Gray said: "The decision to cut GARL and 1300 jobs is a savage blow to jobs in the west of Scotland.
The GARL plan was included in the original bid when Glasgow was awarded the 2014 Commonwealth Games But Games organisers have said that the link is not crucial to the success of the event.
He added: "The decision not to reinstate the key GARL
transport project, and all the economic and environmental benefits that would bring, is particularly disappointing.
Liz Cameron, chief executive of the Scottish Chambers of Commerce, said: "In our view, the GARL project could be affordable.
The letter states: "The GARL project is not only desirable but affordable.
Swinney axed GARL last month, saying it would save pounds 175million.
Finance Secretary John Swinney dropped the pounds 200million GARL
scheme - and 1300 jobs - last month.
Half of the pounds 400million GARL
scheme will go ahead.
The link, known as GARL, will be scrapped even though it helped secure the 2014 Commonwealth Games for the city.
Scrapping GARL will save pounds 170million, finance secretary John Swinney said as he outlined his pounds 35billion budget for 2010-11.
In the meantime, the decision to scrap GARL - a key part of Glasgow's winning 2014 Commonwealth Games bid - has been widely condemned.
But projects such as GARL are too important to be used in a game of political brinkmanship.