Transcript Slide 1
The Historic Bridge Project Development Process Session Goals •Brief Review of Historic Bridge Inventory Results •Discuss procedures for Select and Non-Select bridges •Provide tips for preparing an alternatives analysis Definitions • Select Bridges • historic • most suitable for preservation • excellent examples of a given type of historic bridge • Non-Select Bridges • historic • not suitable candidates for preservation • not considered excellent examples Results of Historic Bridge Inventory Volume 4 - List of Select and Non-Select Bridges http://www.in.gov/indot/2743.htm Results of Historic Bridge Inventory 5,313 Bridges Analyzed: 796 4,517 Results of Historic Bridge Inventory 796 Historic Bridges: 86 275 435 Results of Historic Bridge Inventory 435 Select Bridges: 35 400 Non-Select Bridges Early Project Development Process Tips: • Bridge Marketing—Should at least be concurrent with early coordination letter • Historic property report still needed • Archaeology report still needed • INDOT review of alternatives analysis Non-Select Bridges Alternatives Analysis • Rehabilitation for Continued Vehicular Use • One or two-way roadway on historic bridge • One-way pair: historic bridge & new bridge each carry traffic • Bypass (non-vehicular use) • Relocate (non-vehicular use) • Replacement Non-Select Alternatives Analysis Reasons to dismiss an alternative: • Minimum design standards cannot be met or mitigated • Minimum design standards of railroad cannot be met Non-Select Alternatives Analysis Reasons to dismiss an alternative: • Initial rehabilitation cost ≥ 40% of replacement cost • Bridge meets any two of the following: • Waterway opening is inadequate • Documented history of catching debris due to inadequate freeboard or due to piers in the stream. • Requires special inspection procedures • Classified as scour-critical • Fatigue-prone welded details are expected to reach end of service lives within next 20 years. • Sufficiency Rating of lower than 35. Non-Select Alternatives Analysis Reasons to dismiss an alternative: No one steps forward to claim bridge. • Bypass (non-vehicular use) • Relocate (non-vehicular use) Non-Select Alternatives Analysis Be SPECIFIC when describing deficiencies! PROVE your argument. Inadequate information: The bridge deck is too narrow. Specific information: The existing bridge has a clear roadway width of 30.0 ft. The current design criteria for US 33 requires a clear roadway width on the bridge of 42.0 ft. Non-Select Alternatives Analysis More examples: The bridge does not have enough vertical clearance. The existing minimal vertical clearance is 14 feet 10 inches. According to the Indiana Design Manual, the preferred minimum vertical clearance is 16 feet 6 inches. Non-Select Alternatives Analysis More examples: The bridge piers provide inadequate clearance for the railroad tracks. The existing horizontal clearance for the railroad tracks beneath the bridge is 18’-2”, which is substandard because the required clearance is 25’. How can you improve these statements? • The bridge’s sufficiency rating is really low. • The bridge’s load rating is not high enough for modern traffic. • The bridge is too narrow for farm equipment to cross. Non-Select Alternatives Analysis Tables can help summarize info: Non-Select Alternatives Analysis Summary paragraphs are helpful: As outlined above, Alternative No. 3 addresses the purpose and need of the project, through the replacement of existing bridge with a new bridge on the current alignment. The existing bridge cannot be feasibly maintained or rehabilitated to the current design standards or modern loadings. No one has stepped forward to take ownership of the bridge. Therefore, preservation at another location can be dismissed. The best solution is to demolish the existing structure and construct a new bridge in accordance with the current INDOT and AASHTO standards. After comparing all alternatives, Alternate No. 3 is the recommended course of action for this project due to the sufficiency of this alternative. Non-Select Alternatives Analysis Ballpark cost estimates might suffice when: • Design issues clearly dismiss alternatives • Difference between rehab and replacement option is clearly disparate Non-Select Alternatives Analysis Detailed cost estimates might be needed if: • Project is controversial • Consulting party challenges analysis • Difference between rehab and replacement is very close to prudency cut-off % Select Alternatives Analysis • Select Bridges must be preserved as part of the project • Select Bridge owner is responsible for preservation Select Alternatives Analysis Design exceptions might be needed Higher threshold for dismissing rehabilitation: • Initial rehabilitation cost ≥ 80% of replacement cost Coordination for Rehabilitation • Secretary of the Interior’s Standards for Rehabilitation • Plans to SHPO for review: • 30% • 60% • Final Secretary of the Interior’s Standards for Rehabilitation http://www.nps.gov/history/hps/tps/standards/reh abilitation.htm • • • • Repair Replace in kind Replicate historic features Reversible changes Coordination for Rehabilitation • EXPLAIN work to be done • Consulting parties are not engineers • Consider a consulting party meeting Coordination for Rehabilitation Be SPECIFIC when describing/justifying changes Example: The existing bridge railing openings are 9”. The proposed railing openings are 6”, which is the maximum opening allowed by AASHTO standards. Coordination for Rehabilitation More examples: Given that the current turn-outs are not original, are a non-integral part of the bridge that do not greatly contribute to the engineering significance, and often pose a scour issue, it was decided that replicating them in some form is not a prudent and feasible option. Coordination for Rehabilitation More examples: The existing railing does not include chamfering. The proposed railing includes a ¾” chamfer. This addition is because INDOT generally requires chamfering to allow easier removal of the concrete formwork after pouring and to keep the corners from breaking off. Coordination for Rehabilitation Color-code plans if needed: Coordination for Rehabilitation Color-code photos if needed: How can you improve these statements? • The bridge will be widened in the rehabilitation. • The existing railing will be removed and cannot be reinstalled, so Railing Type TX will be used instead. • The decorative brackets under the sidewalk will be replicated to almost match the originals. Late Project Development Process Tips Public hearing: • Required for EVERY Select and Non-Select bridge • 6-month marketing period must be over • INDOT has initialed the CE for release for public review and comment Late Project Development Process Tips CE approval: • No separate 4(f) document needed • Historic Bridge PA stipulations not implemented included in Project Commitments Database Questions Documents available on INDOT website: http://www.in.gov/indot/2743.htm INDOT Mary Kennedy (317) 232-5215 [email protected] Patrick Carpenter (317) 233-2061 [email protected] FHWA Larry Heil (317) 226-7480 [email protected] Michelle Allen (317) 226-7344 [email protected]