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18 votes
Accepted

Why was a coil chosen over a straight for this overbridge?

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 ...
ratchet freak's user avatar
9 votes
Accepted

What's sort of "sidewalk" pavement is this?

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 ...
alephzero's user avatar
  • 12.5k
7 votes
Accepted

What would be the implications of a metal highway design?

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 ...
Chris Johns's user avatar
  • 15.2k
6 votes
Accepted

Why are roads straightened when widened?

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 ...
alephzero's user avatar
  • 12.5k
5 votes

What are the pros and cons of a traffic circle versus a traffic light intersection?

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. ...
Scott Batson's user avatar
5 votes

What kind of splines should be used when planning roads?

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 ...
alephzero's user avatar
  • 12.5k
5 votes

What kind of splines should be used when planning roads?

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 ...
Rhodie's user avatar
  • 974
5 votes

Why are expansion joints on prestressed concrete box girder bridges sometimes not located directly above the bridge piers?

Because the extension of the longer span past the column into a cantilever allows it to enjoy the benefit of the cantilever part's positive moment effect on the reduction of the midspan negative ...
kamran's user avatar
  • 22.4k
4 votes

How much noise does a road noise barrier block?

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 ...
StrongBad's user avatar
  • 151
4 votes
Accepted

NASCAR corners on public roads

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,...
kamran's user avatar
  • 22.4k
4 votes
Accepted

Permanent uneven deformation of asphalt car park under portable cabins

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, ...
alephzero's user avatar
  • 12.5k
3 votes

What is the entirety of breadth of road called?

In the US this is commonly referred to as the Right-of-Way (property line to property line on either side of the roadway). Or, if the roadway right-of-way is wider than needed for construction, it may ...
MacsAre1's user avatar
  • 171
3 votes

Does the speed of Heavy Vehicles make more potholes

If you have a 20 ton truck sitting stationary on the road, it's exerting 20 tons of force on the roadway. If that truck is traveling at 100km/hr, it is still exerting 20 tons of force on the road. I'...
JPhi1618's user avatar
  • 133
3 votes

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

"Vehicles per day" is a pretty bad metric to use. Instead you should look at rush hour and see how many vehicles are trying to get through. Every lane can carry 1800 vehicles each hour on a freeway. ...
ratchet freak's user avatar
3 votes

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

As mentioned there are relatively few situations in the UK where this would apply as multi-lane roads tend to have central barriers or other distinctive features. There is also a system of coloured ...
Chris Johns's user avatar
  • 15.2k
3 votes

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

In UK terminology, your separate turning lane would be called a "filter lane" ( see e.g. Collins dictionary definition). This definition doesn't mean that you can always turn in that lane, it means ...
AndyT's user avatar
  • 3,143
3 votes

Why do we pave roads instead of making them from removable parts?

Other answers have well described a road is a lot more than just the surface layer and the vast majority of the cost is the planning and logistics involved rather than the actual materials. Current ...
Chris Johns's user avatar
  • 15.2k
3 votes

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

Q: ...how one can determine if a section of curve on a highway is classified as a "spiral" curve, and are there other advantages besides "making it look good"? A: The purpose of a spiral or ...
Greying_Geezer's user avatar
3 votes

How do enginners build highway interchanges ? Are highway interchanges build based on a mathematical theory such as braids and knots theory?

It's much closer to graph theory. First, traffic projections: basing on known and projected urban data - habitation, production, recreation, trade zones, transit, etc, the general transition patterns ...
SF.'s user avatar
  • 6,105
3 votes

Banking progression in NASCAR tracks

In highway design, this is called a superelevation and spiral transition: https://en.wikipedia.org/wiki/Track_transition_curve The length of the spiral is based upon the design speed. For USA highway ...
DavidJ's user avatar
  • 154
3 votes

formula for super elevation

The equation for highway superelevation is $$e + f = \dfrac{V^2}{gR}$$ where: $e$ is the rate of superelevation in %, $f$, the friction coefficient of the pavement, $V$, the velocity, $g$, the ...
r13's user avatar
  • 8,184
3 votes

Why have they stopped having curbs on streets?

On the following roads, a curb is not desirable - highway without pedestrian traffic, rural highway (ease of pulling to the shoulder and not to restrict water flow to ditches), City streets designated ...
r13's user avatar
  • 8,184
2 votes

What are the pros and cons of a traffic circle versus a traffic light intersection?

Roundabouts let traffic flow more smoothly and there is also less reliance on technology that can malfunction due to a series of factors (i.e. power outage, etc).
Ethan's user avatar
  • 31
2 votes

What are the pros and cons of a traffic circle versus a traffic light intersection?

In any design regarding public traffic your biggest problem is going to be managing the human factors of competence, confidence and error. The entire purpose of traffic management is to control human ...
Rhodie's user avatar
  • 974
2 votes

What are the pros and cons of a traffic circle versus a traffic light intersection?

Something that I didn't see mentioned here is a HUGE saving in wasted fuel, burnt by cars and truck sitting at a traditional intersection, waiting for a light to change. To me, this is the best ...
Roger Williams's user avatar
2 votes

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

This is probably an example of a channelized intersection, where you have right turn bays that split from the main road just before the intersection: References: Individual Movement Treatments - ...
gate_engineer's user avatar
2 votes
Accepted

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

The most likely reason yellow is used as a color was probably the result of standardization efforts between the 1960s and 1970s (NCHRP Report 484, p8). Since the United States is a very influential ...
gate_engineer's user avatar
2 votes

Does the speed of Heavy Vehicles make more potholes

For what its worth our (Asutralian) asphalt test tracks fail by weathering because they don't get enough traffic. Water seeps in among the stones and spoils the bond between the bitumen and the stones,...
Greg Locock's user avatar
2 votes

Does the speed of Heavy Vehicles make more potholes

Bitumen is a viscoelastic material and the time/duration that force is exerted on it is directly proportional to the fatigue of the material. Simply put, low speed causes more damage to the bitumen ...
Anshul's user avatar
  • 21
2 votes

Does the speed of Heavy Vehicles make more potholes

To answer this question, you need to consider the failure modes you are protecting against. To understand the failure modes, you need to have the full details related to the materials of the road, ...
Isa's user avatar
  • 298

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