我们引入了标准化运输态度测量协议，它确定了一组精心设计的主观问题。我们还开发了一个开放获取的审查研究数据库，包括所有主观调查问题和模型，并具有交互式、可搜索的界面。