A system of two-way traffic using lanes of sub-standard width to provide two traffic lanes in each direction on a single three-lane carriageway was implemented during the reconstruction of a section of M6 motorway in 1976. Despite the reduced lane widths (2.75 metres for light vehicles, 3.35 metres for heavy vehicles), the capacity and journey-time/flow relations for the site did not differ appreciably from those for standard lanes. Even when the hard shoulder (which was in use as a traffic lane) failed locally under the weight of the heavy vehicles and the relative positions of the light and heavy vehicles were reversed to reduce the loading on the hard shoulder, the extra manoeuvres involved did not appear to affect the performance of the site. Overall, the delays averaged only 270 veh-h per day, and these would have been considerably higher if any other method of operation (segregated contra-flow or two-way operation with standard-width lanes) had been used. (Author/publisher)
Abstract