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30 Individuals from five state agencies were interviewed by telephone and e-mail for case examples to identify and collect additional information on bridge demolition practices prior to and during the demolition process. Information collected through the interviews included ⢠Bridge type and extent of demolition; ⢠Information provided to the bidders; ⢠Agency specifications or special provisions at the time; ⢠Requirements (drawings, calculations, procedures, and equipment) for the contractorâs submittals; ⢠Extent of submittal review and reviewer; ⢠Preconstruction or demolition meetings; ⢠Owner oversight of the demolition; and ⢠Lessons learned, suggested practices, or changes made to the process. Five state transportation agencies (Alaska, Illinois, Minnesota, Pennsylvania, and Rhode Island) were selected because of their expressed willingness to provide additional information, type of demolition activities, and geographic location. The information was captured through the state-of-the-practice survey and by direct contact. The survey included additional questions for agencies with bridge demolition project experience, whether successful or not successful, and their willingness to discuss the experience. Case example participants were asked to provide the name of the project, contact information for someone involved with the project, a bridge description and description of the demolition activities, and whether the demolition activities were successfully completed. The information presented in this chapter does not provide a comprehensive summary of the bridge demolition practices of these five state agencies. Rather, these case examples focus on a single bridge demolition project performed by each of the five agencies and highlight key bridge demolition practices implemented in those projects. Due to legal concerns, information and documentation received for projects in which failures occurred were limited. Additionally, some projects may have been older, and not all agencies could locate some of the requested documentation, like demolition submittals or contract documents. Three out of five of the case examples were successful bridge demolition projects, while the others resulted in some type of failure (Table 1). One type of failure was from partial collapse, and the other type of failure was from damaged beams. C H A P T E R 5 Case Examples
Case Examples 31 State Bridge Type Location/ Year Built Demolition Type/Year Special Provisions Demolition Submittal Project Oversight Success of Demolition Alaska 3 spans, steel, cantilevered truss Alaskan Highway, Tok. Year unknown Yes Illinois Yes Yes, sealed by Illinois structural engineer. Illinois DOT Bureau of Bridges and Structures reviewed submittal. Agency and consultant supervised on site. No problems or issues. Minnesota 2 spans, simple, flared, prestressed concrete beams Trunk Highway No. 94, Saint Paul. 1992 Yes Yes, detailed major sequence of operation. Agency reviewed submittal and provided oversight on site. Damage to superstructure led to full superstructure replacement. Pennsylvania US 219 over Elk Creek. 1912 3-stage superstructure removal. 2015 No, standards were used. No, standards were used. Yes, methods and signed by professional engineer. Agency reviewed submittal and provided oversight on site. Demolition resulted in a partial collapse. Rhode Island Along stretch of I-195. Various years Total demolition. 2003 to 2013 Consultant reviewed submittals. Agency supervised on site. Project was a success. Total demolition with blasting. 2011 Total demolition and deck demolition. 2017 Yes, equipment and demolition plans. Deck demolition turned superstructure demolition. 2014 Twin 3 spans, steel, continuous girders with cast-in-place deck and 13 spans, steel, girders, with noncomposite deck 016-1030: I-290 over I-94, Chicago. 1952 016-0461: I-290 over Canal Street, Chicago. 1950 Simple span, CIP Concrete, Inc. rigid frame on concrete abutments 15 bridges, all steel, girder, composite concrete deck bridges Specialty consultants reviewed submittal. Project engineer supervised on site. Yes, included blasting plan. No significant problems. Table 1. Summary of the case examples.
32 Bridge Demolition Practices Case Example 1: Alaska Department of Transportation and Public Facilities Bridge Type and Extent of Demolition Tanana River Bridge was a 946-feet-long, 30-feet-wide, three-span cantilevered truss bridge. The bridge was constructed in 1943â1944 as part of the Alaska Highway. The project was a complete demolition using blasting procedures, and the project was a success (Figure 14). Information Provided to the Bidders All agency documents were made available to the contractor. These included as-built draw- ings, shop drawings, bridge inspection reports (all types of inspections dating back as far as available), and bridge affiliated correspondence. Agency Specifications or Special Provisions at the Time The Alaska Department of Transportation and Public Facilities (Alaska DOT&PF) developed special provisions for the demolition of the truss, including requirements for the contractorâs submittal, removal and disposal instructions, and basis of payment. No parts of the structure could be removed until satisfactory arrangements were made to accommodate traffic, which was relocated onto the nearby new bridge prior to demolition. The bridge demolition plan and blasting plan requirements, as part of the special provisions, are as follows. If explosive bridge demolition is proposed, submit a blasting plan including the following: 1. A list of at least three projects completed within the past 5 years on which the contractor has removed similar bridge structures using explosives. Provide the name and telephone number of a contact person at the agency or company for which the work was completed. 2. A list of the key personnel involved in the explosive bridge demolition. Include information on the superintendent and staff that will be directing and performing the actual demolition operations, including a resume of each demonstrating a minimum of 5 yearsâ experience in explosive demolition. 3. Details of the explosive charges to be used, including manufacturerâs usage instructions and recommendations. Source: Courtesy of Alaska DOT&PF. Figure 14. Tanana River Bridge demolition.
Case Examples 33 4. Detailed plans showing how the structure will be prepared for demolition. 5. Placement of charges and sequence of charge detonation. 6. Methods to contain flying debris. 7. Methods to prevent the structure and falling debris from entering the Tanana River. 8. Provisions for transporting, securing, and using explosives. On-site storage of explosives for explosive bridge demolition will not be permitted. Requirements for the Contractorâs Submittals The contractor was required to submit a bridge demolition plan prepared by a professional engineer registered in the State of Alaska. Plan submittal was required no less than 60 days prior to commencing bridge removal. Included in the demolition plan submittal were ⢠Proposed bridge removal date; ⢠Contact names and phone numbers for individuals responsible for the demolition; ⢠Design calculations demonstrating the integrity of the undemolished portions that would remain after each stage of removal; ⢠Schematic and detailed drawings identifying the method and sequence of removal; ⢠Schematic and detailed drawings identifying and detailing means of access to the bridge during demolition; ⢠Methods to prevent debris from entering the Tanana River; ⢠List of the type, number, and size of all proposed equipment to be used; ⢠Details of temporary support shoring and bracing, if required; ⢠Blasting plan; ⢠Schematic drawings specifying crane locations and lifting locations; and ⢠Waste and disposal control. The blasting plan that was required as part of the demolition plan was to include previous projects the contractor completed, contacts involved with the demolition, details of the explo- sives, their locations on the structure, methods to capture debris, and so forth. Only personnel approved by the engineer could work on the explosive bridge demolition. Extent of Submittal Review and Reviewer Alaska DOT&PF used a specialty consultant and an independent demolition expert to review the submittal. Preconstruction/Demolition Meetings There were approximately six preconstruction/demolition meetings between Alaska DOT&PF and the contractors for the project. Owner Oversight of Demolition The stateâs project engineer was responsible for all contract compliance issues; however, consultant technical expertise was used for specialty demolition issues. Lessons Learned and Changes Demolition of the Tanana River Bridge was successfully completed in accordance with the demolition plans without incident.
34 Bridge Demolition Practices Case Example 2: Illinois Department of Transportation Bridge Type and Extent of Demolition Structures SN 016-1030 and SN 016-0461 were built in 1952 and 1950, respectively, and are part of the Jane Byrne Intersection (I-290/I-90) in downtown Chicago. Their staged partial demolition was part of the reconstruction and reconfiguration of the interchange. SN 016-1030 along I-290 was a noncomposite deck superstructure and substructure staged demolition of twin three-span, three-lane continuous steel girder superstructures and a simply supported cast-in-place concrete deck and beam superstructure that is 502 feet long (Figure 15). SN 016- 0461 was a twin 1,300-foot-long multispan four-lane steel girder bridge that was rehabilitated with new decks, some new steel girders, and repairing and widening of piers. Deck demolition and some steelwork was accomplished by equipment working atop the structure. Information Provided to the Bidders The plans of the existing structure were provided to the contractor. Links to the bridge ratings were provided but were not used by the demolition designer. Agency Specifications or Special Provisions at the Time Illinois DOTâs Standard Specifications for Road and Bridge Construction (2016) were the applicable construction specifications and were supplemented by project-specific special pro- visions in the contract documents. The special provisions stated that demolition work be done in accordance with Section 501 of the Standard Specifications. The contractor was also required to submit a detailed procedure for removing the existing structures to the agencyâs engineer for approval prior to starting the demolition work, including details and calculations of the temporary shoring and timber matting that was proposed. Some temporary shoring was to remain in place for later phases of construction. The special provisions also stated that traffic underneath the bridge removals must remain open unless the contractor obtained a permit to close lanes temporarily. Source: Courtesy of Collins Engineers, Inc. Figure 15. I-290 phased demolition.
Case Examples 35 SECTION 501. REMOVAL OF EXISTING STRUCTURES 501.05 COMPLETE AND PARTIAL REMOVAL OF STRUCTURES Caution should be taken when the plans require removal of existing structures or portions of existing structures. Reinforced concrete structures may require additional shoring if portions of the super- structure are to be removed. The contractor shall follow the demolition plan, if applicable. Extreme caution should be exercised when blasting to prevent damage to underground utilities or other public and private property. Thoroughly discuss the removal plans with the contractor and supervisor. If materials are to be removed and disposed of away from the site, the work should be done in accordance with Article 202.3 and District policy. Structural steel that is to remain must be protected from jackhammer notches and gouges as well as from concrete saw cuts. This type of damage results in stress concentrations that could result in fatigue cracking or failure of a member. Damage to structural steel can be minimized or eliminated if the contractor places proper emphasis on controlling the deck removal process. The deck removal process should not result in any damage to the structural steel. However, should damage occur, the following guidelines will assist field personnel in assuring that proper corrective action is taken. These guidelines are not to be a convenient method by which the contractor can compensate for negligence in the deck removal process, but rather as a last resort when unavoidable damage has occurred. The contractor will be required to hire a structural engineer to provide repair procedures and details for all damage done during the removal operation. No repair shall be undertaken without the recommenda- tions of the Bureau of Bridges and Structures and the concurrence of the Bureau of Construction. Damage that appears insignificant may be major. Damage to the top flange in the negative moment area (steel in tension) on continuous beams or girders is a major concern. Any gouge, notch or depres- sion greater than 1/16 in. (2 mm) deep shall be subject to review by the Bureau of Bridges and Structures. Typical repair procedures require the gouge to be ground smooth with a minimum slope of 1:3 (V:H). All final striations due to grinding shall be parallel to the longitudinal axis of the beam. To ensure that small microcracks are not generated during the grinding process, extreme pressure cannot be applied to the grinding tool to speed up the grinding operation. After grinding is completed, the area shall be checked with the dye penetrant or magnetic particle testing procedure. The term âsmoothâ is defined as American Standards Institute roughness value 250. Gouges deeper than ¼ in. (10 mm) may require specialized repair such as controlled welding accom- panied by ultrasound testing, bolted flange plates over the gouge, or other procedures deemed necessary to restore the integrity of the structural steel member. Unless there is [a] preexisting condition, the contractor will be responsible for all damage resulting from the deck removal operation and all cost associated with the corrective work required. Determination of whether or not there is a pre-existing condition will require special diligence on the part of the inspector during the deck removal process. Requirements for the Contractorâs Submittal The contractor was required to submit a structure demolition plan for each structure that included a full description of the demolition work procedures, structure calculations, drawings, and pertinent equipment information. The required structural assessment report assessing the structureâs existing structural condition was incorporated into the demolition submittal. An Illinois-licensed structural engineer prepared and sealed the submittal. Extent of Submittal Review and Reviewer Illinois DOTâs Bureau of Bridges and Structures reviewed the demolition submittal for general conformance to contract requirements and structural evaluation only. Some structural calculations may have been prepared by the reviewer to verify portions of the submitted procedure, but exhaustive calculations or analyses were not in the scope of their reviews and were not performed. The contractor and their Illinois-licensed structural engineer were fully responsible for the adequacy and completeness of their evaluation and for the successful completion of the work.
36 Bridge Demolition Practices Preconstruction/Demolition Meetings Construction coordination meetings were held between the contractor and Illinois DOT construction inspection staff. At one of those meetings or at a separate meeting, prior to beginning the work, the demolition plan was discussed and reviewed. Owner Oversight of Demolition Illinois DOT construction staff, assisted by an independent consultant inspection staff, inspected and provided oversight on site to ensure contract compliance. The demolition contractorâs licensed structural engineer was required to verify the adequacy of the temporary shoring tower system after installation, prior to loading. Lessons Learned and Changes Illinois DOT was aware of no problems or issues that caused delays or concerns.
Case Examples 37 Case Example 3: Minnesota Department of Transportation Bridge Type and Extent of Demolition Bridge No. 62881 was a 234-foot simple two-span flared bridge, with 54-inch-deep pre- stressed beams on concrete abutments and piers. The extent of the demolition was a staged complete deck removal and disposal, including the entire concrete deck slab, end diaphragms, concrete barrier, and split median barrier. Several prestressed beam flanges were damaged during the demolition process, and a superstructure replacement had to be conducted thereafter. See Figure 16. Information Provided to the Bidders The bidders were provided access to bridge plans as well as to new bridge plans showing the existing beams. The plan set also contained proposed removal lines of the bridge deck. Agency Specifications or Special Provisions at the Time Agency special provisions relevant to the demolition plan required the contractor to submit a plan documenting the proposed removal equipment, protection methods for property to remain, duration and start time of demolition, equipment position, and progress path with demolition. The special provisions also detail pollution control requirements near roadways, air, land, and Source: Courtesy of Minnesota DOT (MnDOT). Figure 16. Bridge No. 62881.
38 Bridge Demolition Practices water. A formal submittal of a demolition plan was to be submitted well in advance of the actual demolition. An excerpt follows. SB-15.6 Removals for Bridge No. 6288[1] Description of Work This work consists of staged removal and disposal of the specified portions of the superstructure and the specified portions of the substructures of Bridge No. 62881. The work shall be performed in accordance with the applicable provisions of the Mn/DOT 2433, the Plans, as directed by the Engineer, and the following: Removals Removals shall include, but not be limited to, the following: Solid Median barrier and split median barrier modified with concrete slab, as shown in the Plans as Stage 1 Removals, on top of the existing deck of Bridge No. 62881. Specified concrete deck slab, reinforcement, expansion joints and specified prestressed concrete beams and diaphragms. Specified reinforced concrete portions of the substructures. Other concrete that may be deemed by the Engineer as necessary to remove in order to complete the reconstruction work on the bridge. Salvage and reuse of specified prestressed concrete beams is required as shown on the Plans. Special Requirements for Removal All removal operations shall be conducted in accordance with the traffic control requirements of the Project and in accordance with the Contract line schedule described in Division S of the Proposal. For specific areas of the bridge, the Contractor shall submit removal plans to the Engineer for approval. The plans, covering detailed major sequences of operations, shall be submitted to the Engineer, at least, thirty (30) calendar days prior to start of removal operations. The plans shall include, but not be limited to a description of and design computations for temporary structures (if used), location of equipment, type of equipment, sequence of removal, sizes of pieces removed, method of hauling, location of hauling equipment, etc. At concrete removal where surfaces will remain exposed on the completed structure, reinforcement shall be ground smooth to the surface and coated with gray epoxy paint. The concrete surface shall also be ground smooth to coincide with the adjacent surface. If the concrete removal extends below the surface, the Contractor shall apply an approved patching compound to restore the surface to the adjacent areas. Removal Operations At the beginning of the work on bridge members that will remain in place, be reused or salvaged, the Contractor shall demonstrate the proposed method of concrete removal in the presence of the Engineer. If the Engineer determines that continued use of the Contractorâs method could result in damage to structural members, i.e., beams and pier cap, that are to be reused, the removal method shall be changed to one that will preclude such damage. In addition, individual workers shall be qualified to do the work and shall be required to use reasonable care, so they do not cause damage to the portions of the bridge that are to remain in place. In no case shall wrecking balls, Whiphammer⢠machines, or other similar devices be used for concrete removal unless authorized by the Engineer. The Engineer may permit the use of up to 60-pound jackhammers by individual operators, provided they demonstrate their ability to operate the hammers without damaging the remaining concrete. No concrete removal shall be performed in any areas until cutlines, if applicable, have been marked by the Engineer. Cutlines that will be exposed on the completed structure shall be sawcut to a minimum depth of one inch. Saw cuts shall be less than one inch at cutlines where the reinforcement designated to remain could be damaged by deeper cuts. Existing reinforcement that is designated to remain in place as shown in the Plans in the finished structure shall not be damaged by removal operations. All reinforcement bars that are to remain in place shall be straightened to original shape, cleaned of all rust and concrete by sandblasting to remove loose rust and mill scale, and cut to length, if necessary for the new construction. Tightly adherent rust and mill scale may remain on the surface. In order to expedite removal operations, the Contractor has the option of cutting the in place reinforce- ment at the cutlines and replacing it with grouted reinforcement or epoxy anchorages as required to
Case Examples 39 maintain the initial strength of the member. At specific cutlines, as noted and detailed in the Plans, additional reinforcement will be required to supplement the in place reinforcement. If no additional reinforcement is required, the replacement bar areas shall be equal to or greater than the aggregate are[a] of the reinforcement bars that were cut. The Contractor shall examine the original bridge plans to determine if there is sufficient area in which to install bar anchorages if the in place reinforcement is cut. Remaining reinforcement displaying deep pitting or loss of more than 20% of cross-sectional area shall be augmented with reinforcement bar anchorages as shown in the Plans, and as directed and approved by the Engineer. Refer to SB-15.8, Grouted Reinforcement Bars[,] for anchorage usage requirements. After removal operations have been completed, the removal areas on which new concrete will be placed or will be exposed on the finished structure shall be cleaned of all remaining loose concrete by sandblasting, spent sand and debris shall be removed by air blasting. Damage due to the Contractorâs operations to portions of the structure that are to remain in place or salvaged, including useable [sic] reinforcement bars, unless removed as described above, shall be repaired to the satisfaction of the Engineer at the Contractorâs expense. All damage to outside of fascia beams designated to remain shall be repaired to original dimensions. All partial depth damage to the top flange of interior beams designated to remain, to be re-used or salvaged shall be repaired if damaged area exceeds 2 square feet. All full depth damage to interior beam top flanges in beams that are designated to remain, to be re-used or salvaged shall be repaired. Contractor to submit repair procedure to Engineer for approval at least 10 days prior to beginning repairs. All material and debris resulting from removal operations shall be disposed of in accordance with the provisions of 2104.3C [of the Standard Specifications for Construction (2014)]. Requirements for the Contractorâs Submittals A detailed major sequence of operations had to be submitted to the Engineer at least thirty calendar days prior to the start of removal operations. Calculations are usually only required for complex or continuous span steel structures. Extent of Submittal Review and Reviewer Minnesota DOT project engineers submit bridge-specific submittals to the respective regional bridge construction engineer (RBCE). There are four regional bridge construction engineers covering the state of Minnesota in regional zones. The RBCE either reviews the submittals directly or enlists the assistance of the engineer of record. In this case, the RBCE reviewed the submittal for equipment, procedures, contingency plans, and preventative measures to avoid property damage from debris and to prevent damage to the structure to be preserved. Review involved thinking of consequences of damage from a depth of design knowledge and construction experience. Comments were returned to the contractor [if necessary] to seek an adequate response, including how the contractor would mitigate any identified risks not previously addressed in the plan. At times, Minnesota DOT restricts demolition practice to sawcutting and slabbing out the deck. However, normal practice is to permit contractors to develop their own plans and mitigation measures provided they adequately address the comments of the reviewing engineer. Preconstruction/Demolition Meetings There were weekly meetings held by the project engineer during construction that included dialogue on demolition. Owner Oversight of Demolition A Minnesota DOT inspector provided oversight during demolition.
40 Bridge Demolition Practices Lessons Learned and Changes In this instance, the agencyâs inspector was on site but the contractorâs engineer who prepared the demolition plan was not present. The demolition took place on a full weekend closure of I-94, a weekend that was one of several windows pre-arranged and identified in the contract as permissible with advance notification and traffic control advertisements. Pre-identified weekend windows are often necessary on projects of the Twin Cities to improve event coordination. The project development team and resident engineer reviewed the allotted closure windows for adequacy in accomplishing the work. However, it is common to have weather-related delays that shift weekend closures to another weekend. These closure shifts can be detrimental to project progress, but the contractor does not incur penalties resulting from weather-related shifts. Minnesota DOT responded with the following lessons learned: ⢠Demolition started at 10 p.m. Friday night, with progress through noon Saturday. Normal demolition can last 2 days. It is rare to see demolition extend into Sunday. At this site, the demolition proceeded too quickly. Although flange girder lines were marked, no effort was made to clear the debris during removals in order to make those lines remain visible. In addition, the foreman failed to direct equipment operators, to control large equipment use, or to adjust equipment in response to damage. The inspector was hesitant to halt work due to the pressures of the weekend traffic closure and instead continued to notify the foreman that the damage was severe, and they should adjust their methods. It is unclear whether any com- munication was given to the equipment operators in response to the foremanâs notifications. These conversations occur in the dark of night operations when the pressure to make progress on the task is high. The lessons from this experience were both with the project engineer and with the inspector. ⢠The project engineer needs to hold pre-activity meetings in which real commitments can be obtained from the contractor on action plans with triggers. For inspectors, Minnesota DOT now reinforces to all bridge inspectors that they have the authority to halt work regardless of traffic closure impacts. Halting work should always be invoked in response to contractors not following their own demolition plans or damage to property to remain that is severe. It is difficult to convey to the non-engineer what âsevereâ means to a structure, because many times there are dings in steel flanges or spalls in concrete flanges that are difficult to avoid. Minnesota DOT now communicates to inspectors that severe damage to prestressed beams means both sides of a prestressed beam flange at any section of the beam or a single side within the middle half of the beam. The rationale is that prestress redistribution may occur and reduce the beam capacity or that patch repairs would not fully participate in the reconstructed beam if repairs are made in peak compressive regions. Severe damage means a replacement of a beam in most circumstances, which represents not only monetary material cost to the contractor but also real construction delays. No time or material compensation is granted in the contract to contractor-caused delays. For steel girder damage, an assessment is made by the RBCE and the engineer of record after damage is reported. Minnesota DOT has started tracking costs for contractor-caused issues to enable recoupment of engineering and related drafting time from the contract.
Case Examples 41 Case Example 4: Pennsylvania Department of Transportation Bridge Type and Extent of Demolition SR 0219 was a 67-foot simple span, cast-in-place concrete ribbed rigid frame bridge on concrete abutments built in 1912, as shown in Figure 17. The extent of the demolition project was a three-stage superstructure removal that resulted in a partial collapse. An adjacent box beam bridge replaced the 1912 bridge. Information Provided to the Bidders The bidders were provided the existing clear span, minimum underclearance, skew, clear roadway width, type of structure, year built, and limits of removal. They were also given available plans. Source: Courtesy of Pennsylvania DOT. Figure 17. Bridge SR 0219.
42 Bridge Demolition Practices Agency Specifications or Special Provisions at the Time At the time of construction, it was Pennsylvania DOTâs specification for bridge demolition, Publication 408/2011 (Change No. 7), which described the contractorâs requirement to submit a demolition plan and removal methods and circumstances for which they needed to have it signed and sealed by a professional engineer. Since this bridge span was less than 80 feet, no professional engineerâs seal was required. The agencyâs special provision described what was required to be included within the demolition plan and described demolition methods that were not permitted. Furthermore, the provision contained requirements on how to remove and dispose of demolished materials and the contractorâs responsibilities to repair or replace any damage that was caused to portions of the bridge that were intended to remain. SECTION 1018 REMOVAL OF EXISTING BRIDGES OR CULVERTS 1018.1 DESCRIPTION This work is the removal and disposal of existing bridges, culverts, or superstructures 1018.2 MATERIAL ⢠TopsoilâSection 802.2 ⢠Seeding and Soils SupplementsâSection 804.2 1018.3 CONSTRUCTION a) General. Submit a plan to the District Executive showing or describing the demolition and removal methods to be used for the removal of an existing bridge or culvert, as indicated. Demolition plan submissions for bridge removal over roadways or with spans exceeding 24,000 mm (80 feet) are to be signed and sealed by a Professional Engineer, registered in the State. Do not proceed with this demolition work until the plan has been reviewed and accepted. Within the plan, provide methods for the protection and safety of the general public and public utilities. If the structure to be removed is over or under a railroad, submit the accepted demolition plan to the railroad companyâs Area Engineer. Do not proceed with the demolition work until written acceptance is received from the railroad company. Provide a copy of this written acceptance to the Department. Notify the railroad company 10 days before starting demolition work. Failure to obtain the railroad companyâs acceptance will require an alternate plan submittal to the Department and the railroad company for review and acceptance. After removing the existing structure, backfill the area where the existing bridge or culvert was removed, as specified in Section 202.3(f). Grade into the existing topography. If directed, place topsoil. Seed and provide soil supplements, as specified in Section 804.3. Use a type and rate of seeding and soil supplements typical for project. Mulch with the type and rate of mulch typical for project, as specified in Section 805.3. Where the removal area coincides with new construction, backfill voids below the elevation of the bottom of the proposed footings, using acceptable material, then compact, as specified in Section 202.3(f). If indicated, leave in place portions of the existing substructure that do not interfere with new con- struction, landscaping, or other operations. Provide documentation (photographs, survey notes) for portions of the structure to remain in place if blasting is used as method of removal. b) Structures Retained by the Department. If indicated, remove members or parts of the structure to be retained by the Department. Match-mark the members or parts and place them within the right of way at an indicated or directed location, within 300 m (1,000 feet) of the existing structure. If indicated, load the members or parts, haul them to, and unload them at, the indicated location. If indicated, load the members or parts on railroad cars, ready for shipment. c) Structures Retained by the Contractor. If not otherwise indicated, the Department will not retain structures, or parts of structures. Remove and dispose of the structure, or parts of the structure, in a satisfactory manner. Requirements for the Contractorâs Submittals The contractorâs submittal must describe the demolition and removal methods and must be signed by a professional engineer, registered in the State of Pennsylvania, if the bridge span is
Case Examples 43 greater than 80 feet. Within the submittal, the contractor must provide methods for the protection and safety of the general public and public utilities, equipment to be used, debris containment system to be used, and a schedule of operations to be presented at a preconstruction meeting. Extent of Submittal Review and Reviewer For this project, the districtâs structural control engineer reviewed and accepted the demolition plan from the contractor. Preconstruction/Demolition Meetings Pennsylvania DOT did not conduct any preconstruction or specific demolition meetings for this project. Owner Oversight of Demolition The supervisor for transportation construction inspection was Pennsylvania DOTâs inspector in charge during the demolition of this bridge. The consultant also had an inspector on site. Lessons Learned and Changes Pennsylvania DOT updated their standards to include additional information the contractor needs to provide within the demolition submittal plan, including ⢠Methods of protection and safety for the general public, inspection personnel, and construction personnel. ⢠Location and method of protection of utilities. ⢠Phasing and sequence of operations indicating construction equipment to be used for the intent of the operation being performed. ⢠Location and weights of equipment during demolition. ⢠Weights of equipment/materials to be staged/stockpiled on the structure. Consider the con- dition of the existing structure when proposing to place loads on the portion of the structure to be demolished. ⢠When and how critical sections of the structure are to be removed (i.e., fracture critical components, arches, or rigid frames) and provide analysis as required to determine the structural stability of partial or complete parts of the structure being demolished. ⢠Method of providing temporary support for elements that will become unstable. In addition, the type of bridge that will require a professional engineer to sign and stamp the bridge demolition plan increased from just one criterion to seven criteria. The bridge must meet just one of the following to require a professional engineerâs stamp and seal: ⢠Over a roadway; ⢠Span length exceeds 80 feet; ⢠Existing structures without plans with span length over 50 feet; ⢠Arches or rigid frame structures with span length over 50 feet; ⢠Fracture critical structures; ⢠Structures on, under, or adjacent to a railroad; or ⢠Specifically called for in the contract. Pennsylvania DOT also included a requirement for predemolition meetings between the representative, structure control engineer, contractorâs superintendent, and the person responsible for the development of the demolition plan.
44 Bridge Demolition Practices Case Example 5: Rhode Island Department of Transportation Bridge Type and Extent of Demolition Beginning in 2003 and ending in 2013 there were 15 bridges demolished to make way for the I-195 Relocation Project. The bridges involved were steel girder bridges composite with concrete decks, both single span and multispan bridges. There were no continuous bridges. Information Provided to the Bidders Rhode Island DOTâs specifications and plans of the existing structures were provided to the bidders. Agency Specifications or Special Provisions at the Time The Specifications for Road and Bridge Construction (Rhode Island Department of Transporta- tion 2013) standards for the removal of existing bridges (Section 803) detailed construction methods for the process of salvaging materials, disposing of materials, restoring disturbed areas, and instructing the contractor that portions of the structure that are to be removed must be removed in a way that will not damage the portions of the structure that are to remain. Structures to be reused must be matchmarked and not damaged. The agency details the type of pneumatic hammer, chipping hammer, or chipping tool restrictions as well as cleaning instruc- tions, prior to the placing of new concrete. Requirements for the Contractorâs Submittals Contract special provisions supplemented the standard specifications and required the contractor to submit demolition qualifications meeting certain criteria consisting of equipment to be used and demolition plans. The demolition plans were required to include drawings, calculations, and procedures. Extent of Submittal Review and Reviewer For this project, a consultant reviewed the submittals, including general conformance to the standard specifications and special provisions. The submittals were also sent to Rhode Island DOT for review and comment, and for concurrence. Preconstruction/Demolition Meetings Biweekly meetings on construction issues were held. It is not known whether the meetings included demolition subjects. Owner Oversight of Demolition The stateâs resident engineer supervised construction demolition for Rhode Island.
Case Examples 45 Lessons Learned and Changes The bridge demolition was completed as planned, and no changes to demolition procedures were made. Stability computations for the bridges based on the demolition methods used were reviewed and approved and that process will be continued in the future. Summary The five case examples illustrate a variety of project types for bridge demolition and methods. Included were total bridge demolitions, partial demolitions, and phased demolitions. Three of the agencies reported successful project completion, while two of the agencies reported the occurrence of unintended events. All agencies required demolition submittals, though to varying degrees of detail. Most of the agencies required equipment information and work procedures as part of the demolition submittal; however, only Alaska and Illinois required calculations as part of the submittal. Special provisions for the projects were developed to augment state standard specifications. All the agencies had various people with different levels of experience providing oversight. Alaska, Rhode Island, and Illinois all had outside agency inspectors, while Minnesota had just an agency inspector, and Pennsylvania had both an agency and consultant inspector. Demolition meetings were not common among any of the case examples; however, demolition topics were broached in some pre-construction and recurring construction meetings.
