"Such an experience makes one stand back and review life," he said.
His retirement follows Franklin + Andrews' merger with engineer Mott MacDonald.
A spokesperson said that after the merger, Franklin + Andrews had switched from a partnership to a limited company, so it no longer needed a chairman.
Bishop will not be replaced but managing director Guy Leonard will take the lead role in the firm.
Bishop started in the construction industry in 1964 as a management trainee.
In 1985 Franklin + Andrews merged with Bishop Ledger, the QS he co-founded in 1975.
He was made managing partner of Franklin + Andrews in 1990 and appointed chairman in 1997.
Bishop was also heavily involved in the merger with Mott MacDonald.