5 ms·

Get rid of most traffic lights. Use well-designed roundabouts.

by dalke 11y ago

protomyth 11y ago
How much would that cost?
- dalke 11y ago
  Depends on many factors, including how much you value human life. Quoting from http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_672.pdf http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_672.pdf : > The initial design and construction cost of a roundabout can vary significantly depending on the roundabout size, right-of-way impacts, illumination requirements, and other design or aesthetic features that may be desired. A new single-lane roundabout intersection in an unbuilt environment can have construction costs comparable to a traffic signal. However, as the size of the roundabout increases, particularly in a fully built-out commercial or residential area, the cost of roundabout construction can be higher than that of a traffic signal, depending on the footprint of the roundabout relative to that needed for the signal. However, the ongoing operations and maintenance cost of a roundabout can be less than that for a signal, with the possible exception of increased illumination needs for a roundabout. Although the initial construction cost may be more, a roundabout can have less operating and maintenance costs than a traffic signal, and the service life of a roundabout is significantly longer, approximately 25 years, compared with 10 years for a typical signal (2). Roundabouts also provide substantial cost savings to society due to the reduction in crashes, particularly fatal and injury crashes, over their service life. It also depends on how much you value people's time waiting for a light to change, as described in the parent scenario.
  - protomyth 11y ago
    I guess I didn't phrase my question correctly, how much would it cost to replace all the traffic signals with roundabouts (per your original statement)? I am betting that would be cost prohibitive much less concerns for space.
    - dalke 11y ago
      I didn't say "all", I said "most". Even countries with roundabouts also have traffic signals. My comment was not trying to establish what you are asking for. Instead, I was pointing out that there are many factors in addition to "cost to replace". There is also the yearly upkeep costs (power to the light, landscaping), signal timing maintenance every few years, and a shorter lifespan for signals vs. roundabout. Plus, of course, the savings in human time and lives. Then there's systemic issues which are harder to quantify. Roundabouts have higher throughput than signals, so switching to a roundabout might reduce the need to widen nearby parallel roads, which is an indirect cost savings. And roundabouts without signals work even when the power goes out. Quoting from http://www.roundaboutresources.org/when-should-roundabouts-replace-traffic-signals.html http://www.roundaboutresources.org/when-should-roundabouts-r... : > Roundabouts give superior traffic and safety performance to signalized intersections and to cross intersections almost everywhere, but roundabouts cost more, and not every signalized intersection or cross intersection is in great need of correction. Therefore, a highway agency should start at the top of its high-crash list and its high-congestion list and work down, often converting the problem location into an offset intersection where crossing flows are not too high. ... > The modern roundabout should be recommended not only as a retrofit where there are present safety and capacity problems, but also as an intersection in new construction where roads join or cross each other for the first time. That seems eminently reasonable to me. Recall too that the challenge was to "devise a traffic light that would not be monumentally inefficient and incompetent", so the question is, how much would that hypothetical system cost per intersection, vs. a known, good solution to the given problem?
      - WalterBright 11y ago
        > much would that hypothetical system cost per intersection, vs. a known, good solution to the given problem? Since the lights already exist, as well as cameras, and network connections, the incremental cost would be a box with a computer in it. The development cost of the software would be amortized over tens of thousands of intersections.
        dalke 11y ago

Get rid of most traffic lights. Use well-designed roundabouts.

by dalke 11y ago

Get rid of most traffic lights. Use well-designed roundabouts.

protomyth 11y ago

How much would that cost?

dalke 11y ago
Depends on many factors, including how much you value human life. Quoting from http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_672.pdf http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_672.pdf : > The initial design and construction cost of a roundabout can vary significantly depending on the roundabout size, right-of-way impacts, illumination requirements, and other design or aesthetic features that may be desired. A new single-lane roundabout intersection in an unbuilt environment can have construction costs comparable to a traffic signal. However, as the size of the roundabout increases, particularly in a fully built-out commercial or residential area, the cost of roundabout construction can be higher than that of a traffic signal, depending on the footprint of the roundabout relative to that needed for the signal. However, the ongoing operations and maintenance cost of a roundabout can be less than that for a signal, with the possible exception of increased illumination needs for a roundabout. Although the initial construction cost may be more, a roundabout can have less operating and maintenance costs than a traffic signal, and the service life of a roundabout is significantly longer, approximately 25 years, compared with 10 years for a typical signal (2). Roundabouts also provide substantial cost savings to society due to the reduction in crashes, particularly fatal and injury crashes, over their service life. It also depends on how much you value people's time waiting for a light to change, as described in the parent scenario.
- protomyth 11y ago
  I guess I didn't phrase my question correctly, how much would it cost to replace all the traffic signals with roundabouts (per your original statement)? I am betting that would be cost prohibitive much less concerns for space.
  - dalke 11y ago
    I didn't say "all", I said "most". Even countries with roundabouts also have traffic signals. My comment was not trying to establish what you are asking for. Instead, I was pointing out that there are many factors in addition to "cost to replace". There is also the yearly upkeep costs (power to the light, landscaping), signal timing maintenance every few years, and a shorter lifespan for signals vs. roundabout. Plus, of course, the savings in human time and lives. Then there's systemic issues which are harder to quantify. Roundabouts have higher throughput than signals, so switching to a roundabout might reduce the need to widen nearby parallel roads, which is an indirect cost savings. And roundabouts without signals work even when the power goes out. Quoting from http://www.roundaboutresources.org/when-should-roundabouts-replace-traffic-signals.html http://www.roundaboutresources.org/when-should-roundabouts-r... : > Roundabouts give superior traffic and safety performance to signalized intersections and to cross intersections almost everywhere, but roundabouts cost more, and not every signalized intersection or cross intersection is in great need of correction. Therefore, a highway agency should start at the top of its high-crash list and its high-congestion list and work down, often converting the problem location into an offset intersection where crossing flows are not too high. ... > The modern roundabout should be recommended not only as a retrofit where there are present safety and capacity problems, but also as an intersection in new construction where roads join or cross each other for the first time. That seems eminently reasonable to me. Recall too that the challenge was to "devise a traffic light that would not be monumentally inefficient and incompetent", so the question is, how much would that hypothetical system cost per intersection, vs. a known, good solution to the given problem?
    - WalterBright 11y ago
      > much would that hypothetical system cost per intersection, vs. a known, good solution to the given problem? Since the lights already exist, as well as cameras, and network connections, the incremental cost would be a box with a computer in it. The development cost of the software would be amortized over tens of thousands of intersections.
      - dalke 11y ago