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Engineering Stack Exchange

Questions tagged [traffic-intersections]

13 questions
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How are train crossing signals and highway traffic signals coordinated?

Some roadway intersections that are near railroad tracks have signs that light up when a train is approaching. These signs warn that certain turns are not allowed because of the train. One of these signs is shown below from the City of Edmonton. My…
hazzey
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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 with a speed limit of 35 mph. Rough traffic counts…
Anthony Burleson
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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 overpasses. What makes this intersection unique is that…
hazzey
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What is the starting/stopping sequence of a traffic light

As is probably known a traffic light may be turned off in which case normal rules applies to the intersection. While the traffic light is active then red & red+yellow means that drivers are required to stop, while green means that the drivers are…
skyking
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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 call that one?
Cary Bondoc
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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 -- I did not have time to build the model to scale…
ThreePhaseEel
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What's the purpose of a 'burger' lane in a roundabout?

I recently read about a newly proposed 'burger' lane across a roundabout. From what I can see, it bypasses the main point of a roundabout, a continuous circle of traffic with well defined rights of way. The only reason I can imagine one is to stop…
AncientSwordRage
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Historically, how did tram switches work?

Historically, the switches on regular railways were switched manually using a lever by dedicated staff to route trains correctly before getting replaced by an automatic electronic system. A similar system is in place for trams in modern times, but…
user6892
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"Burger" lanes: What are they, where are they found, and what do they look like?

What and where are they, and what do they look like? Do all transportations with roundabouts use them in some form? This is different from What's the purpose of a 'burger' lane in a roundabout?, which is very specific to why. This is an open floor…
Tony N
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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 fit for this problem, and it's not trivial to…
Iter Ator
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Specific Questions about Traffic Signal Preemption at Grade Crossings

Several questions, regarding traffic signal preemption at a grade crossing Is the preempt relay, which triggers the preemption sequence, located inside the bungalow which houses the grade crossing predictor, or is it located inside the cabinet…
alx19881
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Need help identifying this three-layer diverging diamond-style interchange

I'm an avid fan of Cities: Skylines, and it has occurred to me that one of the types of interchanges that seems to fare very well with the simulated traffic is this three-layer diverging diamond (style) interchange. I realize this isn't a true DDI,…
brandonscript
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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 they cost significantly more?
mbrg
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