Table 2.5.2.6.3-1 of AASHTO LRFD Bridge Design Specification 8th Edition recommends minimum depths for reinforced concrete t-beams of \(0.070L\) for simple spans or \(0.065L\) for continuous spans.
Clause 2.4.1 of WSDOT Bridge Design Manual recommends a span/depth ratio of \(13\) for simple spans or \(15\) for continuous spans.