In 2012, DelDOT partnered with the Federal Highway Administration (FHWA) on an initiative to develop a training program for newly hired bridge engineers at DelDOT, as well as private engineering firms working on DelDOT bridges or interested in working on DelDOT bridges. As part of this initiative, DelDOT and FHWA identified the Bridge Design Manual as being in need of a redevelopment. Much of the information in the current manual has become outdated, and many of the policies or preferences are unclear.
DelDOT tasked AECOM to support the Department in this effort. The purpose of this re-write is to update the document to be consistent with current bridge design standards and to clearly convey DelDOT’s design policies and preferences. The Bridge Design Manual is complete and can be found at the following link: Bridge Design Manual (15 Mb).
The new bridge design manual contains three distinct sections as follows:
- Section 100 – contains information specific to the development of Delaware bridge design projects including the timing and content of documents, reports and submissions commonly required to complete a design project.
- Section 200 – follows the chapters and format of the AASHTO Bridge Design Specifications. This section provides specific DelDOT modifications and interpretation of the AASHTO manual.
- Section 300 – provides typical bridge design details which may be encountered on DelDOT projects. This section is still under development. Details included herein are not standard and must be represented in the contract documents.
The selection of content considered for inclusion in the new bridge design manual was judged on the basis of three tenants or filters that were developed early in the re-write process. To be included in the new manual, technical content, design direction or design policy must adhere to at least one of the three filters. The filters are as follows:
- Define what is Delaware specific – these are items that are unique to Delaware and can control or impact the design such as geography, geologic conditions, hydrology and hydraulic conditions, weather conditions, traffic movements, etc.
- Indicate Delaware Preferences (unless approved by the Bridge Design Engineer) – these items are design approach preferences by DelDOT and are presented here to promote consistency among individual structure designs.
- Define Level of Development for Fair Procurement – this filter is used to identify items/issues necessary to the development of standardized, fair and biddable contract documents.
Content in the new bridge manual was also judged by the frequency of its occurrence, or likely future use, within the state. This is the "90% rule". It was determined that the manual should focus on information relevant to the structure types commonly (i.e. 90%) utilized in the state. Therefore, the new manual provides coverage of standard highway structures and appurtenances. Preferences and polices for unique structures, such as suspension or cable stay bridges, have been intentionally omitted.
The 2015 Bridge Design Manual has been adopted for use on all projects as of November 1, 2015.