| Authors: | Alena Katharina Høye, Ingeborg Storesund Hesjevoll |
| Report nr: | 1909/2022 |
| ISBN (digital version): | 978-82-480-1965-7 |
| Language: | Norwegian |
| Attachments | Summary Full report - in Norwegian only Sammendrag |
By-pass lanes at a T-junctions consist of a widened through lane on the main road to allow through traffic to pass waiting left-turning vehicles in the presence of oncoming traffic.
By-pass lanes can under certain conditions be used instead of left-turn lanes. Among countries using by-pass lanes are Norway, Finland, USA, Denmark, and Australia. How by-pass lanes affect safety varies between studies. International studies found mostly crash reductions. Analyses of Norwegian crash data indicate unchanged or increased crash numbers at T-junctions where by-pass lanes were installed. Conditions under which by-pass lanes may be an acceptable alternative to left-turn lanes are, according to the Norwegian studies: (a) Traffic volume above 3000, speed limit 50 km/t or higher; (b) Many through vehicles pass waiting left-turning vehicles on the right side; (c) By-pass lane harmonizes with the roads curvature and sight conditions; (d) Not exceptionally many head-on collisions.
