Sweden’s transport sector has emerged as a critical pillar of national security and civil defense in the wake of its NATO accession, with robust preparedness seen as essential for total defense. This paper reviews the increasing demands placed on the civilian transport system including the imperative to support military mobility, situational awareness, and continuity of societal functions under crisis. Recent government mandates and new guidelines from the Swedish Civil Defence and Resilience Agency (MSB) have accelerated the development of alternative technologies and operational strategies for road and rail infrastructure, emphasizing rapid, coordinated national readiness. Among the solutions explored are portable matting systems (PMS), rapidly deployable surfaces that serve as temporary roads when permanent infrastructure is compromised by disaster, conflict, or climate events. The expanding use of PMS in civilian, military, and disaster-response scenarios is driven by their versatility, sustainability, and suitability for challenging conditions. The review examines the evolution of matting systems from historic steel and aluminum panels to contemporary composite and polymer designs, with a focus on material properties, structural performance, and logistical considerations. Applications in construction, energy, emergency management, and defense are highlighted through case studies, alongside analysis of market growth trends in Europe and globally. The review further addresses challenges, including ground preparation, transport logistics, durability, recycling, and lifecycle environmental impacts. It concludes with recommendations for standardization, best-practice guidelines, and future research into advanced, digitally-enabled, and eco-friendly matting solutions, aiming to reinforce the resilience and sustainability of critical transport networks in a rapidly evolving security environment.  

Gravel wearing courses (GWC) on unpaved roads are exposed to traffic and severe climate, including freeze–thaw and repeated wetting–drying, which can lead to rutting, surface degradation and increased maintenance needs. Chemical stabilization is one way to improve performance, and lignosulfonate products are of special interest because they are bio-based binders already used as dust suppressants on gravel roads. Lignin is contained in the cell walls of plants and obtained as a byproduct of the paper and lignocellulosic industries (Misra et al., 2011). Lignin, representing the third largest fraction of plant biomass, is a large complex polymer of phenylpropane and methoxy groups, a noncarbohydrate polyphenolic substance that encrusts plant cell walls and cements plant cells together (Kim et. al., 2012). Most lignin-based industrial products in the forms of binder, dispersant, emulsifier, and sequestrant are derived from sulfite lignin (International Lignin Institute, 2008). Since lignosulphonates are by-products of other processes, they are relatively inexpensive and usually used as a dust control agent during gravel roads maintenance. This paper summarizes the behaviour of a lignin-based stabilizer, Listab, in comparison with an unstabilized reference GWC, based on a laboratory study in which both mixtures were tested under controlled freeze–thaw cycles (FTCs) and soaking–drying cycles (SDCs) using a laboratory light weight deflectometer (LWD).

Fuktinnehållet är en kritisk parameter för vägmaterialens prestanda, eftersom det påverkar packning, stabilitet och långsiktig hållbarhet. Traditionella gravimetriska metoder, såsom ugnstorkning, ger exakta referensvärden men är för långsamma för effektiv kvalitetskontroll på fältet. Denna studie utvärderar två bärbara dielektriska enheter, AquaProbe och MicroLance, med avseende på deras användbarhet för omedelbar bestämning av fuktinnehållet i vägbyggnadsmaterial. En litteraturgenomgång i kombination med laboratorieexperiment på lerig jord, siltig sand, sandig jord, återvunnet byggmaterial, bärlagrets ballast och skogsvägsmaterial gav en jämförande grund.

AquaProbe, som använder dielektrisk mätning i tids-/frekvensdomänen, kalibrerades med hjälp av ugnstorkade prover och visade starka linjära korrelationer (R² = 0,94–0,96) mellan direkta avläsningar och faktiskt fuktinnehåll, särskilt tillförlitligt i finkorniga jordar. MicroLance, som baseras på kapacitansavkänning med automatisk temperaturkompensation och snabb kalibrering på fältet, visade logaritmiska korrelationer (R² = 0,93–0,98) och visade sig vara särskilt effektiv för grovkorniga och återvunna material. Båda instrumenten framhöll fuktmätningens känslighet för materialtyp och packningsgrad.

Resultaten tyder på en dubbel strategi för praktisk användning: MicroLance som ett snabbt screeningverktyg för granulära och återvunna material och AquaProbe för dubbel övervakning och verifiering, särskilt i kohesiva jordar. Med lämplig kalibrering kan båda enheterna avsevärt öka effektiviteten, noggrannheten och tidsbesparingen vid kvalitetskontroll av vägkonstruktioner, vilket minskar riskerna i samband med dålig packning och förlänger vägens livslängd.

Moisture content is a critical parameter in the performance of road materials, influencing compaction, stability, and long-term durability. Traditional gravimetric methods, such as oven-drying, provide accurate reference values but are too slow for effective field quality control (QC). This study evaluates two portable dielectric-based devices, the AquaProbe and the MicroLance, for their applicability in instant determination of moisture content in road construction materials. A literature review combined with laboratory experiments on clayey soil, silty sand, sandy soil, recycled construction material, base course aggregates, and forest road materials provided a comparative basis.

The AquaProbe, which applies time/frequency domain dielectric measurement, was calibrated using oven-dried samples and demonstrated strong linear correlations (R² = 0.94–0.96) between direct readings and actual moisture content, particularly reliable in fine-grained soils. The MicroLance, based on capacitance sensing with automatic temperature compensation and rapid in-field calibration, showed logarithmic correlations (R² = 0.93–0.98) and proved especially effective for coarse-grained and recycled materials. Both instruments highlighted moisture measurement sensitivity to material type, and compaction state.

Findings suggest a dual strategy for practical use: MicroLance as a rapid screening tool in granular and recycled materials, and AquaProbe for dual monitoring and verification, especially in cohesive soils. With appropriate calibration, both devices can significantly increase efficiency, accuracy, and time savings in road construction quality control, reducing risks related to poor compaction and extending pavement life.

This study evaluates the structural performance of geocell–geotextile reinforced gravel roads constructed on waterlogged subgrades typical of Swedish forest environments. Three full-scale test sections were built: two geocell-reinforced sections using crushed rock and locally sourced material, respectively, and one conventional unreinforced reference section with nearly double structural thickness. Laboratory characterization, lightweight deflectometer (LWD) testing, moisture measurements, surface profiling, and visual inspections were conducted immediately after construction and after eight months of environmental exposure and simulated traffic loading. The geocell-reinforced sections exhibited substantial improvements in bearing capacity, with dynamic deformation modulus (Evd) increases of 52–64% after trafficking compared with the unreinforced section. Profile measurements showed negligible rutting in reinforced sections, while the reference section developed visible deformation despite its greater thickness. The results demonstrate that geocell confinement combined with geotextile separation effectively enhances structural capacity and durability on weak saturated subgrades. Furthermore, the use of locally sourced infill material provided equal or superior performance compared with imported crushed rock, indicating potential for cost reduction and possible environmental benefits through reduced material transport and resource use. The findings support geocell reinforcement as a practical solution for improving accessibility, reducing material demand, and increasing climate resilience of forest gravel roads. 

Efficient and sustainable forest road construction is essential for the forestry industry, ensuring accessibility while minimizing environmental impacts. This study investigates the effectiveness of stone mattresses, also known as French mattresses, as a stabilization and drainage technique for forest roads in Sweden. A field trial was carried out on a forest road in Dalarna County, involving two nearby sections, Section 1 and Section 2, each approximately 200 meters in length. Each section was divided into two parts: one stabilized with stone mattresses and the other without, for comparison purposes. Stone mattresses, composed of coarse rock wrapped in geotextile, facilitate water drainage while enhancing road durability. Various tests, including lightweight deflectometer (LWD) measurements, profile surveys, material analysis, moisture assessments, and visual inspections, were performed before and after exposure to traffic and weather conditions. Results showed that road sections with stone mattresses exhibited improved bearing capacity, the rate of change in dynamic deformation modulus (Evd) was 12–23% higher than on unstable road surfaces. Additionally, these sections exhibited reduced rutting, indicating improved structural integrity and resilience. Further optimization of construction methods, as discussed in this study, could enhance efficiency, making the implementation of stone mattresses even more effective for stabilizing forest roads in challenging conditions.

This study investigates the modeling and prediction of permanent strains in subgrade soil using repeated lightweight deflectometer (LWD) testing. The research focuses on understanding the relationship between applied stress, recoverable strain, water content, and accumulated permanent strains, specifically in silty sand subgrade soils. In-situ LWD tests were conducted at different stress levels (50, 100, and 200 kPa) and water contents (8%, 10%, and 15%) to measure both permanent and recoverable deformations. A developed model, designed to predict permanent strains utilizing recoverable strains in road materials under various conditions, was compared with LWD results and evaluated for accuracy. While discrepancies were observed at higher water contents and certain stress levels using this model, the regression models demonstrated strong predictive capabilities, with R² values exceeding 0.91 for most testing conditions. This study underscores the potential of in-situ repeated LWD testing as a reliable tool for assessing subgrade behavior for pavement design.

This study evaluates soil stress distribution during LWD testing and refines Boussinesq's equation to better reflect actual vertical stress changes considering material properties. It examines the effects of soil type, moisture content, plate size and applied stresses on LWD's influence depth. Vertical stress sensor arrays in two geomaterials: large-scale in-situ tests and field material characterisation support the analysis. Notably, the suggested equation achieves significant error reduction compared to the original Boussinesq equation. 

For clayey soil, the results showed that the influence depth aligns with Boussinesq's theoretical predictions at about twice the LWD plate diameter. However, measured stress distribution in the field diverges from Boussinesq's equation for granular base material. Discrepancies stem from factors like particle interlocking, compaction energy and local moisture content. Significantly, measured stresses surpass Boussinesq's calculated values.

To address these discrepancies, a modified Boussinesq-based model incorporates local water content and field density, significantly improving vertical stress prediction accuracy. This adjustment reduces errors by 69.5% for clayey soil and 94.4% for granular material, highlighting the importance of material-specific properties in modelling vertical-induced stresses, particularly for LWD-induced stresses.

These findings enhance material behaviour prediction under dynamic loads, reinforcing mechanistic-empirical pavement design and enabling resilient, economical road infrastructure.  

Sweden's climate goals require innovative strategies for maintaining forest road infrastructure. Increasing the gross weight of timber transport trucks can significantly cut CO₂ emissions but also places added stress on gravel roads, demanding improved stabilization techniques. This study assesses the effectiveness of enzyme-based stabilization methods in enhancing the load-bearing capacity and durability of forest roads. Two test sections were constructed on a pilot road in Trosa, Sweden: one treated with Road Stabilizr (RS) and Dust Blokr-Sugar Blend (DB-SB), and another with TerraZyme (TZ). Field assessments, including lightweight deflectometer (LWD) testing, surface profiling, and visual inspections, were conducted before and after exposure to weather conditions and simulated traffic. Laboratory analysis confirmed that Trosa’s fine-grained material was suitable for enzyme-based stabilization. The results indicated that both stabilization methods improved the road’s structural strength, with LWD tests showing a 17 % increase in the dynamic deformation modulus (Evd) for the RS/DB-SB section and an 11.4 % increase for the TZ section after stabilization. Additionally, dust suppression benefits were observed in the RS/DB-SB section, contributing to reduced environmental impact and enhanced road longevity. This study highlights the potential of enzyme-based stabilization as a sustainable solution to improve forest road performance and minimize maintenance needs. 

Skogsbilvägnätet är nödvändig infrastruktur för svenskt skogsbruk och en förutsättning för att transportera rundvirke (massaved och timmer) och skogsbränsle samt möjliggöra skogsvård (markberedning, plantering och röjning) och andra åtgärder förknippat med skötsel och förvaltning av naturresursen skog. Skogsbilvägnätet står inför utmaningar på grund av begränsad bärighet och geometri. Anläggningsmetoderna måste utvecklas för att svara mot utmaningarna. Problemen förvärras av allt högre krav på Just-in-Time transporter, lägre lagernivåer i hela försörjningssystemet ökande bruttovikter samt klimatförändringar. Detta projekt har testat innovativa lösningar för att förbättra vägarnas hållbarhet, med deltagande av skogsföretag, transportutförare och forskningsinstitutet Skogforsk. 

Skogsföretagen som deltog i projektet byggde varsin provväg för att testa olika lösningar för att öka bärigheten.

• SCA byggde sträckor med varierande bombering och fann att 5 % var optimalt för prestandan, och testade dessutom fördelarna med att bygga en vattenanledningsgrupp eller vägbula för vattenavledning (rullande dipp) för förbättrad dränering utanför projektramen. 
• Holmen testade stabiliseringstillsatser vilket avsevärt förbättrade bärförmågan hos terrasser med lerhaltiga jordar, även om kostnaderna var högre på grund av bland annat vattning före stabilisering. Holmen fann också att en ökad packningsmetod för lerigt material ökade bärförmågan med 20 % för sin referenssträcka. 
• Sveaskog byggde en pilotväg i Överkalix på sandigt vägmaterial och försökte öka bärigheten genom ökad packning, men fann minimala fördelar på grund av vägens sammansättning. 
• Stora Enso provade användning av geoceller, vilket förbättrade bärigheten med upp till 64 % och gjorde det möjligt anlägga en grusväg på vattendränkt mark. Dessutom gav geocellerna betydande kostnads- och prestandafördelar jämfört med traditionella metoder. 
• Kopparfors förbättrade dräneringen med stenmadrasser och ökade bärförmågan baserat på deras placering och antal. 

En kostnadsnyttoanalys visade att Stora Ensos två geocellsarmerade vägar var de mest kostnadseffektiva, eftersom de uppnådde högre bärighet med lägre byggkostnader än referenssträckorna. Holmens kompakterade sektion visade också höga fördelar till låga kostnader och hamnade på tredje plats. 

Dessa innovativa metoder visar på lovande strategier för att förbättra de svenska skogsbilvägarnas prestanda och samtidigt balansera kostnader och miljöpåverkan.

Swedish forest roads are essential for transporting forest products but face challenges from outdated construction methods, erosion, and limited load-bearing capacity. These issues have been worsened by climate change, heavier transport loads, and the COVID-19 pandemic. This project tackles these challenges by testing innovative solutions to improve road durability, involving forestry companies, demand owners, and research institutes. 

In the project, each forestry company built a trial road to test solutions for increasing load-bearing capacity. SCA constructed sections with varied crown slopes of 10%, 5%, and 0%, The finding that a 5% crown slope provided optimal performance, and additionally tested the benefit of constructing a rolling dip for improved drainage out of the project frame. 

Holmen tested stabilization additives in Trosa, which improved bearing capacity, though costs were higher due to pre-stabilization watering. Holmen also found that an improved compaction method on clayey material boosted bearing capacity by 20% compared to its reference (unstabilized) road section. 

Sveaskog’s built a pilot road in Överkalix on sandy road materials and tried to increase the bearing capacity by increased compaction but found minimal benefits due to the road's composition. 

Stora Enso used geocells in Värmland, enhancing bearing capacity by up to 64% and making it possible, for the first time in Sweden's forest industry, to construct a gravel road on waterlogged soil. In addition, the geocells delivered substantial cost and performance benefits compared to traditional methods. 

Kopparfors improved drainage with stone mattresses in Ludvika, increasing bearing capacity based on their placement and number. 

A cost-benefit analysis highlighted Stora Enso’s two geocell-stabilized roads as the most costeffective, achieving higher bearing capacity with lower construction costs than reference sections. Holmen’s compacted section also showed high benefits at low costs, ranking third overall. 

These innovative approaches demonstrate promising strategies for enhancing Swedish forest road performance while balancing cost and environmental impact.

It is well known that unbound granular materials (UGMs) play a fundamental role as the base layer in flexible pavements. The dynamic properties, namely the resilient moduli, are quite important to characterize the unbound materials for the Mechanistic-Empirical Pavement Design Guide (MEPDG). The repeated load triaxial (RLT) test used to measure the resilient moduli is a rather expensive and time-consuming test. In this study, extensive research has been carried out to establish the relationship between the resilient moduli (Mr) measured by RLT tests and the dynamic deformation moduli (Evd) measured by a simpler technique, namely the Light Weight Deflectometer (LWD) tests, for a local type of commonly available unbound material in Sweden. To measure the dynamic material parameters using the LWD and RLT tests under similar test conditions, a series of in situ and laboratory LWD and RLT tests were carried out at different moisture contents and stress levels. The overall test results were analyzed, and a strong regression correlation (R=0.95) was found between the dynamic parameters measured from the RLT and LWD tests for the tested material.