Bridge Operation And Maintenance Manual

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Bridge Operation And Maintenance Manual

Bridge Operation And Maintenance Manual

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Bridge Operation And Maintenance Manual

Some of these cookies are essential to make our site work and others help us to improve by giving us some insight into how the site is being used. Structures that are part of the road asset are, like trunk road carriageways, managed and maintained by our Operating Companies who are contracted by Transport Scotland on behalf of the Scottish Government. They carry out day-to-day inspection, planned and reactive structural inspections, monitoring, management, maintenance and repairs to trunk road structures in accordance with the Operating Company contracts, the Design Manual for Roads and Bridges and best practice. This section of the RAMP describes the lifecycle plan for trunk road structures. The inventory records held for road structures comply with the requirements set down in BD62: As Built, Operation and Maintenance Records for Highway Structures, and are held within the Structures Management Function of Transport Scotland’s Integrated Roads Information System. Span ?3 meters. The retained fill height must be above 1.5 meters to qualify as a structure. The types of planned inspections, assessments, monitoring and surveys our Operating Companies are required to undertake in accordance with Schedule 7: Part 7 of the Operating Company Contracts are outlined below: A number of Special Inspections are undertaken to provide more detailed information on the condition and structural integrity of specific parts or components of a structure, including those outlined below. Also as part of the Level 2 Scour Assessment Programme to BD97: The Assessment of Scour and Other Hydraulic Actions at Highway Structures, currently under way to structures over and adjacent to watercourses. A comprehensive programme of assessment has been undertaken to ensure structures can safely carry Authorised Weight (AW) vehicles. It can on occasion relate to the stability of a structure that may be subject to ground movement.

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This would be required where there is change in condition, operational load carrying requirements or changes to assessment standards.Routine and cyclic maintenance activities undertaken for structures typically include. The causes of reactive maintenance vary considerably, but typically include vandalism, vehicle impacts, flooding, fire, fly tipping and ongoing deterioration of the structures. The requirements for defect repairs for all categories of defects are described in Section 5.3. Examples include cleaning of bridge deck and abutment drains and expansion joints on bridges, removal of vegetation, checking and tightening holding down bolts to parapets, maintenance of services, and lighting. Work aimed at counteracting these mechanisms and maintaining the public safety and the durability and safe use of structures is referred to as structural maintenance. Structural maintenance includes repairs due to deterioration or damage, and bringing sub-standard and non-standard components up to current standards. Also, strengthening or replacement of structures that are life expired or unsuitable for current usage or those with substandard load carrying capacity or road alignment. Current specific programmes of work include strengthening and replacement of structures, upgrading of vehicle parapets, strengthening of supports, and scour protection to structures. Table B.2 presents some indicative maintenance activities and their typical renewal frequency for trunk road structures. Under EC Directive all Member States are required to accept articulated vehicles and drawbar-trailer combinations with six or more axles weighing up to 44 tonnes on international journeys. This directive came into effect in the UK on the 1 Jan 1999 and was enshrined in Statutory Instrument No. 3224, see Table B.3. This includes 34 bridges (14 sub-standard verges, 17 sub-standard decks, two substandard supports), one culvert and 10 retaining walls.

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Works have been ongoing delivering the bridge strengthening and replacement programme since 2000, indicating the scale of the impact of increasing vehicle and axle loads on the network. The majority of sub-standard bridges are short to medium span structures on the traditional routes. At the present time Transport Scotland’s policy is to operate all of its structures without weight restrictions, subject to review and monitoring in accordance with BD79: Management of Sub-standard Highway Structures to maximise network availability. However, as public safety is paramount, should ongoing deterioration or traffic volumes and flows alter the load carrying capacity of a structure, this will be reviewed in accordance with BD101. If funding for the necessary remedial or upgrading works is not available then in future it may be necessary to impose traffic restrictions or closures to ensure safety and prevent structural collapse. This schedule of works is known as the Structures Workbank. The Operating Companies review all available information (including all inspection reports, monitoring requirements, test results, known strengthening and replacement requirements) and identify: Each scheme in the one-year maintenance programme is scored against the Safety, Functionality, Environment and Sustainability criteria described in Section 6.1. The index is calculated from General and Principal Inspection data (see Section B4), enabling analysis and trending of condition information. Two condition indicators are calculated for each structure, which are defined as: This score provides an overview of the average structure condition. This score provides an indication of the criticality of the structure with regards to the load bearing capacity. Therefore the condition of these particular structures sits outwith the condition scoring reporting. The graph shows that the majority of trunk road structures have an average condition rating of excellent or good (79).

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The SSCI av score for the structures stock is 86. The SSCI crit score for the structures stock is 76. This involves surveying and inspecting structures, undertaking routine repairs, cyclic maintenance and undertaking essential preventative and reactive structural maintenance. Figure B.4 provides a breakdown of the proportion of investment in each of these asset management activities for structures. This will allow us to understand better the impact of a number of different funding scenarios on network condition over the next 5 to 10 years. Initial analysis indicates that the budget required to maintain trunk road structures at current condition levels aligns with the figures shown in Figure B.6. Key components of our strategy for managing trunk road structures are provided below. Planned and reactive maintenance programmes will be kept under review and the case for smaller more limited schemes considered on a whole life cost basis to ensure a safe network is maintained. This equipment includes basic sounding and probing equipment, moisture meter, stress wave timer and resistance drill. Three sets of equipment are available for use.The equipment will be shipped to your organization, and your organization will be responsible for returning the equipment to the MnDOT Bridge Office. Paul, MN 55155-1800 651-296-3000 Toll-free 800-657-3774. Continue acting safely to prevent the spread while supporting Alberta businesses. Find out how. Some routine maintenance actions are regularly scheduled, while other maintenance and repair actions are identified through Alberta Transportation’s Bridge Inspection and Maintenance (BIM) system. All bridge management decisions require inventory and inspection data on the structure to identify needs and appropriate actions. External users may login or request limited access to TIMS at the Alberta Transporation Extranet.

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The following user guides are available through TIMS and provide relevant information on bridge specific portions of TIMS data: The following documents describe this inspection process in detail: The certification of inspectors is described in the Bridge Inspection and Maintenance - Certification Process. The various Level 2 inspection types are described in the Bridge Inspection and Maintenance System - Level 2 Inspection Manual (Version 1.1 - March 2007 - pdf). Results of all assessments are tracked and used to develop bridge programs and support funding requests. See Bridges and structures - Assessments for more information. It is reproduced from the proceedings of the Institution of Civil Engineers' Bridge Engineering Journal with the permission of the Institution of Civil Engineers ( ) and Thomas Telford Ltd. The system is based upon the principles of the Danish DANBRO Bridge Management System. Whilst the first manual in the series describes in general the operation of the Eirspan system, this and all following manuals describe in detail the various modules within Eirspan. These are the Dublin Tunnel (M50), the Jack Lynch Tunnel (N40) and the Limerick Tunnel (N18). The Dublin Tunnel and the Jack Lynch Tunnel are operated and maintained by Egis on behalf of TII. Direct Route are responsible for the operation and maintenance of the Limerick Tunnel as part of the N7 Limerick Southern Ring Phase II PPP. It is a source of reference for planning, estimating, and technical accomplishment of maintenance and repair work and may serve as a training manual for facilities maintenance personnel in the Army and Air Force engaged in maintenance inspection and repair of bridges. The goal of 'Whole Building' Design is to create a successful high-performance building by applying an integrated design and team approach to the project during the planning and programming phases. Disclaimer. By using our website you agree to our use of cookies.

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Visited by some 830,000 sightseers every year it is famous the world over as an icon of England's capital city. In 2019 the bridge celebrates its 125th anniversary. John M. Smith describes its genesis and construction, the larger-than-life characters that drove the project forward, and the novel technologies employed in the bridge's design and operation. Supported with a wealth of fascinating original drawings, historic and contemporary photographs, the Haynes Tower Bridge Manual takes readers the behind the scenes to reveal the innermost workings of this major London landmark. show more Visited by some 830,000 sightseers every year it is famous the world over as an icon of England’s capital city. Opened in 1894, Tower Bridge is a combined bascule (a moveable bridge with a counterweight) and suspension bridge that spans the river Thames near the Tower of London. Widely revered as an engineering marvel of the Victorian age, it was built with giant moveable roadways that can be raised to allow passing ships to enter the Pool of London. In 2019 the bridge celebrates its 125th anniversary Civil engineer and author John M. Smith tells the story of this unique structure, describing its design and construction, the larger-than-life characters who drove the project forward, and the novel technologies employed in the bridge’s design. Also included is a close-up look at the operation, control and maintenance of the bridge in the 21st century. Supported with a wealth of original drawings and historic and contemporary photographs, the Haynes Tower Bridge Operations Manual takes readers the behind the scenes to reveal the innermost workings of this major London landmark. About the author John M. Smith BSc (Hons) MSc FIET FBCS CITP CEng is a Chartered Engineer and author. He has published widely in the engineering press and lives in Berkshire. show more He is published regularly in the model engineering press and lives in Berkshire. show more.

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A passenger vehicle trajectory database used to represent heavy ve hicle trajectories would include some trajectories th at are clearly difficult to attain for heavy vehicles. Passenger vehicles are smaller, have bett er braking and acceleration char acteristics as well as different inertial properties.The maximum achievable encr oachment angle using the equation above was compared to the actual encroachment angle for each of these 787 trajector ies. If the actual encroachment angle was greater than the maxi mum achievable encroachment angle for single- unit trucks or tractor trailer trucks it was excl uded from the heavy vehicle trajectory database. For single-unit trucks, 315 traject ories were found where the actual encroachment angle was less than the maximum achievable and 253 trajectories were found for tracto r trailer trucks. A trajectory database for both single-unit trucks an d tractor-trailer trucks was created using this data. The maximum encroachment angle in th e new trajectory database s used for both single- unit trucks and tractor-trailer trucks is 32 degrees. Coincidentally, BCAP limited all encroachment angles to 36 degrees. The exclude d trajectories represent high-angle, high-speed passenger vehicle encroachment trajectories that would be highly unlikely for trucks. Both BCAP and previous versions of RSAP made the assumption that trucks and passenger vehicles encroach at the same rate while limiting the encroachment angle and speed. Ray et al found that heavy vehicles encroach at a ra te 25 to 30 percent of the passenger vehicle encroachment rate. (9) The selection tables were develope d with this reduced heavy vehicle encroachment rate. Low Volume Encroachments The 1989 GSBR was developed using the pr ogram BCAP which used a constant encroachment rate based on the Hutchison-Kennedy data. RSAP and RSAPv3, in contrast, use a variable encroachment rate based on the Cooper data.

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RSAP v3 generally calculates th e mid-life number of encroachments and then uses that value in calcul ating the expected crash costs. If the mid-life ADT turns out to be on the top of the “hump” th e encroachments would be overestimated for the entire life and if the mid-life ADT occurs at the bottom of the “trough” the encroachments would be underestimated. In order to avoid this phenomenon, which only happens at low AADTs, an algorithm was added to RSAPv3 to calculate the nu mber of encroachments at 10 equally spaced times over the life and then take the average of th ese values to estimate the encroachments at the mid-life. A traffic growth rate is used to estimate the traffic volumes at these future points in time. This is a more realistic estimate of the average encroachment rate over the life o f the project, however, a traffic growth rate must be assumed in order to develop selection tables. Many traffic engineering s ources like the Highway Capacity Manual (HCM) use or recommend a default traffic growth rate of two percent. Similarly, the 1989 AASHTO GSBR assumed a two percent traffic growth as well, ther efore, a 2 percent annual traffic growth rate was assumed. A process is provided to adjust th is assumption and presente d in the next section. Project Life The 1989 GSBR assumed a 30-year life for br idges. The AASHTO Red Book generally recommends a 30-year service life for most transportation projects but the AASHTO LRFD Bridge Design Specification recommends in Section 1.2 a 75-year serv ice life for bridge structures. (10, 11) Replaceable portions of a bridge are sometimes assumed in the AASHTO LRFD specification to have a service life of between 30 and 50 years assuming that the Bridge railings are certainly a long-lived portion of a bridge structur e that would generally be replaced only if the structure is being replaced or if the deck is being replaced or refurbished.

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Choosing a longer service life amortizes the cons truction cost over a longer period of time so higher performance railings would be cost benefici al at lower traffic volumes. Conversely, a shor ter service life amortizes the construction cost over a smaller period so higher performance railing s would be cost beneficial at somewhat higher traffic volumes. A 30 year design life was used in the development of these selection guidelines, however, a process is provided to adjust the design life. Adjustments The 1989 AASHTO GSBR includes three adjustme nt factors; a horizontal curvature adjustment factor, a grade adjustment factor and an adjustment factor for deck height and under- structure conditions. The adjustments for the grade and horizo ntal curvature from the 1989 AASHTO GSBR are shown in Table 3. These values were also used in RSAP 2.0.3 as well as the latest version of RSAP, RSAPv3. While NCHRP 17-54 is in the process of updating these adjustments, the values shown are the best available data at the present time. These adjustment factors should be used until suitable replacements can be ma de. RSAPv3 also includes a number-of-lanes adjustment factor (f LN ), access density (f AD ), lane width (f LW ), and posted speed limit (f PSL ) shown Table 3. Bridge Railing Penetration Severity The 1989 AASHTO GSBR also included a bridge height adjustment to adjust for the severity of the under-bridge conditions. The ad justment was applied in appropriately in the 1989 AASHTO GSBR since the increase in severity should only apply to those cases where the vehicle penetrates the bridge railing whereas the GSBR applie s the factor to all crashes regardless of whether a penetration occurred or not. In RSAPv3, the condition of the area under the bridge is accounted for by a spec ial edge hazard.

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The severity of crossing the special edge is only calculated and included for those cases where the vehicle actually crosses the special edge by penetrating, rolling over or vaulting over the bridge railing. RSAPv3 uses a very different severity met hod based on observed crash data. Striking a bridge railing actually includes several possible outcomes in RSAPv3—the severity of the crash with the bridge railing itself, the possibility of being redirected into another hazard (i.e., striking another barrier or rolling over in the roadway) and penetrating or ro lling over a barrier. Penetrating through or rolling over the bridge rail is represented by the edge-of-bridge hazard in RSAPv3. The severity of this hazard is a f unction of characteristics of the area beneath the bridge. While each bridge rail has a distinct probability of penetration which does not change with the area around the bridge, th e possibility of causing harm af ter the penetration occurs does change depending on the characteristics of the ar ea beneath the bridge. For example, a bridge railing on a bridge in a very rural area over a st ream will cause no harm to others aside from the occupants of the vehicle whereas the bridge railing on a bridge ove r an urban street in a heavily populated area has much more potential fo r causing harm to non-motorists and other infrastructure. This difference in the conse quences of penetrating the bridge railing is accounted for through three types of edge-of-bridge hazards as follows: Nearby facilities where a collision could lead to a catastrophic loss of life such as chemical plants, nuclear facilities or water supplies should be considered high-hazard environments. A high-hazard environment is also present if penetration or rolling over the bridge railing could lead to the vehicle damaging a critical structural compon ent of the bridge (e.g., a through-truss bridge).

Penetrating the railing has the possibility of causing at least one non-moto r vehicle injury or fatality. LOW: A low hazard environment below the br idge includes water bodies not used for transportation, low-volume transpor tation facilities, or areas without buildings or houses in the vicinity of the bridge. Penetrating a low hazard railing would have little impact on regi onal or local transportation facilities. A low hazard railing has no buildings or facilities in the area which present possible non-motor vehicle relate d victims of a rail penetration. The Equivalent Fatal Crash Cost Ra tio at 65 miles per hour (i.e., EFCCR 65 ) method described in the RSAPv3 Engineer ’s Manual and a census of bridge rail crash data was examined from Pennsylvania, Ohio, and Nebraska. (8) Only 38 penetrations were found in these censuses of crash data. These 38 bridge rail penetratio ns provide possibly the only understanding of the consequence of penetrating a bri dge rail. The severity of a cr ash which does penetrate the rail was determined from this census of data. Th ese crashes are gathered from a census of police reported data, removing any bias toward more catastrophic crashes which may be more news- worthy but lack a statistical context. No moto rcycles, 26 passenger cars, and 12 heavy vehicles penetrated the bridge rails resulti ng in five fatal crashes, 13 A injury crashes, 5 B injury crashes, 6 C injury crashes, 8 PDO crashes and 1 crash of unknown severity. This results in an EFCCR of 0.1584. This number was used to represent th e medium level hazard discussed above. A value of 0.0584 is suggested for the Low-level discu ssed above. A value of 1.0000 is suggested for the High-level, which equates These EFCCR values represent the expected severity of vehicle pene trating the bridge rail and falli ng into the area below the bridge. The low severity bridge rail pe netrations have a severity that is similar to an on-road rollover (i.e., 0.

0220) which seems reasonable si nce in both cases vehi cle occupants and the vehicle itself are the only cost components that ar e at risk. Additional Considerations After reviewing temporal variations in both the crash and construction costs for the last decade, it was determined that crash costs have been continually increasing while construction costs have experienced a decreasing trend for the same period. These diverging values will have tremendous implications to benefit-cost analys is conducted from one year to the next. For example, an alternative which was cost-ben eficial in 2010 when construction costs were relatively low may not have been cost-beneficial in 2008 when c onstruction costs were higher. These significant changes can impact the choi ce of a preferred alternative when using an incremental benefit-cost analysis. While benefit-cost will always be a va luable tool for choosing among feasible alternatives, the temporal and regional variation found during th e conduct of this research for both crash costs and constructi on costs create a problem when developing national guidelines that are intended for long-term use ac ross all regions of the country. Another approach not often used explicitly in roadside safety but common in many other types of engineering fields is risk analysis. In risk analysis the risk of experiencing a particular type of event is quantifie d using probabilistic models. An accep table level of risk is established over the project life and then the system is engin eered to ensure that the risk in-service is below the targeted acceptable risk. For example, a transportation agency might decide that if the risk of a severe or fatal injury over the 30-year life of the project is less than 0.01 it is acceptable. Benefit-cost as used in roadside safety is ac tually a risk assessment method which is used to estimate the reduction in anticipated crash co sts (i.e.

, the benefits) which are then used to perform a standard benefit-cost analysis th at includes agency co sts like construction, maintenance and repair over the life of the proj ect. Roadside safety analysis programs like Roadside, BCAP and RSAP have always calculate d the average expected cost of crashes by simulating tens of thousands of possible encr oachments and then multiplying by the expected number of encroachments each year. The selection guideline have been generated us ing a risk based approach to (1) eliminate these concerns over diverging c onstruction and crash cost and (2 ) present selection guidelines which are applicable on a national level. Develo ping the selection guidelines using this approach has the added benefit of allowing the selection guidelines to be applicable to both new and retrofit construction because the cost of de molition need not be considered for retrofit construction, only the risk goal is considered. Selection Process The first step in the selection process is to determine the anticipated construc tion year traffic volume (AADT) and percent trucks (PT). This pr ocess assumes an annual traffic growth rate of 2 per year and a design life of 30 years. If the anticipated growth rate or design life are The third step in the selection process is to estimate the total number of encroachments (N ENCR ) that will be experienced during the life of th e bridge railing by entering Table 4 with the bi-directional construction year AADT from St ep 1 and the highway type (i.e., divided, undivided, or one-way). Multiply the value from Table 4 by total adjustments (f TOT ) from Step 2 to obtain N ENCR. Number of Access Point s on Bridge or wit hin 200 ft of either end Undivided Divided and Oneway Avg.The line was incl uded so that it is clear to users that the desired criteria could not be met even with a TL5 br idge railing.

In such a situation, however, there would be little al ternative to using a TL5 bridge railing so exceeding the risk criteria does not really change the selection. Th is line could be removed if it is found to be confusing for users. The fifth and final step in the selection process includes the consideration of factors not explicitly addressed by th e selection guidelines. The bridge railing selected using this process provides a solution where the risk of observing a severe or fatal injury crash over the design-life of the bridge railing should be less than 0.01 when the specific site conditions evaluated (i.e., traffic volume and mix, geometry, posted speed limit, and access dens ity) are considered. Engineering judgment should be used when unusua l or difficult to characterize site conditions are encountered when selecting a br idge railing. Limited numbers of crash tested bridge railings are available at some test levels, therefore, it is possible that the recomm ended test level barrier for the evaluated site conditions may not be the best choice for some site conditions not explicitly addressed in these se lection guidelines. For example, the particular layout of the barrier at the end of a ramp may influence inte rsection sight distances and require the use of engineering judgment in designing the interchange to determine an appropriate barrier as it approaches the intersection. Another example might be the presence of pedestrians or bicyclists which might benefit from a higher or different type of railing or the use of sidewalks. Some of the factors that should al so be considered are: a. TL5 bridge railings may be appropria te for specially designated hazardous material or truck routes. b. Intersection sight distance obs tructions created by higher te st level bridge railings at the ends of ramps or bridges should be considered and the bridge railings may require transitioning to a lower height approaching the intersection. c.

Stopping sight distance on bridges where th e radius and design speed plot below the dashed line in Figure 3 may limit the us e of higher test level bridge railings. d. The presence of pedestrians, bicyc lists, snowmobiles, ATVs and other recreational vehicles may affect the choice of bridge railing. e. Crash history especially as it relates to heavy vehicle crashes or bridge rail penetrations may justify higher performance bridge railings. f. Regional concerns about snow removal, hydrological impact of flood waters flowing over the bridge, and maintaining scen ic views may also play a role in the selection of bridge railings beyond these selection guidelines. g. The capacity of the bridge deck may limit the choices available for higher test level bridge railings on rehabilitation projects. These converted tables are shown in Figure 4 on the left side. While the purpose of this research is not to mimic the 1989 AASHTO GSBR guidelines, those earlier guidelines do provide some insight into wh at roadside safety engineers in the past have considered “r easonable” selection gui delines. The proposed selection guidelines are, therefore, compared to the 1989 GSBR and the NCHRP 22-08 selecti on guidelines to gauge how these new guidelines compare to what was accepted to some degree in the past. Figure 4 shows the recommended risk figure for a medium hazard in the center overlaid on the 1989 GSBR guidelines. It appears the recommendations from this research are slightly more conservative than the 1989 GSBR for a lifetime ri sk of 0.01. Figure 4 also shows the risk of 0.03, which more closely matches the 1989 GSBR guidelines. Under these assumptions, any trajectory has a lower severity (i.e., slower speed and same angle) the farther the vehicle travels so wider shoulder widths always result in reduced crash severity. RSAPv3, as discussed above, uses actual traj ectories collected in NCHRP 17-11 and 17- 22.

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