New-type　urbanization　necessitates　smart,　green,　and　efficient　logistics　systems　to　meet　growing　mobility　demand.　This　paper　explores　the　road-underground　co-modality　for　urban　freight　transport　(RUM4UFT)　as　a　solution　to　urban　traffic　challenges,　which　includes　three　modal　split　strategies:　mixed-use　metro　lines,　metro　freight-passenger　integration,　and　purpose-built　underground　corridors.　A　monetized　cost-benefit　analysis　(CBA)　model　is　developed　to　evaluate　the　major　costs　of　RUM4UFT　and　the　accompanied　benefits　in　transportation,　ecological,　and　logistics　economics　from　the　perspectives　of　the　public　sectors　and　logistics　service　providers.　Taking　the　Beijing　Municipal　Administrative　Center　as　a　case　study,　the　CBA　model　demonstrates　the　advantages　of　RUM4UFT　in　promoting　social　and　environmental　sustainability,　with　the　purpose-built　underground　corridor　offering　the　highest　long-term　investment　value.　The　findings　provide　valuable　insights　for　advancing　city　logistics　performance　through　underground　transport　initiatives.　©　2024　Elsevier　Ltd