The Royal Welsh Show wants urgent talks with road safety officials after a teenager died following an accident hours before this year's event opened.
Elgan Williams, 16, was a member of the Clwyd Young Farmers Club
Elgan Williams, 16, died on Tuesday after he was hit by a vehicle as he was walking near the showground on Sunday night.
The police also say temporary warning signs had been tampered with.
Show bosses are calling on assembly officials and Powys County Council to review road safety immediately.
Powys Council has installed temporary lighting as an emergency measure as the location.
But Royal Welsh Chief Executive David Walters said: "This unfortunate accident occurred near the Young People's Village which is a popular venue for youngsters, especially in the evenings.
"We are naturally very concerned for the safety and wellbeing of people attending the show, although the society is not responsible for any incidents that may occur outside the perimeter of the showground.
"We will therefore press the county council and the National Assembly Trunk Road Division to examine carefully the safety aspects on all roads surrounding the show site as a matter of urgency, particularly where pedestrian traffic is heavy at certain times."
Elgan, from Groes near Denbigh, was struck as he walked along the A470 between Builth Wells and Newbridge-on-Wye.
His parents, Nan and Bob Williams, have described the death as "an accident waiting to happen".
'Signs were tampered with'
In a statement they said: "Unfortunately it was our son Elgan who lost his life.
"Nothing we do will bring him back, but hopefully the show organisers will see fit to erect railings to save this from happening again."
The incident happened at around 2330 BST on Sunday.
Dyfed-Powys Police have urged the assembly government to consider putting permanent street lighting along the main roads that ring the showground.
Officers have also warned that anyone found tampering with road signs will be prosecuted.
Chief Inspector Peter Westlake said: "Some of the signage has been tampered with and had been ripped down.
"We are replacing it on a daily basis and we have asked for event organisers to make announcements to try to prevent people from taking the signage down."
Lowri Jones, from Welsh Young Farmers Clubs, said that the road remained a concern for their members.
Elgan, who was a member of Clwyd Young Farmers Club, was taken to Nevill Hall Hospital in Abergavenny.