| 1 | A | B | C |
| --- | --- | --- | --- |
| 2 | ex post versus ex ante length of life for engineering construction, 1985 to 2010 |  |  |
| 3 |  | expected length of life |  |
| 4 |  | ex post | ex ante |
| 5 |  | years |  |
| 6 | asset description and code |  |  |
| 7 | highways, roads, streets, including: logging road, signs, guardrail, lighting, etc | 22.1 | 28.7 |
| 8 | rail track and roadbeds including: signals and interlockers | 39.9 | 26.5 |
| 9 | telephone and cablevision lines, underground and marine cables | 19.4 | 16.2 |
| 10 | communication towers, antennae, earth stations | 27.0 | 20.1 |
| 11 | gas mains and services | 43.0 | 42.3 |
| 12 | bulk storage | 24.9 | 26.4 |
| 13 | mean, all assets | 29.4 | 25.3 |

Question: how many years are the ex post estimates for the long-lived assets?
Answer: 29.4

Question: how many years are the ex ante estimates for the long-lived assets?
Answer: 25.3