Patrick Mullings, 15, of Hay Lane school, Kingsbury, north west London, was killed by a train in September 2002.
Patrick, who had severe learning difficulties, was on a trip to attend a routine drama lesson. He wandered off from a group of seven children who were being supervised by three adults and made his way to a railway line.
The inquest in June 2003 returned a verdict of accidental death. An inquiry by Brent council found no negligence on the part of the school.
Gill Reed, Brent National Union of Teachers' health and safety officer, said: "School staff were traumatised by the incident, although exonerated."
Now the Office for Standards in Education has said that health and safety is a strength of the school, which serves pupils aged three to 18 with severe, complex, profound and multiple learning difficulties. Inspectors who visited the 118-pupil school in May said:
"Since a pupil had an accident, the school has developed a comprehensive health and safety policy, drawn up after a very rigorous audit of need and detailed research."
The school said it is to resume outside visits, admitting that the lack of trips had "severely restricted" the range of experiences for its pupils.
The guidelines adopted include:
* Individual risk assessments for each pupil. These are used in addition to a risk assessment for the type of activity and the place being visited.
* an insistence that group leaders are permanent members of staff who have participated in previous visits.
* ensuring that support staff who accompany the pupils have worked with the children for at least a term.