The proposed 16.75 km tunnel road linking KR Puram and Hebbal is estimated at Rs 17,780 crore, or Rs 177.8 billion (bn), according to the project report. The Metro Phase 3A Red Line is costed at Rs 25,999 crore, or Rs 259.99 bn, and shows a lower per kilometre outlay. On a per kilometre basis the tunnel road DPR places construction at Rs 1,061 crore, or Rs 10.61 bn per km, while the Metro DPR cites Rs 687 crore, or Rs 6.87 bn per km. The gap makes the tunnel about one point five times costlier per kilometre than the Metro. The Metro Phase 3A package spans 37.80 km from Sarjapur to Hebbal with a DPR cost of Rs 25,999 crore, incorporating 23.524 km of elevated viaduct with 17 stations and 14.28 km underground with ten stations, totalling 27 stations. An earlier cabinet approval had placed the phase at Rs 28,405 crore, or Rs 284.05 bn, with a per kilometre figure of Rs 776.3 crore, or Rs 7.763 bn per km, prompting scrutiny from the Centre. The proposed Veterinary College station was later dropped, reducing scope and cost. The tunnel road DPR sets the project cost at Rs 17,780 crore, or Rs 177.8 bn, and notes a possible cost escalation of up to forty five per cent by completion. If escalation occurs, the DPR projects the per kilometre figure could rise to about Rs 1,538 crore, or Rs 15.38 bn per km. Fare and toll comparisons indicate a maximum Metro fare of Rs 90, whereas the tunnel model anticipates a round trip toll exceeding Rs 600 and restrictions on vehicle categories, signalling a different user profile. Both schemes serve the same corridor linking south east Bengaluru with northern districts but represent distinct approaches: a high capacity mass transit rail system with 27 stations and a tolled vehicular tunnel aimed at motorised traffic. The DPR comparison highlights trade offs in capital intensity, user costs and projected ridership, and underlines why policymakers will need to weigh long term mobility benefits against construction economics.