Damage on forest roads as a result of improper construction

Sažetak Šumske ceste kao trajni građevinski objekti zahtijevaju ispunjene minimalno propisane kvalitete i standarda tijekom izgradnje. Prema dostupnim podacima prosječni troškovi gradnje šumskih cesta u F BiH za 2019. godinu iznosili su 22.282,19 € po dužnom kilometru (Anon 2019a). Ovako niski troškovi gradnje nameću opravdano pitanje kvalitete novoizgrađenih šumskih cesta i potrebno mu je posvetiti odgovarajuću pozornost. Na području F BiH, zbog niza razloga, sve se više grade prilazne ili tzv. tehnološke šumske ceste, koje se zbog činjenice da se radi o vrsti šumskih cesta bez izvedene kolničke konstrukcije mogu koristiti samo po suhom vremenu te zbog toga ne ulaze u obračun klasične otvorenosti šuma. Osim toga, zbog nedostatka odvodnih jaraka i prevelikog uzdužnog nagiba nivelete na ovim cestama mogu nastati nesagledive ekološke posljedice. S obzirom da postojeća otvorenost šuma u F BiH nije na zadovoljavajućoj razini, cilj svih šumarskih poduzeća je njeno povećanje. Kako se gradnjom šumskih cesta bez izvedene kolničke konstrukcije ne utječe na povećanje otvorenosti, količina cesta koju je potrebno izgraditi za dostizanje ciljane klasične otvorenosti ostaje nepromijenjena. Kao rješenje za riješavanje navedene situacije, u praksi se u posljednje vrijeme sve više grade šumske ceste s elementima koji čine kombinaciju sporednih i prilaznih šumskih cesta. U ovom radu je izvršena analiza tehničkih i konstruktivnih elemenata za novoizgrađenu šumsku cestu „Braćinac - Doljanske stijene“ stacionaže 1,72 km. Na osnovi dobivenih rezultata, došlo se do saznanja o elementima koje na ovoj cesti treba unaprijediti kako bi se ista očuvala, odnosno kako bi se omogućilo njeno dugogodišnje korištenje. S tim u vezi evidentirana su odstupanja uzdužnog nagiba nivelete u odnosu na propisane veličine na 41% od ukupne dužine, na 26% od ukupne dužine nagibi škarpi usjeka nisu prilagođeni kategoriji materijala u kojoj su izgrađene, duž cijele šumske ceste nisu izgrađeni odvodni kanali. Navedena odstupanja daju za rezultat propadanje kolničke konstrukcije, s obzirom da su na 24% evidentirana manja, a na 9% veća oštećenja. Imajući u vidu da su mjerenja na terenu urađena samo godinu dana nakon izgradnje šumske ceste, nameće se zaključak da niska kvaliteta gradnje i nepridržavanje tehničkih propisia rezultira ubrzanim propadanje ceste.SummaryForest truck roads are permanent buildings thet require certain kind of quality and standard for its building. Due to lack of financial resources, the quality of newly constructed forests truck roads in FBiH is becoming weaker with time. The aim of this paper is determination of quantitative and qualitative features of newly constructed forest truck roads in the last 10 years in the area of the Managment Unit (MU) “Zujevina” , Forest Managment Region (FMR) „Igmansko“. The analysis of newly constructed forest roads was performed on the basis of data obtained by field measurements, which were then processed in the office and compared with the features prescribed by the Technical Regulations. In the last 10 years, two forest roads with macadam-type carriageway were built within the MU “Zujevina”, which increased the absolute accessibility of the managment unit, which now amounts to 9.45 m/ha and is significantly lower than the accessibility recommended for such areas and that is 15 m/ha.By analyzing the technical and constructive features of the newly constructed forest road “Braćinac - Doljanske stijene”, it can be concluded that the average width of the road and the road shoulder width are within the intervals of the prescribed values.In the length od 41% of the total length of the road, this road is characterized by deviations of the slope of vertical alignment in relation to the prescribed values. On 59% of the total length of the road, the measured longitudinal slope is in accordance with the Technical Regulations.Side dithces were not built on the analyzed forest road, which is reason why atmospheric precipitation flows on the road surface, so in certain sections the quality of the road surface is poor and erosion occurs on the upper layer of the road.The average cross slope of the road does not meet the prescribed values for that element. From the recordings of the cut slopes, we conclude that there are sections, about 9% of the total length of the road, which need to be cut, and sections in the length of 26% of the total length, which require construction work in order to adjust the slope of the cut slopes to the category of material in which they were built.Analyzing the structural features, we obtained data showing that 67% of the pavement surface is undamaged, minor damage was recorded on 24%, while major damage was recorded on 9% of the total surface of the road.Out of a total of five pipe culverts, four pipe culverts perform their function without interruption, while one needs cleaning of the entrance.Field measurements were made only one year after the construction of the forest pavement and before the transport of wood assortments from the department that opens the road. The obtained results show that the low quality of construction and non-compliance with technical regulations results in accelerated deterioration of the road. The damage recorded on the road can be attributed to the impact of increased atmospheric precipitation, which as a result of global climate change is becoming more frequent and should be taken into account when projecting and building forest truck roads