Campaigners have raised concerns that a section of the forthcoming Oxford to Cambridge rail line may require a costly tunnel to protect the Mullard Radio Astronomy Observatory near Cambridge. The East West Rail (EWR) project, supported by Chancellor Rachel Reeves, aims to create a direct rail connection between the two university cities, with a targeted completion date in the mid to late 2030s. The new line is expected to cut journey times to just over 90 minutes.

Cambridge University, which operates the observatory located near the village of Harlton, has formally objected to the proposed route. The university highlighted that the planned railway would pass within 150 meters of the observatory’s boundary and approximately 800 meters from its core facilities, which include ten sensitive radio and optical telescopes. Established in 1957, the observatory is known for its vibration-sensitive instruments and has been associated with two Nobel Prizes in physics, notably for the discovery of pulsars.

The university expressed support for the railway in principle but stressed serious concerns about the proximity to its scientific equipment. Its statement noted that the telescopes detect very weak signals vulnerable to disruption from light pollution, electromagnetic interference, and mechanical vibrations caused by nearby infrastructure—including trains. Such interference could compromise or invalidate prolonged research measurements, potentially threatening ongoing funding which may total up to £3 million annually.

In response, Cambridge University urged that mitigation strategies be implemented before endorsing the railway’s advancement. Its proposals included rerouting the line, constructing tunnels to shield the observatory, or employing specialized traction systems designed to minimize electromagnetic emissions.

Campaign group Cambridge Approaches also objected to the current proposals, citing information from an East West Rail engineer regarding a possible solution—a Faraday cage encompassing the railway to block electromagnetic interference. This structure would need to stand about 11 meters high atop an existing embankment of similar height, resulting in a combined 22-meter-high barrier stretching for several hundred meters. The group noted that such a large infrastructure would require separate planning approval and compared its scale and potential controversy to the HS2 bat tunnel at Sheephouse Wood, a £100 million, 900-meter-long facility designed to protect populations of rare Bechstein’s bats.

Natalie Wheble of the East West Railway Company acknowledged the importance of the observatory’s concerns while emphasizing the project’s benefits. She noted that the university recognized the railway’s potential to enhance connectivity, accelerate academic collaboration, and reduce travel times to key sites by up to 75 percent. Wheble stated that all consultation feedback was being carefully examined as part of a broader review process to incorporate stakeholder input effectively.