27

I think you are talking about roundabouts, not traffic circles. It is baffling to those of us in the UK that Americans think roundabouts are a new idea. In the UK we have so many variants, from mini-roundabouts all the way up to full motorway junctions (a giant roundabout above or below the motorway). So do roundabouts take up more space? Not necessarily, ...


18

This is very common misunderstanding. When we look a a road, we see few centimeters thick layer of bituminous surface, and we think about "the road" as "the asphalt/tarmac." It's not. When you look how a road is build (or rebuilt), you can see that "the road" is actually over half a meter (or more) deep, consists of layers of sand and gravel and has ...


18

source google maps The distance between the intersection and the rail is 100m, The road would need to rise about 10m to clear the track. This would mean a average grade of 10%. However you also need to account for the vertical curve in the road so the max grade would be quite a bit higher. The max grade allowed for non-local roads in the US is about 8% (...


14

There's a hierarchy of junctions, that you'll find in most standard highway design guides, such as the UK's immense Design Manual for Roads and Bridges. Different junction designs have different motor-vehicle capacities, and operate best at different speeds. Within towns and cities, junction capacity is critical: it is that that determines the network's ...


13

I'll give you some considerations that you may not be aware of. Also, take the disclaimer that I'm in the US (but construction is construction, right?) Frequently moving construction cones/barrels along the road is less efficient than setting them out once and only making minor adjustments to their location. Depending on the type of work being done, some ...


12

Spiral A spiral curve is a geometric feature that can be added on to a regular circular curve. The spiral provides a gradual transition from moving in a straight line to moving in a curve around a point (or vise-verse). The use of a spiral is about making the road or track follow the same form that the vehicle naturally takes. In a car, you don't go ...


11

Roundabout: Pros As you've mentioned, the Mythbusters' test results showed that roundabouts were about 20% more efficient for cars, good for high traffic Allows more cars to cross at a time. Doesn't need traffic lights. Safer Cons As you've also mentioned, it takes up more space. Uses more material to make. 4-way intersection Pros Easier for ...


9

It isn't a question of being "aesthetically pleasing to the eye", but rather of comfort. If you had a curve that was simply a circular arc, upon entering that curve, you would immediately feel a sideways centripedtal force that is proportional to your speed and inversely proportional to the radius of the curve. In other words, you would have to suddenly ...


9

Yes. Michigan left This page (pdf here) is very informative, though you really have to dig to get what you want. In a sub-section of 10.2.2 Median U-Turn Crossover, I found this (A "Michigan left" is referred to as a "median U-turn crossover"): A study on a Michigan corridor used simulation to compare median U-turn crossovers with two-way left-turn ...


9

The technical term for this (in the UK) is "deterrent paving" and its function is to discourage pedestrians, cyclists and drivers from being where they are not supposed to be. In the OP's photo, the paved area apparently is leading to a "dead end" which is divided from the roadway by a crash barrier - i.e. this is not a "footpath". From the photo on their ...


8

Like the British, Australia has had roundabouts for at least five decades in some shape or form and there prevalence has increased over the last thirty years or so. In the city were I live there is a five-way intersection and it is controlled by a single roundabout, nothing else. It's been operating for at least forty years without any issues. It's easier ...


8

You mean going back to cobblestone roads? Many sidewalks are often paved with pavers. One of the challenges is maintaining a level surface. Asphalt holds itself together like a sheet and a dip in the surface below will pull on the sides delaying the onset of potholes. while separate parts will start moving under the vibration and frost heaving. Once the ...


7

Asphalt, which is essentially crushed aggregate bound with bitumen has a lot of advantages for road building. It is porous and so can drain by allowing water to pass through it as well as running off the surface. Because it is made up of particles of crushed masonry it has good friction characteristics in all directions (ie you get the same grip turning ...


7

I think that there are a few things that you aren't considering. Subgrade Most roads have at least 12 in (300 mm) of compacted aggregate (rock) under the actual pavement. If the existing soil is very weak, then this depth of aggregate subbase can be increased. Sometimes the soil needs to be strengthened by mixing in cement. This means that just removing road ...


7

Yes, there would be a noticeable difference. Normal passenger cars don't really stress the road surface much. That's not so much the issue. As a analogy, you can have 100 people walk across a small plank, and it holds fine, but even 10 people on the plank at the same time will stress it to breaking. Cars in normal operation don't much hurt a normal road ...


7

This information comes from a design document by the Iowa DOT (US). It might not apply everywhere in the world, but the considerations are probably universal. For clarity, the amount of banking of a turn is typically called super elevation. At least in the US, this is given as a percentage for roadways. The maximum super elevation is 8%. The typical high-...


6

Roundabouts are only good for equal distribution of incoming traffic. As soon as one road feeds more traffic it will starve the other roads. Small roundabouts are less efficient than large ones. So to get an efficient roundabout you need some space to lay it. Mini's are only good to specify equal right of way to the roads in low traffic areas. Double lane ...


6

A wider road will have faster average traffic speeds, because faster vehicles will be hindered less by slow ones, with more lanes available for overtaking. So longer visibility distances are needed for safety, and hence more gradual curves and more gradual changes of gradient (no "hidden spots" over the brow of a hill, etc). Note, for most "fast" roads ...


5

The slope angle of such slopes is constructed to be less than the angle of repose for the material used in the slope. The angle of repose is the great angle to which granular materials can be dumped without slumping. The higher the cohesiveness of the material, the higher the angle of repose. Stability of such a slope will be improved by compacting the ...


5

There are a few methods that are used to control erosion before permanent vegetation is established. The exact method used can depend on location (also country), season, preference, governing laws, etc. Mulching This is almost always done. Mulch is frequently straw but can also be ground up newspaper. This helps to initially keep the soil from eroding while ...


5

Circular arcs are not used except in special situations, because the sudden change in curvature from a straight road to a circular arc would mean drivers had to quickly turn the steering wheel to the correct position to follow the circular arc, hold the wheel steady, and quickly turn back to straight at the end of the arc. There would also be problems if the ...


5

Roads are usually designed using catenary curves. https://sketchup.engineeringtoolbox.com/catenery-curve-c_169.html Road curves are designed around vehicle velocities and they are not uniform. As vehicles approach a curve they tend to slow down and then accelerate out of the bend which means a non uniform curve is best suited to the purpose. This can be ...


4

They lay turf pads down to kickstart the grass coverage. Even the loose pads will have better erosion protection than bare soil. Other options include laying down a sheet with holes for plants/shrubery to grow through, the sheet will let enough rain through to let the plants grow but prevent the hillside from eroding until the planted shrubs are robust ...


4

As some of the other posters have mentioned a road has several built up layers (hopefully). The drainage system is usually very important. Bad quality roads are usually because the drainage is poor or non-existent. Roman roads were sometimes as much as 10 feet thick, which is why many are still in use today, 2000 years later. It is possible to create a ...


4

A round-a-bout introduces a disruption in any traffic, no matter which direction. In your case the only two "collision" directions - two left turns - are the least used ones, so traffic lights working in a preference program with induction loops on the two possible left turns, plus uncontrolled right turn lanes would be optimal. The crossing would stay in ...


4

People using the road make mistakes (like running stop signs and red lights), always have and always will. Crashes will always be with us, but they need not result in fatalities or serious injury. Modern roundabouts are the safest form of intersection in the world - the intersection type with the lowest risk of fatal or serious injury crashes - (much more ...


4

The US Federal Highway Administration says: Effective noise barriers can reduce noise levels by 10 to 15 decibels, cutting the loudness of traffic noise in half. It goes on to say that a 5 dB reduction is simple to obtain and a 20 dB reduction is nearly impossible to obtain. Even completely burying a highway does not eliminate the noise. While not a ...


4

Vertical loading does (almost) nothing to a properly designed and constructed bitumen road surface, it is horizontal loading that causes deterioration. Horizontal loading comes from acceleration, braking and turning. For acceleration and braking speed is unimportant, it is only the rate of change of speed that matters. For turning, speed can in theory make ...


4

Public roads must be safe to handle slow, heavy traffic and be safe to pull over a stalled car under a snow storm. They should be flat enough to make it easy for emergency services such as ambulances, firemen to set up a triage and evacuate or help injured people out. There are standards for road curves and turns and maximum slopes both uphill and sideways,...


4

I wouldn't expect this to be a big problem. Would you be worried about leaving a car parked in one place on this pavement for a month? Typical car tire pressures are at least 2 bar or 200 kN/m^2, about twice as high as your cabin. Note, the weight of the car is almost entirely supported by the air pressure in the tires, so the pressure on the pavement ...


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