It calculates that 300 buses per hour would be needed under GCP plans - but says phase one of light rail could be delivered for £600m.
The government has also announced funding relating to growth around new stations.
There is still uncertainty over the final route.
A new £184million Cambridge South railway station will be built after plans were approved by the Department for Transport.
There had been doubts over the Bedford-Cambridge section.
Campaigners brought a white elephant to the event.
Residents are reminded that a face-to-face meeting with representatives from East West Rail is set to take place today (Wednesday, October 12).
Buses alone ‘not the full answer for city’ says Cllr Lucy Nethsingha.
The PM said that not building these projects fast enough was ‘one of these reasons for our sluggish economic growth’.
Peter Blake’s comments will fuel further speculation over the future of the £5bn scheme.
An embankment dubbed the ‘Great Wall’ could be scrapped after a huge backlash from campaigners, residents and politicians.
Hannah Staunton responds to those who questioned the case for the Oxford-Cambridge line.
A cancelled face-to-face meeting with representatives from East West Rail has been rescheduled to take place next month.
William Harrold questions the value for money, climate change impact and potential of the route.
Infrastructure body delivers verdict on £5bn scheme, while letters show political, business and academic support for line.
The event in Haslingfield on Tuesday (July 19), which was expected to be well attended, has been cancelled.