The Valley is being used for research to help plan how supporters can be allowed in stadiums under social-distancing restrictions.
The club has been working with the EFL, Sports Grounds Safety Authority (SGSA), the Government’s stadium safety regulator and crowd dynamics specialists Movement Strategies to model how supporters could return to grounds in a safe and socially-distanced manner.
An EFL statement explained: “The EFL is working with the SGSA on a joint project looking at the impact of applying social distancing to football stadia.
“As a result, work is ongoing at Charlton Athletic and Cambridge United that involves modelling the crowd dynamics of two very different football grounds. This will help us measure the potential impact on stadium capacity and better understand how clubs will need to adjust their matchday operations so that as many fans as possible can be admitted in a safe environment.
“The help and support provided by both clubs has been invaluable and will inform future guidance that will go to all clubs once the Government gives the green light for crowds to return to matches. At this stage we do not know when that will be but we continue to prepare for such an outcome.”