A Simulator Based Evaluation of Speed Reduction Measures for Rural Arterial Roads

In Great Britain accident rates on rural roads are not falling as fast as those on urban roads. In 1993 the number of casualties from accidents on rural A roads was 4% higher than the average for 1981-85, which is the baseline for the Department of Transport target of a one third reduction in road accident casualties by the year 2000. Driving too fast for the conditions is a major factor in accident causation. High speeds in conjunction with the varying geometric conditions common on rural single-carriageway A roads, result in a fatal accident rate which is higher than that for any other type of road. The aim of the research was to investigate, in a safe and controlled manner using the University of Leeds Advanced Driving Simulator, the effectiveness of a variety of measures for reducing driver speeds on rural single-carriageway arterial roads, in order to identify practical and cost-effective combinations of treatments to reduce both the frequency and severity of accidents on such roads. Treatments appropriate to each of three situations were investigated. These were: (1) treatments that reduce speed and speed variance on fairly straight roads (general treatments); (2) treatments that reduce curve entry speeds for sharp bends; (3) treatments that reduce speeds on the approach to and through villages. Treatments investigated included the use of road markings to reduce lane width or produce horizontal deflection; the use of signs both on posts and on the road surface; and the use of optical illusions to affect the driver's perception of speed or road width. Many of the treatments have been used previously, but few have been evaluated in a controlled way. The first phase of the research involved the evaluation of each individual treatment. The treatments were evaluated with respect to their effect on speed, vehicle lateral position, and incidence of overtaking. The second phase of the research involved the evaluation of variations on and combinations of the most effective treatments. Substantial reductions in speeds were obtained by some of the treatments evaluated, for all three situations studied. There were also reductions in speed variance. These reductions are significant both in statistical and practical road safety terms. For the village situation the most effective combination of treatments was the chicane without hatching, yellow or white transverse lines throughout the village, and countdown speed limit signs on the approach to the village. For the bend treatments the most effective treatments were transverse lines with reducing spacing (including a central area filled with transverse lines); a central hatched area; a Wundt illusion (a series of chevrons with increasing angles but constant spacing, pointing towards the driver); and hatched areas at the edges of the road. Further speed reductions may be produced by combining one of the above treatments with the most effective sign treatments — SLOW or a triangular, warning sign style, advisory speed sign painted on the road surface. For the general treatments all those which involved lane narrowing produced speeds significantly different from the control. Shoulders delineated by continuous lines were more effective, than those delineated by broken lines. Shoulder width was not important, but carriageway width was. For central hatching, type of delineation and width of hatched area was not important. The location (central/edge) and type (removing carriageway or lane space) of the narrowing was not important

Correction to: An autosomal dominant neurological disorder caused by de novo variants in FAR1 resulting in uncontrolled synthesis of ether lipids (Genetics in Medicine, (2021), 23, 4, (740-750), 10.1038/s41436-020-01027-3)

In the original author list, Seth Perlman’s degrees were listed as MD, PhD. Dr Perlman’s degree is MD. The original version has been corrected

An autosomal dominant neurological disorder caused by de novo variants in FAR1 resulting in uncontrolled synthesis of ether lipids

Purpose: In this study we investigate the disease etiology in 12 patients with de novo variants in FAR1 all resulting in an amino acid change at position 480 (p.Arg480Cys/His/Leu). Methods: Following next-generation sequencing and clinical phenotyping, functional characterization was performed in patients’ fibroblasts using FAR1 enzyme analysis, FAR1 immunoblotting/immunofluorescence, and lipidomics. Results: All patients had spastic paraparesis and bilateral congenital/juvenile cataracts, in most combined with speech and gross motor developmental delay and truncal hypotonia. FAR1 deficiency caused by biallelic variants results in defective ether lipid synthesis and plasmalogen deficiency. In contrast, patients’ fibroblasts with the de novo FAR1 variants showed elevated plasmalogen levels. Further functional studies in fibroblasts showed that these variants cause a disruption of the plasmalogen-dependent feedback regulation of FAR1 protein levels leading to uncontrolled ether lipid production. Conclusion: Heterozygous de novo variants affecting the Arg480 residue of FAR1 lead to an autosomal dominant disorder with a different disease mechanism than that of recessive FAR1 deficiency and a diametrically opposed biochemical phenotype. Our findings show that for patients with spastic paraparesis and bilateral cataracts, FAR1 should be considered as a candidate gene and added to gene panels for hereditary spastic paraplegia, cerebral palsy, and juvenile cataracts