| 1. |
- Erlingsson, Sigurdur, et al.
(författare)
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Influence of heavy traffic lateral wander on pavement deterioration
- 2012
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Ingår i: EPAM 2012. - Linköping : Statens väg- och transportforskningsinstitut. - 9789163714320
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Lateral wander of the traffic has an impact on the degradation development of pavements. This is usually not accounted for in the structural design process. Facilities with wide carriageways and broad shoulders tends to have relatively large lateral spreading while narrow road facilities lacking any shoulders can have highly channelized traffic pattern. In this research lateral wander characteristics have been measured for different road facilities. They can be assumed follow a normal distribution where the standard deviation describes their lateral spreading. Rut depth has thereafter been estimated according to two new rutting calculation scheme where lateral wander characteristics has been taken into account. The first approach is based on a two step mechanistic empirical (M-E) evaluation of the permanent strain in all layer of the structure and using a time hardening approach to sum up for all wander locations. This has thereafter been used to estimate the difference in rutting development as a function of the standard deviation. The second approach concentrates on calculating the permanent strain visco-elastically in the bound layers of the structure. Both procedures can be used to estimate the rate of relative deterioration for different road facilities. Based on the same structure the first approach give around 6 % increase in the surface rut as the standard deviation of the lateral wander increases from 10 to 20 cm. The second approach estimates this difference to be around 20 %. The difference between the two approaches are partly explained due to that the first approach estimates the rut based on all layers but the second approach from the bound layers only.
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| 2. |
- Erlingsson, Sigurdur
(författare)
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Mechanistic performance modelling of rutting in pavement structures
- 2012
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Ingår i: EPAM 2012. - Linköping : Statens väg- och transportforskningsinstitut. - 9789163714320
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A mechanistic empirical (M–E) approach has been developed and thereafter used to calculate the degradation behaviour of two arterial roads in Southern Sweden. The results were then compared with measurements from the Swedish long term pavement performance (LTPP) database. The M-E approach used was a two-step procedure where the response of the structure was calculated mechanistically and thereafter the performance predicted empirically based on scaling of laboratory test results. Extensive laboratory testing was carried out on samples taken from the test roads. Traffic counting and Bridge Weigh-in-Motion data were used to determine the amount of traffic loading, and data from weather stations were used to take into account the temperature dependency of the asphalt bound layers. The analysis shows that the rutting development can be simulated adequately although the calculations show slower rate than the measurements towards the end of the simulated period. The discrepancy in the rate of rutting between the measurements and the observations that was observed after about 9 years of operation might be due to the fact that no ageing or disintegration in material characterization was incorporated in the numerical analysis but surely observed in reality.
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| 3. |
- Karlsson, Robert, et al.
(författare)
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Follow-up study from a seven year performance contract ending in 2010
- 2012
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Ingår i: EPAM 2012: Malmö, Sweden, 5–7 September. - Linköping : Statens väg- och transportforskningsinstitut. - 9789163714320
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish Transport Administration aims at improving procurement of road construction and maintenance to create incentives for contractors to develop their skills and efficiency. Introduction of performance requirements is believed to encourage new technical solutions that are more adapted to object specific situations. In order to develop procurement procedures for performance contracts, the Swedish Transport Administration has initiated a number of pilot projects. Pilot project Road N610 included design, construction, maintenance and operation of a new road. It was initiated in 1999 by developing procurement documents and finally opened for traffic in 2003. The bids were evaluated following laws of public procurement based on technical solution, price, organization, quality assurance and references. The winning bid scored about average in these categories. In 2010, the contract ended and the responsibility was handed over from the contractor to the road administration. The requirements were related to both pavement layers (wear resistance, durability, stability) and road surface (friction, rutting, evenness, cross fall, cracking and ravelling). To ensure the long term performance, a requirement was also employed on the road’s structural strength based on a falling weigh deflectometer index. A bonus-malus system was tied to the requirements. The pilot project has been monitored closely and reports have been issued from the development of procurement documents and from the procurement and construction phases. This paper report experience gained with emphasis on the technical outcome. Observations from the construction stage and data from verification of performance confirm that the contractor has taken necessary measures to meet requirements and consequently adapted the pavement design and construction during the whole contract period to minimize costs and risks. A number of issues are identified with respect to future improvements in procurement procedures. A major client risk in performance contracts is related to ensuring long term performance at acceptable costs for maintenance and to identify responsibilities for inferior performance.
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| 4. |
- Rahman, Shafiqur, et al.
(författare)
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Moisture sensitivity of unbound granular materials
- 2012
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Ingår i: EPAM 2012: Malmö, Sweden, 5–7 September. - Linköping : Statens väg- och transportforskningsinstitut. - 9789163714320
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- One of the main structural units in thin flexible pavement is the unbound aggregate base course. It contributes to the overall load spreading mechanism of the structure due to traffic loading and provides an underneath support to the asphalt concrete layer. The material characteristic of unbound layers are therefore of great importance for the performance of the structure. Unbound base courses show stress as well as moisture dependent behaviour during external loading. This is true for both their stiffness and resistance against permanent deformation properties. A series of Repeated Load Triaxial (RLT) tests has been carried out on a typical unbound aggregate base layer to investigate its behaviour in order to improve the modelling of the moisture sensitivity. Both the resilient test and multi-stage loading approach have been used providing information on the resilient as well as the permanent deformation characteristics. Results showed that the stiffness decreases and permanent deformation increases with increasing moisture content.
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| 5. |
- Sjögren, Leif, et al.
(författare)
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Investigation of good practise in road assessment, Heroad
- 2012
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Ingår i: EPAM 2012Malmö, Sweden, 5–7 September : 4th European pavement and asset management conference. - Linköping : Statens väg- och transportforskningsinstitut. - 9789163714320
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To manage the road network road managers and operators have to consider existing policies such as the requirement to keep the network in good condition, and to deliver this condition at minimum whole life cost. However, the condition should also meet the expectations of stakeholders. The management process has to optimise the total costs for society, whilst minimizing the effects of given condition levels on safety, reliability, environmental impact, economics and sustainability. This principle and its overall goals are equal for all road managers around Europe. Heroad will investigate the process (the combination of individual components, levels of assessment and the inclusion of a life cycle perspective) to incorporate also new challenges in the asset management. This includes:Look at data collection, assessment and reporting regimesConsidering new challenges (climate change, traffic configuration, new materials, LCC and the focus on road users expectations)Identify and assess the key technical components of these regimes and then determine whether they are best practice or notIdentifying and describe indicators at different assessment levels (for road operators complicated technical parameters are okay, for decision makers and public more understandable indicators that could be built from combination of technical parameters are needed)Then pick out the key good parts and provide advice to the customer on how they could use them.
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| 6. |
- Wennström, Jonas, et al.
(författare)
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Microsimulation of work zone delays and applications in pavement management
- 2012
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Ingår i: EPAM 2012: Malmö, Sweden, 5–7 September. - Linköping : Statens väg- och transportforskningsinstitut. - 9789163714320
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Operation and maintenance activities on roads will to a varying extent affect the traffic flow.Reduced speed limits past the work zones will cause some delays but the main impacts will occur when the road´s capacity is reduced in case of lane closures. This increases the probability of queues which may contribute to significant delays for the road users. Delays result in costs for the society. Additionally, queues increase fuel consumption, pollutants, risk for accidents as well as wearing of vehicles and roads.This paper examines the use of microsimulation as a method to estimate the road user delays and discusses implementation issues and applications. The work zone delays have been implemented in a life-cycle cost analysis (LCCA) model. An LCCA was performed for the selection of wearing course type.The key finding of this study is that the high level of detail gives the opportunity to model different work zone types, road types and speed limits using one method. In comparison to other methods, most which are specifically developed for work zone analysis, microsimulation has previously been used in numerous traffic capacity studies. This gives a certain confidence, in conjunction with performed calibrations and validations, that the results are valid. The performed LCCA indicated that the road user delay costs contribute to a significant share of the total life-cycle cost. The delay costs did therefore affect the selection of wearing course with respect to the estimated life-cycle costs.
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