Timber Bridge Design , Fabrication and Delivery

2026-11-03

SCOPE OF SERVICES 1 . Geometry : The bridge superstructure is to fit on existing abutments . Plans and survey data for the existing structure are provided as an attachment to this RFP . 2 . Design : The superstructure shall be designed and detailed as a laminated timber slab span utilizing longitudinal spike laminated panels . Glued laminated panels will not be allowed . Deck width shall be comprised of multiple panels interconnected with shiplap joints and supplemented with transverse spreader beams bolted underneath the longitudinal panels . Spreader beam size , spacing , and bolt spacing shall follow AASHTO guidelines . Design of the superstructure shall be in accordance with the following criteria : a . Unless otherwise specified , all dead loads , applied loads and live loads shall be as specified in the AASHTO LRFD Bridge Design Specifications . b . Dead load shall include a 2 ” nominal crowned HMA wearing surface installed over the top of the deck panels and additional 2 ” future HMA wearing surface . The HMA application rate shall average 357 lbs ./ syd . with a minimum 1 . 3 % cross slope for drainage . c . Live loads shall be HL - 93 Modified as designated in the Michigan Bridge Design Manual 7 . 01 . 04A . d . Bridge deflection requirements shall be in accordance with AASHTO LRFD Bridge Design Specifications . e . Individual element dimensions shall be determined by the manufacturer . Timber railing system shall attach to longitudinal deck panel system . Railing system shall be crash - tested to Test Level 3 ( TL - 3 ) in accordance with the current version of the AASHTO Manual for Assessing Safety Hardware ( MASH ). Connection of rail components must be to the longitudinal deck panels only . No connection of rail components to the substructure will be permitted . The design , design calculations , and certification must be signed and sealed by a Licensed Professional Engineer registered in the State of Michigan ...

MITN

2026-04-29