3rd Street Trestle Bridge Assessment 2015

City of Austin
.
Founded by Congress, Republic of Texas, 1839
Public Works Department, P.O. Box 1088, Austin, TX 78767-8839
Quality Management Division, 105 Riverside Drive, Suite 100, Austin, TX 78704
MEMORANDUM
TO:
Mr. Howard S. Lazarus, P.E.
Director, Public Works Department
City of Austin
Phone: (512) 974-7190
[email protected]
FROM: Karim Helmi, P.E.
City Structural Engineer - Quality Management Division
Public Works Department
City of Austin
Phone: (512) 974-6539
[email protected]
DATE: August 4, 2015
RE:
Trestle Railroad Bridge, 3rd Street and Shoal Creek Austin, Texas
Mr. Lazarus:
This Memo is in regards to the structural integrity of the existing wooden Trestle Railroad Bridge which spans
over Shoal Creek located at 3rd street downtown in Austin, Texas. See photo A. During our site visit on July
20, 2015, we discussed several future options for revitalizing this section of Shoal Creek which would
incorporate a walkway under the existing wooden bridge. The bridge is deemed to be unsafe, creating
imminent danger to the health, safety and welfare of the public.
During our site visit, it was observed that several vertical and horizontal structural members appear to have
substantial damage by being exposed to the elements. See photos B, C and D. Several of the existing vertical
members are not bearing on the existing concrete foundation. See photo E. At this time, there is no
information regarding the existing concrete structural foundation. I was informed that there had been a fire at
the base of the bridge that was extinguished by the Austin Fire Department (AFD). The fire damaged several
vertical supporting members that were consequently removed by AFD. These vertical members that were
intended to be bearing on a concrete foundation, currently have no positive bearing and are hanging from the
bridge structure above. See photo F. At the time of our site visit, there was a considerable amount of debris
that had been retained by the vertical structural members. See photo G and H. This type of obstruction
imposes a horizontal load on the vertical members which contributes to the unsafe nature of the bridge.
Forensic investigation is required to determine the structural integrity of the existing structural members. This
type of investigation would cost approximately $50,000 and would provide limited information regarding the
current condition of the structural members and possibly information concerning the concrete foundation.
The structural integrity of Trestle Railroad Bridge has been compromised, creating imminent hazard and
danger to the health, safety and welfare of the public. It is my professional recommendation that the bridge be
demolished. If a new bridge is required to be built at this location, it could be designed to fulfill the needs of
the City and incorporate current building codes and standards that have been adopted by the City of Austin. It
is my understanding that this bridge is a historical icon and ties Austin to its past, in which case, certain
members of the existing bridge could be removed and stored. These members could be integrated into the
design of the new bridge for aesthetics. The new bridge design should clear span over Shoal Creek, which will
help eliminate any further obstructions to the creek.
1
Photo A: Existing Wooden Trestle Railroad Bridge
Photo B
2
Photo C
Photo D
3
Photo E
Photo F
4
Photo G
Photo H
5