Accessory dwelling units (ADUs) are increasingly touted as part of the solution to the intransigent housing shortages facing many metropolitan areas across the United States. But numerous barriers to ADU development persist, including opposition by neighboring households. One persistent question is whether ADU residents would overwhelm on-street parking in the predominately single-family neighborhoods where ADUs are typically built. That question is difficult to answer because there is a surprising dearth of research on the effective parking supply in single-family neighborhoods. We use a survey of homeowners in Sacramento, California, to investigate the supply and sufficiency of residential parking for single-family homes, including how households actually use their garages, and help answer the ADU parking conundrum. After estimating and accounting for actual garage use, we find that more than 75% of households have enough off-street parking available to park all their vehicles. When we combine off-street and on-street parking supplies, we find that households have an average of 1.6 more parking spaces available to them than they have vehicles. That parking surplus is more than enough to accommodate the average ADU tenant and their vehicle, belying claims that ADUs will overwhelm existing parking supplies in single-family neighborhoods.

中文翻译：

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你说停车位不够？萨克拉门托单户住宅的车库使用和停车供应研究及其对 ADU 的影响

附属住宅单元 (ADU) 越来越多地被吹捧为解决美国许多大都市地区面临的顽固住房短缺问题的一部分。但 ADU 发展的诸多障碍依然存在，包括邻近家庭的反对。一个持续存在的问题是，ADU 居民是否会在通常建造 ADU 的以单户住宅为主的社区中压倒路边停车位。这个问题很难回答，因为对单户社区有效停车供应的研究令人惊讶地缺乏。我们使用加利福尼亚州萨克拉门托的房主调查来调查单户住宅的住宅停车位的供应和充足性，包括家庭实际使用车库的方式，并帮助解答 ADU 停车难题。在估算和考虑实际车库使用情况后，我们发现超过 75% 的家庭有足够的路边停车位来停放所有车辆。当我们将路外和路内停车供应结合起来时，我们发现家庭的可用停车位平均比他们拥有的车辆多 1.6 个。停车位盈余足以容纳普通 ADU 租户及其车辆，这与 ADU 将压倒单户社区现有停车位供应的说法背道而驰。