Some of these costs have already been included in the cost:benefit ratio such as the impact of pollution and greenhouse gases. Moreover there have already been changes made to ensure that the high speed line runs in tunnels through areas where the damage would otherwise be significant. More than 50% of the route to Birmingham will be in tunnels or cuttings and much of the remainder will have barriers to prevent noise pollution. [1] Given the number of tunnels it is wrong to consider the railway one long barrier to wildlife. If it is considered a serious problem then solutions would not be immensely costly – tunnels under the tracks could be constructed for example.  [1] Railway-technology.com, ‘High Speed 2 (HS2) Railway, United Kingdom’,