När stadsområdet Vallastaden i Linköping byggdes 2017 var ett krav att kunna utnyttja maximal markyta för bebyggelse. Det behövdes då ett alternativt sätt att anlägga VA-ledningar, då började utvecklingen av infrastrukturkulvertar. De utvecklade då ett helt system som ligger i en skyddad miljö och klarar av tätbebyggelse. Efter det har intresset hos flertalet kommuner väckts men det är fortfarande svårt att avgöra vilken metod som ger en större ekonomisk lönsamhet.Genom att utföra en teoretisk simulering i form av LCC-analys kan en slutsats dras utifrån den data som används. För att utföra den teoretiska simuleringen har litteraturstudier gjorts för att samla data som sedan använts i Excel.LCC-analysen har begränsats till kunskaperna utefter de förutsättningar som finns. Därav har beräkningarna fokuserat på schakt-, anläggning- och underhållskostnad.Resultaten visar att det finns en brytpunkt runt 40 år där en tydlig skillnad kan ses över de två systemens lönsamhet. Infrakulverten är teoretiskt billigare när simuleringen utförs med ett intervall på (+/-) 20 % av totalpriset. Studien visar även att infrastrukturkulverten har en mindre underhållskostnad vilket är en av de drivande kostnaderna när det kommer till simuleringen. Underhållskostnaden är en årlig återkommande kostnad vilket resulterar i att systemens kostnad ökar i olika takt utifrån deras underhåll.Slutsatsen är att infrastrukturkulverten är ekonomiskt lönsamt på sikt utifrån den undersökning som utförts i studien. Infrastrukturkulverten har även en lägre underhållskostnad men kan eventuellt ha en liten högre anläggningskostnad beroende på projektets storlek. / When Vallastaden, a neighborhood in Linköping was to be constructed in 2017 they had a requirement to be able to make use of as much of the land as possible for construction. It was necessary to come up with an alternative way to construct the water and sewage system, so the development of infrastructure culverts started. They developed a complete system which lays in a protected environment and manages close contact to buildings. This sparked the interest of several municipalities, but it is still difficult to decide which method is the most feasible financially.By performing a theoretical simulation like an LCC-analysis the decisions can be made based on the data used. In order to perform this theoretical simulation literature study has been done in order to collect the data which has been used in Excel.The LCC-analysis has been limited to the knowledge based on the existing prerequisites. Based on these prerequisites the calculations have focused on the excavation-, plant- and maintenance costs.The results show that the breakeven point lays around 40 years, a clear difference can be seen between the financial feasibility of both systems. Infrastructure culverts are theoretically cheaper when the simulation is done with an interval of (+/-) 20% of the total price. Studies have also shown that infrastructure culverts have lower maintenance costs, which are the majority of the costs when it comes to this simulation. Maintenance costs are a yearly recurring cost which result in the system costs rising based on their maintenance.The conclusion is that infrastructure culverts are financially profitable based on the research done in the study. Infrastructure culverts have lower maintenance costs but could potentially have higher construction costs based on the project size.

No description available.

Improperly designed road-stream crossings can fragment stream networks by restricting or preventing aquatic organism passage. These crossings may also be more vulnerable to high flow events, putting critical human infrastructure at risk. Climate change, which will require access to suitable habitat for species persistence, and is also predicted to increase the frequency and magnitude of extreme floods, underscores the importance of maintaining stream connectivity and resilient infrastructure. Given the large number of road-stream crossings and the expense of replacement, it is increasingly important to prioritize removals and account for the multiple benefits of these management actions. I developed an aquatic barrier prioritization scheme that combines potential habitat gain, stream thermal resilience, aquatic organism passage, and culvert risk of failure. To assess relative thermal resilience, I deployed paired air-water thermographs in several New England watersheds and analyzed relative thermal sensitivity (relationship of water to air temperature) and exposure (duration, frequency, and magnitude of warm stream temperature episodes) among streams. These were combined into a single metric of thermal resilience corresponding with the distance of that stream’s sensitivity and exposure from the watershed median. To test the relationship between risk of failure, culvert dimensions, and stream connectivity, I developed a logistic regression to predict risk of failure using data from two watersheds that experienced extreme flooding from Hurricane Irene (2011). Finally, I applied the resultant prioritization scheme to 66 road-stream crossings in the Westfield River watershed (MA). Thermal habitat quality varied considerably within and among watersheds. Stream sensitivity was generally lower than the widely accepted 0.8 ̊C increase in stream temperature for every 1 ̊C increase in air temperature (Westfield median sensitivity = 0.44), with substantial differences among streams. Exposure also varied widely among streams, indicating that some headwater streams in New England are more thermally resilient than previously thought. Risk of infrastructure failure was predicted with a logistic regression using culvert constriction ratio and predicted aquatic organism passage as predictors (Likelihood ratio test, X2=59.1, df=3, p- value=9.2e-13), indicating that underdesigned culverts were more likely to be barriers to passage and more likely to fail in extreme flow events. To prioritize culverts, this study ultimately used a piecewise approach that identified culverts opening the longest reaches of thermally resilient habitat, and then ranked those culverts by infrastructure replacement need. In the Westfield River, the prioritization clearly identified crossing replacements most likely to yield multiple benefits. The scheme I developed can accommodate changes in the relative weights of the different criteria, which will reflect differences in management and conservation concerns in the confidence of inputs. In conclusion, increasing connectivity by removing barriers may be one of the most effective ways to mitigate the effects of climate change on aquatic systems, but it is important to remove the right barriers.

In order to predict hydraulic jump characteristics for channel design, the jump height may be determined by calculating the subcritical sequent depth from momentum theory. In closed conduits, however, outlet submergence may fill the conduit entirely before the expected sequent depth is reached. This is called an incomplete or pressure jump (as opposed to a complete or free-surface jump), because pressure flow conditions prevail downstream. Since the momentum equation involves terms for the top width, area, and centroid of flow, the subcritical sequent depth is a function of the conduit shape in addition to the upstream depth and Froude number. This paper reviews momentum theory as applicable to closed-conduit hydraulic jumps and presents general solutions to the sequent depth problem for four commonly-shaped conduits: rectangular, circular, elliptical, and pipe arch. It also provides a numerical solution for conduits of any shape, as defined by the user. The solutions conservatively assume that the conduits are prismatic, horizontal, and frictionless within the jump length; that the pressure is hydrostatic and the velocity is uniform at each end of the jump; and that the effects of air entrainment and viscosity are negligible. The implications of these assumptions are briefly discussed. It was found that these solutions may be applied successfully to determine the subcritical sequent depth for hydraulic jumps in closed conduits of any shape or size. In practice, this may be used to quantify jump size, location, and energy dissipation.

The study is a comparative desk study of the application of the vertical earth load, traffic live load and the nominal earth pressure in the design methodology of culverts as outlined in TMH7 – Code of Practice for the design of highways bridges and culverts in South Africa Part 2, AASHTO LRFD Bridge Design specification and the DMRB volume 2 section 2 part 12 - BD31/01. It involves the theoretical design and analysis of five single cell reinforced concrete box culverts ranging from 2.1m to 6.0m under different fill depths ranging from 0 to 8.0m by applying load obtained using the three design manuals. The objective of this study is to analyze the methodology involved in estimating vertical earth load on a culvert as outlined in the design manuals to ascertain relevance of the formulae and procedure in TMH7 or/and to recommend the most effective approach for evaluating the vertical earth load on box culverts specific and appropriate for South Africa. By comparing the load derivation methodology outlined in ASHTO LRFD and BD 31/01 and analyzing the load forces obtained from the analysis. Box culverts are designed as rigid monolithic structures to withstand the maximum bending moment and shear force. The design involves the analysis of the various loads acting on the culvert with the weight of the overhead earth embankment being the most significant. The vertical earth load, live load and the lateral earth pressure acting on the culverts at various fill depth are manually derived from equations as outlined in the three design manuals. The culverts are modelled and analyzed in Prokon as two-dimensional plane frame structures using the frame analysis module by applying this load to determine maximum positive hogging moments, maximum negative sagging moments and maximum positive shear forces for each span for the top slab. The load forces obtained for each span are then plotted against the soil cover depth to illustrate the discrete load effect of the vertical earth load and live load on the culverts at varying fill height and to determine the relationship between the culvert geometry, soil cover depth and the applied load. The result of the analysis shows that an increasing non-linear relationship exists between the load effects, the soil cover depth, and the span length. The dead load effect increases with increasing fill depth and culvert span while the live load effect diminishes with increasing fill height and culvert span i.e., for culverts buried at shallow depths, the traffic live load is the most critical load but as the height of the soil cover increases the dead load becomes more significant until a point is reached where the live load is totally insignificant. The vertical earth loads obtained from TMH7 and BD31/01 are constant at a particular fill depth for each culvert despite the different span length. The vertical earth load for these two manuals is estimated from the soil cover depth and density, the load tabulated clearly is independent of the culvert geometry. The load obtained from AASHTO LFRD is the lowest and less than 20% of the load obtained from the other two design manuals. Unlike TMH7 and BD31/01, AASHTO LFRD considers the effect of the soil-structure interaction to adjust the vertical earth load on the structure which automatically reduces the load value. The vertical earth load values obtained from TMH7 and BD31/01 are generally more conservative as compared to those obtained from AASHTO LFRD.

No description available.

No description available.

No description available.

No description available.

No description available.