Final shortlisted options

Introduction

The final shortlisted options are described below and shown in Figure 17.

Single Lane Forestry Track Upgrade The Single Lane Forestry Track Upgrade option generally follows the route of the existing Glen Croe lower forestry track as it rises up the southwest side of Glen Croe, within the lower slopes of Ben Donich. This option commences at the existing, at-grade, direct access from the A83 Trunk Road into the now gated and closed original access to the OMR, and then initially follows the alignment of the OMR before turning left to cross the Croe Water approximately 135m downstream of an existing structure across the watercourse. Beyond the Croe Water crossing, it turns right and then generally follows the route of the existing Glen Croe Lower Forestry Track along the western bank of Croe Water. After a short distance it rises away from the Croe Water and then follows the general alignment of the Glen Croe Lower Forestry Track for several kilometres within the lower slopes of Ben Donich. As it emerges from Glen Croe Forest, it follows the general alignment of another track, the Glen Mhor Forestry Track, which heads north to form an at-grade direct access with the B828 Glen Mohr local road. This option then includes a length of the B828 Glen Mohr local road and concludes where this local road joins the A83 Trunk Road again via an at-grade junction. It is approximately 4.1 km long, measured between the two points at which it meets the A83 Trunk Road. The Single Lane Forestry Track Upgrade option drawings are included as Appendix A of this report. OMR Interventions The OMR Interventions option consists of a number of interventions to improve the operation and resilience of the OMR when used as a diversion route. The proposed interventions include an increased length of two-way working; providing edge protection where there is increased risk that a vehicle leaves the carriageway and would otherwise encounter a hazardous feature, and edge markings for delineation of the road; curve widening to reduce risk of incidents on the tight bends; improved resilience of existing structures, including bridge widening and potential strengthening works; improved resilience of culverts; potential realignment of the southern A83/OMR junction to reduce flooding impacts; and geohazard mitigation measures for debris flows and boulder falls in the form of bunds and catch fences. The OMR Interventions drawings and schedule are included as Appendix B of this report. Offline MTS Option The Offline MTS option generally follows the LTS Green Route on the western slopes of Glen Croe within the lower slopes of Ben Donich. It consists of a two-way single carriageway with verges. The option is approximately 3.5km long. This option commences at a junction with the A83 Trunk Road, approximately 200m north of the current junction with the OMR, and crosses Croe Water before heading westbound to join the alignment of the LTS Green Route, where they overlap horizontally and vertically for approximately 2.0km. Where the LTS Green Route heads across the Glen valley via a viaduct towards the RaBT carpark, the Offline MTS Option veers west to join the remaining section of the forestry track and tie into the B828 Glen Mohr local road. The section of the B828 Glen Mohr local road from the forestry track junction to the A83 Trunk Road at the RaBT carpark will require to be upgraded to allow two-way working with priority given to the A83 Trunk Road traffic at the junction with the continuing B828 Glen Mohr local road. The Offline MTS option drawings are included as Appendix C of this report.