Texas Medical Center, Houston, Texas

Scientech was contacted in 2001 by Carter Burgess who was the Program Manger for first Light Rail in Houston from Astrodome to Downtown to fast track the design of a new bridge replacing an existing bridge at heavy traffic Fannin Street over Brays Bayou. This bridge actually was part of another nationally known engineering design firm as part of their overall Segment 1 through Medical Center but was unable to commit to an accelerated and fast track design.

We took the project and were able to cut the original design schedule to less than half and successfully submitted our plans to the selected contractor for early work start. At the onset of project we were given some stringent criteria of trying to use as much of sub structures of the existing bridge as possible including foundations and bents and only consider reinforcing it if necessary. This required the analysis of such structural elements which were designed more than 45 years ago and obviously were not to recent codes load requirements for both vehicular traffic and Rail Loading.

Another reason for this criterion was to minimize the permitting requirements and lengths for new construction in Brays Bayou which is a federally managed steam and is considered as Waters of USA which will require lengthy permitting process. The Hydraulics of the bridge opening (bents and columns) had to stay the same as not to have any new impact on the Bayous.

Additional constraints were presence of an adjacent State health mid rise building with parking garage basements structure so tight against the ROW that the alignment could not be straight and it had to be on a horizontal and smooth vertical alignment to almost half way in the middle of bridge. This geometry posed difficulties both in phasing, elevations and also actual design of the bridge with additional horizontal breaking forces due to curvature.

The bridge consisted of 7 spans, 262 foot long by 97 foot wide concrete structure with prestressed box beams on concrete bents and drilled shafts.  In order to enhance the economy of bridge, almost half of the bridge was designed for roadway loading of HS20 and the rest of affected beams under Rail were designed for Rail loading.  Also to minimize the impact on Brays Bayou the superstructure beams were placed at different elevations with stepped bents to maximize the passage of water under it.