A shift in modal share from car driving to cycling has many benefits, e.g., health benefits from increased physical activity and less pollution and congestion. A smooth cycle path surface with sufficient friction is important for cyclist traffic safety, comfort and level of service. Cracks and surface unevenness are frequent maintenance-related deficiencies associated with the degradation of the structure. A purpose of this thesis is to identify degradation factors specific for cycle paths, through a state-of-the-art literature review. The review is complemented by four appended papers. Paper A analyses the stated distress modes and causes reported on Swedish municipal cycle paths with respect to climatic and population data. Paper B evaluates a novel method for condition assessments on cycle paths related to cycling comfort—the Bicycle Measurement Trailer. PaperC proposes alternative deflection bowl parameters for structural evaluation of cycle paths from in-situ falling weight deflectometer and light weight deflectometer measurements. Paper D reports on the results of full-scale testing on instrumented cycle path structures. The main results from the papers indicate that surface roughness and unevenness, longitudinal cracks and edge deformations are the most common distress modes. The main reasons behind this distress are structural interventions, tree roots, frost heave and heavy vehicles. The load-bearing capacity close to the pavement edge and at increased moisture content is reduced. The proposed alternative approaches for cycle path condition assessment were able to assess the surface roughness and evenness, along with the structural condition, for practical applications on the investigated cycle paths. The conclusions of the thesis suggest that the structural design principles for cycle paths in the Swedish structural design manual needs to be updated. Models that better describe the behaviour of thin-surfaced asphalt pavements, especially with respect to climate, should be developed. More studies are recommended to validate the proposed condition assessment approaches.

En förflyttning av bilresor till cykeltrafik har många fördelar, t.ex. förbättrad folkhälsa genom ökad fysisk aktivitet och minskade föroreningar och trängsel. En slät yta med adekvat friktion är viktigt för cyklisternas trafiksäkerhet, komfort och framkomlighet. Sprickor och ojämnheter är vanligt förekommande underhållsrelaterade brister som är kopplade till cykelvägens nedbrytning. Ett syfte med den här avhandlingen är att identifiera specifika nedbrytningsfaktorer för cykelvägar. Det görs genom en litteraturgenomgång och fyra vetenskapliga artiklar. Paper A analyserar skador och skadeorsaker, som rapporterats av svenska kommuner, med avseende på klimat och befolkningsdata. Paper B utvärderar en ny metod för tillståndsbedömningar av cykelvägar som beaktar cyklisters komfort—Cykelmätvagnen. Paper C föreslår en uppsättning alternativa deflektions bassängparametrar för hållfasthetsutvärdering av cykelvägar baserat på fältundersökning med fallviktsmätningar. Paper D rapporterar resultat från fullskaligare sponsmätningar på instrumenterade cykelvägskonstruktioner. Huvudresultaten från artiklarna indikerar att lokala ojämnheter, längsgående sprickor och kantdeformationer är de vanligaste skadetyperna. De vanligaste bakomliggande orsakerna uppges vara avgrävningar, trädrötter, tjällyft och tunga fordon. Cykelvägens bärförmåga minskar i närheten av cykelvägskanten och vid ett ökat fuktinehåll i konstruktionen. De föreslagna metoderna för tillståndsbedömning av cykelvägar visade sig kunna bedöma cykelvägytornas textur och jämnhet samt det strukturella tillståndet på ett bra sätt för de undersökta cykelvägarna. Avhandlingens slutsatser poängterar att principerna för dimensionering av cykelvägar enligt Trafikverkets krav eller rekommendationer bör uppdateras. Modeller som bättre beskriver tunna asfaltkonstruktioners beteende bör utvecklas, speciellt när det gäller hur de påverkas av klimatfaktorer. Mer studier behövs för att validera de föreslagna tillstånds bedömningsmetoderna.

Assuring sufficient structural stability of cycle paths is important to avoid distress. Being thin and narrow structures, they are highly susceptible to edge cracking by passings of heavy vehicles. Two important factors that affect distress are lack of lateral support at the edge and increased moisture content in the unbound granular materials. Three full-scale instrumented cycle path structures with different structural design were constructed in a concrete pit at a test facility. Response measurements were conducted with a falling weight deflectometer, a light weight deflectometer, and light, standard and heavy maintenance vehicles at three different groundwater table scenarios. The results confirm reduced load-bearing capacity close to the edge, and at an increased groundwater table. In general, larger transverse tensile strains can also be expected in the asphalt layer close to the edge.

A recurrent challenge on cycle paths are edge cracks, which affect the traffic safety and accessibility of cyclists and produce high maintenance costs. Being both structurally thinner and narrower structures than roads, the cycle paths are extra prone to this problem. A few passages of heavy vehicles in unfavourable conditions might be enough to break the edge. The load-bearing capacity of eight municipal cycle paths in Linköping, Sweden, were assessed by falling weight deflectometer (FWD) and light falling weight deflectometer (LWD) measurements during a year-long cycle. A set of alternative Deflection Bowl Parameters (DBPs), better adapted to the structural design of cycle paths, were suggested and evaluated. The results of the FWD measurements showed that these suggested DBPs are a promising approach to evaluate the load-bearing capacity of cycle paths. From the results of the LWD measurements, it was found that the load-bearing capacity varies considerably with lateral position. The conclusion is that it might be more fruitful to measure the load-bearing capacity by LWD close to the edge, rather than the traditional approach of FWD measurements along the centre line of the cycle path.

Cyclists' riding comfort, related to pavement texture and unevenness, has not been thourougly investigated, partly due to the lack of condition assessment methods specifically adapted to the speed and space limits on cycle paths. Metrics that better describe the perceived comfort of cyclists, rather than that of car users, are needed. In this paper a novel method, the Bicycle Measurement Trailer (BMT), is proposed to bridge this gap. Eight different cycle path surface types have been assessed with regards to pavement texture and for four of these surfaces the longitudinal evenness was assessed. The accuracy and repeatability of the BMT were evaluated. Finally, five different metrics (Dynamic Comfort Index, Evenness Coefficient, 0.5 m Straight Edge, International Roughness Index and Root Mean Square), were calculated from the collected data and assessed. The main findings suggest that the BMT has a high accuracy at normal and high cycling speeds and a high level of repeatability at normal cycling speed. The surfaces could be ranked according to texture, and the evenness was successfully analysed. In conclusion, the BMT could be a valuable tool to assess the cycle path surface condition in relation to bicycle riding comfort.

There is a need to move society in a sustainable direction. One way to contribute to thismove is to change to more sustainable transport modes, such as cycling. To increase cycling, theinfrastructure is important, and good quality cycle paths are needed. However, little is known aboutthe degradation of cycle paths. This paper aims to investigate what modes of pavement distressare found on municipal cycle paths in Sweden, and what probable mechanisms lie behind suchdistress; these are determined based on questions from a state-of-practice survey, interviews, and aliterature review. The main findings are that the most commonly stated distress modes are surfaceunevenness followed by longitudinal cracks, and the most commonly stated causes of distress areageing, followed by structural interventions, and roots and vegetation. The results also show that forseveral distress modes, there are probable connections with climatic factors such as temperature andmoisture, as well as with the population size of the urban areas. Objective data are needed regardingtraffic load and the climatic factors that affect cycle paths, along with information on their structuraldesign, to better understand their degradation.

The riding comfort of cyclists related to roughness and unevenness of cycle path surfaces has unfortunately not been given enough attention in the indices used to predict cyclists’ perceptions of roadway environments. This is partly due to the lack of condition assessment methods specifically adapted to the speed and space limits on cycle paths, and a need for developing metrics that describe the perceived comfort of cyclists rather than that of car users. In this paper a novel method, the Bicycle Measurement Trailer (BMT), is proposed to bridge this gap. Eight different surface types, ranging from gravel and different sized concrete block pavements to asphalt concrete in different conditions, have been assessed with regards to roughness. Four of these surfaces were also used for the assessment of their longitudinal evenness. The accuracy and repeatability of the BMT were evaluated. Finally, five different metrics (Dynamic Comfort Index, Evenness Coefficient, 0.5 m Straight Edge, International Roughness Index and Root Mean Square), were calculated from the collected data and assessed. The main findings suggest that the BMT has a high accuracy at normal and high cycling speeds when compared to the standardized road measuring system, Road Surface Tester, and a high level of repeatability at normal cycling speed. The surfaces could be ranked according to their roughness, and the longitudinal evenness was successfully analysed from the collected data. In conclusion, the BMT could be a valuable tool to assess the cycle path surface condition in relation to how cyclists perceive the riding comfort.

Assuring sufficient structural stability of cycle paths is important to avoid distress. Being thin andnarrow structures, they are highly susceptible to edge cracking by passings of heavy vehicles. Twoimportant factors that affect distress are lack of lateral support at the edge and increased moisturecontent in the unbound granular materials. Three full-scale instrumented cycle path structures withdifferent structural design were constructed in a concrete pit at a test facility. Response measurementswere conducted with a falling weight deflectometer, a light weight deflectometer, and light, standardand heavy maintenance vehicles at three different groundwater table scenarios. The results confirmreduced load-bearing capacity close to the edge, and at an increased groundwater table. In general, larger transverse tensile strains can also be expected in the asphalt layer close to the edge.