| Rank | Project | City | Tunnel length | Approximate cost per kilometre (million 2010 USD) |
| 1 | East Side Access | New York (US) | 2km | $4,000 |
| 2 | Second Avenue Subway Phase 1 | New York (US) | 3km | $1,700 |
| 4 | Crossrail | London (GB) | 22km | $1,000 |
| 7 | Central Subway | San Francisco (US) | 2.7km | $500 |
| 8 | Singapore Downtown MRT Line | Singapore (SG) | 42km | $490 |
| 10 | Amsterdam North-South Line | Amsterdam (NL) | 9.5km | $410 |
| 11 | City Rail Link | Auckland (NZ) | 3.4km | $410 |
| 12 | Budapest Metro Line 4 | Budapest (HU) | 7.4km | $360 |
| 13 | Toei Oedo Line | Tokyo (JP) | 40.7km | $350 |
| 14 | Nanakuma Line Extension | Fukuoka (JP) | 1.4km | $320 |
| 20 | Paris Metro Line 14 | Paris (FR) | 9km | $230 |
| 26 | Copenhagen Circle Line | Copenhagen (DK) | 15.5km | $170 |
| 27 | Barcelona L9/10 | Barcelona (ES) | 47.8km | $170 |
| 33 | Naples Metro Line 6 | Naples (IT) | 5km | $130 |
| 34 | Milan Metro Line 5 | Milan (IT) | 5.6km | $110 |
| 39 | Seoul Sin-Bundang Line | Seoul (KR) | 18km | $90 |
| 41 | Helsinki Westmetro | Helsinki (FI) | 13.5km | $70 |
| 42 | Seoul Subway Line 9 | Seoul (KR) | 27km | $40 |
| 43 | Barcelona Sants-La Sagrera Tunnel | Barcelona (ES) | 5.8km | $40
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