Wildlife crossing structures (WCS) are widely used to allow for safe animal movement across roads, promoting both human safety and wildlife conservation. These structures are expensive to build and maintain, and therefore cost-effective design is essential. Although there has been much research to date on the factors affecting the usage of WCS by wildlife, no attempt has been made to synthesize these results and assess the current state of knowledge. We conducted a systematic review of the scientific and professional literature to assess the state of empirical evidence on WCS and a meta-analysis to explore the factors that influence their effectiveness. We identified a total of 270 studies that reported empirical results spanning four decades of research. Most studies (161) measured the number of crossing events without monitoring approaches to the structure, thus limiting the ability to assess WCS effectiveness. Only 77 studies measured the proportion of successful crossings to approaches, which was the type of data used for meta-analysis.

Our meta-analysis results show that viaducts are the most effective type of WCS for large mammals. For example, the odds of ungulates crossing through a viaduct are 2.9 times that of an overpass, and 3.6 times that of an underpass. WCS built specifically for wildlife are used significantly more than those built for dual use by humans and wildlife. For large carnivores, the odds of using a dedicated WCS are 15.9 times that of a structure used concurrently by humans. We additionally found that natural materials and round shapes are preferable in the design of effective WCS. Altogether, these results highlight the importance of adopting large-scale monitoring of wildlife crossing structures. More broadly, we conclude that further research focusing on under-studied species and structure characteristics is needed to facilitate cost-effective mitigation efforts that reduce wildlife-vehicle collisions and promote wildlife conservation.

野生动物穿越结构（WCS）被广泛用于允许动物在道路上安全移动，从而促进人类安全和野生动植物保护。这些结构的建造和维护成本很高，因此，具有成本效益的设计至关重要。尽管到目前为止，已经有很多关于影响野生动植物使用WCS的因素的研究，但是还没有尝试合成这些结果并评估当前的知识状态。我们对科学和专业文献进行了系统评价，以评估WCS经验证据的状态，并进行荟萃分析以探讨影响其有效性的因素。我们确定了总共270项研究，这些研究报告了跨越四个十年研究的经验结果。大多数研究（161）在没有监视结构的方法的情况下测量了交叉事件的数量，因此限制了评估WCS有效性的能力。只有77项研究测量了成功通过方法的比例，这是用于荟萃分析的数据类型。

我们的荟萃分析结果表明，对于大型哺乳动物，高架桥是最有效的WCS类型。例如，有蹄类动物穿过高架桥的几率是高架桥的2.9倍，是地下通道的3.6倍。专为野生生物建造的WCS的使用量大大超过了人类和野生生物双重使用的WCS的使用量。对于大型食肉动物，使用专用WCS的几率是人类同时使用的结构的15.9倍。我们还发现，在有效的WCS设计中，天然材料和圆形形状更为可取。总而言之，这些结果凸显了对野生动物穿越结构进行大规模监测的重要性。更广泛地，