Two-lane rural roads

MAY 03] Mayora J.M.P., Rubio R.L., Relevant variables for crash rate prediction in Spain s two lane, rural roads . Proceedings of the 82nd Transportation Research Board Annual Meeting, Washington DC, USA, 2003. 

The aim is to illirstrate how the speed distribution and other measures (e.g. mean speed) can be changed on roads where the speed limit is lowered, not to estimate the total effect on the network. Therefore, on roads where the speed limit was decreased from 110 to 100 km/h, the 8 sites with the greatest speed reduction (of a total of 20 sites) were selected The measurements are from 2 + 1 roads (i.e. continuous three-lane roads with altematiug passing lanes and the two directions of travel separated by a flush divider with a median barrier) and standard two-lane rural roads. At each measirrement site, the measurements were made both before (August 2008) and one year after (August, 2009) the new speed limit was instituted. To be considered an acceptable measurement, the speed at each road site had to be measured for at least... 

CAP 07] Cafiso S., La cava G., Montella A., Safety index for evaluation of two-lane rural roads . Transportation Research Record. Journal of Transportation Research Board, no. 2019, TRB of the National Academies, Washington D.C., pp. 136-145, 2007. 

Local government units have jurisdiction over approximately 75 percent of the public highway mileage in the United States. Ownership of two-lane rural roads is even more highly concentrated with local governments. State DOTs have responsibility and control over only a fraction of the facihties with the highest crash rates. Yet states can substantially influence local transportation efforts. 

All agencies evaluate and selectively include countermeasures in resurfacing projects to reduce the frequency and severity of run-off-road crashes, which are overrepresented on two-lane rural roads. The following strategies were observed during the scan ... 

Reflective pavement markings provide drivers with improved visual guidance, but may also result in behavioural adaptation. For example, Mullowney (1982) studied the effect of reflective pavement markers on traffic speed on two-lane rural curves. He concluded that the markers caused vehicles to demonstrate a smoother speed profile through the curved road sections, which resulted in less abrupt speed changes, which was attributed to earlier deceleration. However, vehicle speeds were observed to increase at the apex of the curve, which again may have been due to the behavioural adaptation in the form of increased driver confidence due to the improved view of the curve geometry. 

Development of Safety Performance Functions for Two-Lane Rural First-Class Main Roads in Hungary... 

In the framework of the European project Identification of Hazard Locations and Ranking of Measures to Improve Safety on Local Rural Roads (lASP), a new surrogate safety measure, the safety Risk Index (RI), was defined to supplement crash investigation studies in the safety evalnation of two-lane rural highways, by using data from Sis and design consistency models [CAF 07],... 

Gross, F., R Jovanis, and K. Eccles, Safety Effectiveness of Lane and Shoulder Width Combinations on Rural, Two-Lane, Undivided Roads, Presented at 88th Annual Meeting of the Transportation Research Board, Jan. 11-15,2009. 

The crash occurred on a section of local road near her hometown, a section with which she was very familiar. It was a typical two-lane, two-way rural road and was part of a route Abbey had driven frequently with her father while she was a learner driver acquiring the 120 hours of supervised experience required before a Victorian learner can apply for a provisional driving licence. Her parents had been conscientious in ensuring that she logged her quota of hours under a variety of driving conditions. 

On rural two-lane roads there are safety advantages in achieving a minimum lane width of 3.65 m. 

Most rural injury accidents occur on A roads (53%) on two-lane roads (91%) in 60mph speed limits (97%) and away from junctions (65%). One in 20 rural accidents occur at private drives. 

But let us then look at rural two-lane roads, which in many countries have an 80 km/h, or even 100 km/h, speed limit (see Figure 22.5). If a crash were to occur under these conditions, the outcome would almost certainly be serious. It is clear that contemporary vehicle design will not be able to withstand real crash conditions on rural roads as long as we accept road layouts as they are today (i.e., having no separation of driving directions) and travel speeds which exceed the frontal crash test speeds. Even in situations where it is possible for drivers to slow the vehicle before a crash occurs, crash speed is likely to result in forces that are unsurvivable. 

A famous example of a measure which fits within Vision Zero perfectly well is the design of rural roads in Sweden with 2 -i-1 lanes and a mid-barrier, also known in Sweden as collision-free roads (Figure 22.10). The two directions are physically separated, often by cable barriers. This cross-section design is appropriate for Swedish conditions because a straightforward motorway design, a solution used in many countries, is not necessary from a capacity point of view. Furthermore, Sweden has a tradition of building wide rural roads (13 m, with two traffic lanes and two hard shoulders) which can easily be redesigned into a 2 -i-1 cross-section. In addition, side... 

Persaud, B. N., R. A. Retting and C. A. Lyon (2004). Crash reduction following installation of centerline rumble strips on rural two-lane roads. Accid. Anal Prev., 36,1073-1079. 

Paving shoulders on rural two-lane roads in Australia 2.8... 

The review of the states design manuals on 3R revealed considerable variation for these two cross-section elements, not so much in the actual widths but in the conditions. Some states have one value for aU road types and conditions, whereas several others have values that vary by ADT, speed, urban vs. rural, and road type. Vermont is an example of a state that has minimum values for lane and shoulder width that vary by ADT, rural vs. urban location, and NHS vs. non-NHS fedlity. Table 13 shows their values. In addition, Vermont s guidelines state that aU shoulder widths should be reviewed for accommodation of bicycle and pedestrian traffic according to its Pedestrian and Bicycle Facility Planning and Design Manual. 

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