Maintenance of low volume poor condition pavement roads - Final report

The level of service at public roads is presently defined by technical basis with road condition and functionality. This Maintenance of Low Volume Poor Condition Pavement Roads project deals with low volume road level of service, typical problems and maintenance alternatives from operative, economical and customer oriented point of view. Within this project is introduced new alternative pavement condition parameters and management systems considering factors of road user level of service to improve maintenance of low volume roads. Low volume pavement road network (all connecting roads and regional highways with ADT less than 200) length is 25 600 km which is about 32% of all public pavement roads in Finland. Nearly 90% (22500 km) of these low volume roads have average daily traffic less than 1000 vehicles/day. On the grounds of driving comfort research the most uncomfortable pavement surface damages from road user viewpoint are holes, poor-quality patching, all kinds of stepped cracking and road edge depression. Windingness and hilliness of the road does not reduce passenger car traffic level of service as much as pavement surface damages or unevenness. Heavy vehicle drivers regard single high bumps causing extreme vertical movements (such as frost heaves) as highly significant driving comfort and traffic safety deteriorating factors. Evaluation of low volume road condition should be based on longitudinal and transverse unevenness (IRI and Cross_Ridge) and entirely new parameter VSt, which is based on the level of service of the road users. Single high bumps should also be defined from the road network. These new procedures presume some changes to the Finnra Road Condition Data Bank and pavement management system PMS. Measuring the single high bumps needs also generating new calculation algorithm to the measuring system. New parameters with failure criteria for the PMS are not necessarily directly suitable for the whole road network in Finland, because parameters are based on low volume pavement road network. Primary pavement damage survey development items discuss how serious level of pavement damages are, stepped cracking and poor-quality patching themes. Returning SOP (Gravel road surface treatment) road back to gravel road is not reasonable until SOP maintenance costs are greater than costs of gravel road maintenance. It is economically worthwhile to try to extend the service life of low volume roads, targeting to the basic level of service. Suitable ADT boundary for SOP road improvement measures (returning to gravel road or new asphalt pavement) is 100 vehicles/day. Boundary setting means that returning back to gravel road can be considered together with social factors if ADT is less than 100. If ADT is greater than 100, gravel road is generally not a realistic alternative. This report may be found at http://alk.tiehallinto.fi/julkaisut/pdf/3200957-vheikkokuntpaallystetyn_alemmantieverkonyllapito.pdf