This present ROADEX IV follow-up report describes results from demonstration projects in Scotland, Finland, Norway and Sweden over the period 2010 to 2012, where the case study from the Beaver Road 331 in ROADEX III has been reproduced. This document also reports on a study of the influence of road maintenance standard on truck ride vibration and vehicle internal noise, with special focus on winter road condition. Furthermore it reports on a study on vibration isolation from road to truck driver’s seat, by use of a Tyre Pressure Control System (TPCS). All measurements were carried out in the period 2010 - 2012.
A high repeatability between similar truck round trips was confirmed when using the ROADEX method to assess truck drivers’ daily vibration exposure A(8). Results from measurements of truck ride quality during the demonstrations included:
* Unacceptably high levels of driver´s daily vibration dose A(8) were recorded in all of the ROADEX Partner areas (the Norwegian E6-measurements were lower than the others but still at about the EU Action Value).
* Significant compression stress in the truck drivers spine were recorded at severe road damages, such as sharp frost heaves, settlements at bridges and culverts, improper
road/bridge joints and uneven transversal joints at both old and new asphalt repairs.
* In all Partner areas, intense truck roll vibration and lateral buffeting was recorded. This confirmed a special health and safety problem in the EU Northern Periphery (NP) cold
* The pavement condition parameter RBCSV (a “truck roll vibration indicator”) was further validated in addition to the previous ROADEX III study in Sweden. At sites with very high RBCSV, there is a risk that cargo latches might break due to high lateral acceleration.
* Winter conditions in the NP can result in significant corrugations in thick ice covering nonsalted roads, and extremely uneven frost heaves. The project results show that these conditions can make the ride vibration and noise much worse than during summer conditions.
* The use of a Tyre Pressure Control System (TPCS) has previously been shown to reduce ride vibration. The present study used a more detailed analysis to quantify the TPCS vibration isolating effect. Results from Scotland and Sweden show that TPCS was very efficient in isolating “shake” vibration from short wave road roughness (megatexture < 0.5 m) such as potholes and corrugated ice surfaces.
* Vehicle body “bounce” vibration with lower frequencies (1 – 3 Hz) were not isolated by the TPCS. Such low frequency bounce vibration can only be reduced by pavement maintenance.
* High side friction demand due to improperly banked horizontal curves was found to be a contributing factor behind many loss-of-control crashes, including rollovers.
* Several curves with tragic crash records were found to be improperly banked despite being newly resurfaced.