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 ...
- 6,101
10
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 ...
- 12.5k
7
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 ...
- 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.
...
- 51
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 ...
- 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 ...
- 982
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 ...
- 22.6k
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 ...
- 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,...
- 22.6k
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, ...
- 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 ...
- 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'...
- 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. ...
- 6,101
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 ...
- 15.2k
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 ...
- 15.2k
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 ...
- 6,115
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 ...
- 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 ...
- 8,197
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 ...
- 8,197
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 ...
- 982
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 ...
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).
- 31
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 ...
- 303
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,...
- 747
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 ...
- 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, ...
- 298
2
votes
Accepted
What is the entirety of breadth of road called?
A number of online sources use the term road reserve to encompass the road, associated infrastructure, such as drainage and spare land for additional lanes in the future. The width of this would be ...
- 9,712
2
votes
Why was a coil chosen over a straight for this overbridge?
In 1909, the same thing was done twice on the Canadian Pacific Railway rail line through Kicking Horse Pass in the Rocky Mountains:
Two circular tunnels (dashed white lines) were dug into the ...
- 789
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 - ...
- 303
2
votes
NASCAR corners on public roads
The banking on speedways are designed for speeds in excess of one hundred miles per hour (160 kmh) and cannot maintain a vehicle position at speeds below a certain level. For ordinary traffic speeds, ...
- 7,297
Only top scored, non community-wiki answers of a minimum length are eligible