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Questions tagged [highway-engineering]

Highway engineering covers the design of highways, in particular: layout (vertical and horizontal), surfacing design and drainage

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What kind of splines should be used when planning roads?

I would like to plan a small road network for an imaginary city, and I am looking for a way to create curved road segments. I am familiar with cubic Bezier curves, but I am not sure if it's the best ...
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0answers
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Bills of Quantities for Highway Works (UK) [closed]

Does anyone know a software/tool, which allows creating Bill of Quantities in accordance with Manual of Contract Documents for Highway Works (UK)? In particular, I am interested in working with the ...
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2answers
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How do enginners build highway interchanges ? Are highway interchanges build based on a mathematical theory such as braids and knots theory?

I am trying to find how do enginners build roads especially highway interchanges. Are they relying on any topology theories such as braids and knots theory? Is there any connection or link between ...
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Why was a coil chosen over a straight for this overbridge?

I saw this meme on Facebook showing a coiled railway overbridge and an alternative plan. I replied that straightening that overbridge will force it to start at the other side of the road, and you need ...
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1answer
80 views

What's sort of “sidewalk” pavement is this?

I was recently walking down a road when a car came my way (I'm an inveterate jaywalker). I moved over to the sidewalk, only to notice it clearly wasn't a sidewalk at all. The pavement looked like this:...
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2answers
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Why are roads straightened when widened?

When widening a road, why does construction seem to inevitably include a "smoothing" out of the curves on the road, essentially making it more straight? I've seen this personally on roads where I ...
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1answer
57 views

Street Light Arrangement Method

Hello I am a high school student and I am curious about how street light is arranged along the road. Is there government laws to install street light on the road or is the arangement of the street ...
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0answers
34 views

Are there any turborotonde / turboplein designs with more than four exits?

For an at-grade intersection of multi-lane roads, the "Turborotonde" (Dutch language Wikipedia article) or "Turboplein" (Dutch language wegenwiki article) is an alternative to the multi-lane ...
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1answer
73 views

For an at-grade intersection of multi-lane roads, what are the (dis)advantages of a “turborotonde” or “turboplein” compared to a classical roundabout?

For an at-grade intersection of multi-lane roads, the "Turborotonde" (Dutch language Wikipedia article) or "Turboplein" (Dutch language wegenwiki article) is an alternative to the multi-lane ...
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0answers
67 views

How to define the Clothoid Constant in Clothodial Arc ( Spiral Curve)?

Referring to the document here on IfcClothoidalArcSegment2D, we have ClothoidConstant, which is defined as The constant $A$ (not $A^2$), that determines the ...
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2answers
58 views

What is the entirety of breadth of road called?

As roadway consists of a width of road on which a vehicle is not restricted by any physical barriers or separation to move laterally source, what is a similar term which encompasses the width of the ...
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Pavement stage construction; reduction of Structual Properties

Which properties of flexible pavement layers are reduced (discounted) in a stage construction design with an overlayed layer? Thickness of stage 1 Layers? Structural Number ? Modulus of Resilience ? ...
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2answers
99 views

How to calculate stopping distance with grade?

$$d = \dfrac{V_1^2-V_2^2}{2g\left(\dfrac{a}{g}\pm G\right)}$$ I am wondering if the car travel on the road of a sag curve or crest curve, there is two gradients of the curve. (G1, G2). Which gradient ...
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6answers
356 views

Does the speed of Heavy Vehicles make more potholes

Should Heavy Trucks drive more slowly on weak (bitumen) roads to reduce potholes in the road surface? I am discussing with a feasibility engineer what causes more potholes. He says it is simply the '...
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1answer
105 views

What should a road's traffic volume to justify the number of lanes?

Is there a standard that transportation engineers use for the number of vehicles a road should carry daily for it to be widened to four, six, eight lanes, etc? Curious because I've noticed that some ...
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1answer
80 views

What are the disadvantages of free-flow intersections?

I've recently learned about free-flow intersections. In particular, the DCMI, and the Stack interchanges. What are the disadvantages of using them, compared to the "normal" signaled intersections? do ...
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1answer
126 views

How can traffic signal controllers handle multiple conflicting preemption requests of equal priority without dropping one?

Let us assume that we are North American traffic engineers, and have the (hypothetical, plausible, yet pathological) intersection configuration depicted (not to scale and lacking lane lines, sorry -- ...
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1answer
206 views

How much noise does a road noise barrier block?

I am from The Netherlands, where noise barriers like these are commonly built along motorways: Now I live in England, where such structures are almost non-existent. In The Netherlands, living 200 ...
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0answers
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How is a merge left or a merge right chosen?

Recently a certain 2 lane exit ramp changed from merge right to merge left, but the entrance ramp immediately preceding it is merge right. Why was this changed? In a given circumstance, what dictates ...
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0answers
36 views

Are there standards or guidance for the placement and location of rest areas on newly constructed or designated U.S. Interstates?

As the highway engineers here may already know, U.S. highway 71 through most of Missouri was recently redesignated as a section of Interstate 49 after the completion of grade separation work at ...
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3answers
205 views

Why do North American Roadways Use Yellow Instead of White to Separate Opposing Traffic?

For those of us in the US, we're used to seeing roadways with yellow stripes separating traffic traveling against our direction of travel, and white stripes separating traffic traveling in the same ...
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2answers
127 views

How do you call the intersection with barrier and you can always right turn?

In the photo above I can name the first 3 intersection a) Regular intersection b) T intersection c) Skewed intersection I am having a hard time on identifying the fourth intersection, what do you ...
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1answer
114 views

What would be the implications of a metal highway design? [closed]

I'm an engineering enthusiast but I don't yet have a formal education in engineering and I'm hoping you guys can tell me about the implications of using a metal road design in terms of durability and ...
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2answers
395 views

What is the justification for working on such large stretches of road?

I live and work in the UK, a country known for relentless roadworks. Last week I drove through roadworks on the M1 that lasted for 18 miles, necessitating road users driving at 50 mph. Of course, ...
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3answers
640 views

How are earthfills not eroded before they are overgrown with grass?

Almost every railroad and vehicle road landfill has its slopes overgrown with grass which is quite good at preventing erosion. However it takes some time (a year or more) for the grass to grow and ...
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7answers
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Why do we pave roads instead of making them from removable parts?

If roads were made of removable parts, we'd probably have fiber cable internet everywhere by now I'd say. It'd be so much easier to install e.g. new electricity and water infrastructure and to ...
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0answers
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Effect on pavement by light tracked vehicles with rubber inserts

Is there data available to quantify the effect on pavement by light tracked vehicles with rubber inserts. One example of such a vehicle is the M113 armored personnel carriers shown below.
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1answer
2k views

Does passenger car traffic actually damage roads?

Pavement Design In roadway pavement design, the (US) controlling design load is usually the Equivalent Single Axle Load (ESAL). This number attempts to quantify how much bending stress a given ...
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1answer
2k views

How are maximum speed limits determined for banked curves?

I was once told that the speed limits on banked highway curves (specifically off-ramps) were determined by assuming zero friction between the car and the road, such that as long as you stayed on the ...
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3answers
10k views

What is a Spiral Curve, and How is it Different from a Normal Curve?

I've heard the term spiral curve used to describe a section of highway that is more aesthetically pleasing to the driver's eye. However, I believe I've driven on enough road to say that I can't ...
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1answer
299 views

When are Single Point Urban Interchanges used?

There is a topic discussing the pros and cons of roundabouts. A less common intersection is the Single Point Urban Interchange (SPUI). This is an intersection that seems to be mostly used on ...
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1answer
213 views

Best traffic control device/system for given situation

I am familiar with the round-a-bout/traffic light pros and cons, however, I've been tasked with deciding on a solution for the given parameters below. Currently, there is a two-way (four lane) road ...
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1answer
151 views

Has a specific type of alternative intersection been shown to reduce congestion & accidents?

Localities in the US have different road layout and setups. For example the Michigan Left, Jersey Left/Jug Handle, vs a standard 4 way stop with left turns at the intersection. Have any of them come ...
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12answers
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What are the pros and cons of a traffic circle versus a traffic light intersection?

The debate of traffic circles (also called roundabouts or rotaries) versus traffic light intersections has been in progress for a while. Those in favor of traffic circles say that, among other things, ...