These considerations led to a significant reduction in the extent of the road network connections . All of the previously described measures form the managed crossing strategy , with reuse of the existing bridge and a reduced extent of new road construction being key elements in revising the scope of the project .
These changes reduced the cost estimate from circa £ 4 billion to around £ 2 billion . The strategy was announced by the Scottish government in December 2009 and formed the basis for progressing the project .
The project was divided into three contracts . In view of the large size of the project and the likelihood of attracting international consortia to bid , a contract form based on the FIDIC standard conditions for turnkey project ( FIDIC Silver Book , 1999 ) was adopted .
The competition for the principal contract was undertaken in parallel with the progression of a parliamentary bill . In early 2011 the preferred bidder was announced to be Forth Crossing Bridge Constructors .
In total , the overall Forth Replacement Crossing scheme is 13.7 miles ( 22km ) long , including major motorway upgrades to the north and south of the bridge and also the first ever use in Scotland of variable mandatory speed limits to smooth traffic congestion via an Intelligent Transport System . This also controls dedicated bus lanes within the motorway hard shoulders – another first in Scotland .
The bridge is planned to open for traffic in 2017 .
Figure 2 : Forth Replacement Crossing Contracts Figure 3 : Key project stages
1 / 2017