# 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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### Will car be able to fit in from this gate from front, as well as from rear?

The gate is 8 ft (96 inches) and the road is 10 ft (120 inches). I am not a engineer nor a professional . Help me calculate stuff, please.
2k 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 '...
672 views

1 vote
425 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 ...
3k 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 ...
130 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 ...
197 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 -- ...
1 vote
29 views

### 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 ? ...
676 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 ...
179 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 ...
367 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 ...
754 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 ...
5k views

### 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 ...
72 views

### 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 ...
1 vote
49 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 ...
2k 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 ...
263 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 ...
18k 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 ...
553 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, ...
103 views

### 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.
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 ...
477 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 ...