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Edinburgh and “traffic flow”

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  1. chdot
    Admin

    ‘We’ have long complained about traffic engineers’ apparent obsession with TF. I despair when politicians go along with the need for/desirability of ‘improving’ TF.

    Somehow it’s a ‘given’, a ‘desirable objective’, or something.

    The downsides include road designs to facilitate this and (often) disadvantages to people on bikes. More noticeably, significant delays to people wanting to cross roads.

    I had naively assumed there might have been some reassessment. Don’t know why, clearly some residual optimism that ‘change is possible’…

    Today I noticed -

    “

    The UTMC will be set up as part of an intelligent infrastructure project with the aim of clearing congestion and improving air quality. The system will continuously receive data from a range of sources, such as journey time, traffic flow and air quality, and act autonomously to make changes to traffic signal timings on the road network to improve traffic flow.

    “

    https://www.ukauthority.com/articles/city-of-edinburgh-plans-for-digital-urban-traffic/

    Hard to know if this is ‘that’s way we do things’ officials or ‘technofix’ politicians -

    “

    Ambition to be world leader

    Council Leader Cammy Day said: “I’ve long been a champion of Edinburgh’s ambitions of becoming a world leading smart city – a digitally inclusive, data rich, and sustainable capital with services that are easily accessible by all our residents.

    “

    Posted 5 months ago #

  2. Frenchy
    Member

    I can imagine a scenario where they use this technology to reduce pedestrian waiting times without affecting traffic flows.

    But if that was the plan, they wouldn't be saying "intelligent infrastructure project with the aim of clearing congestion and improving air quality".

    Either they are entirely ignorant of induced demand, or they are not serious about the 30% car-kilometres reduction. Or both, I suppose.

    Posted 5 months ago #

  3. chdot
    Admin

    “Or both“

    Seems so.

    Or they are just submerged in their own worlds of smoke, mirrors and self-delusion.

    Posted 5 months ago #

  4. chdot
    Admin

    “

    In transportation engineering, traffic flow is the study of interactions between travellers (including pedestrians, cyclists, drivers, and their vehicles) and infrastructure (including highways, signage, and traffic control devices), with the aim of understanding and developing an optimal transport network with efficient movement of traffic and minimal traffic congestion problems.

    History

    Attempts to produce a mathematical theory of traffic flow date back to the 1920s, when American Economist Frank Knight first produced an analysis of traffic equilibrium, which was refined into Wardrop's first and second principles of equilibrium in 1952. Nonetheless, even with the advent of significant computer processing power, to date there has been no satisfactory general theory that can be consistently applied to real flow conditions. Current traffic models use a mixture of empirical and theoretical techniques. These models are then developed into traffic forecasts, and take account of proposed local or major changes, such as increased vehicle use, changes in land use or changes in mode of transport (with people moving from bus to train or car, for example), and to identify areas of congestion where the network needs to be adjusted.

    “

    https://en.m.wikipedia.org/wiki/Traffic_flow

    So, it all remains a holy grail.

    Posted 5 months ago #

  5. chdot
    Admin

    “

    In a free-flowing network, traffic flow theory refers to the traffic stream variables of speed, flow, and concentration. These relationships are mainly concerned with uninterrupted traffic flow, primarily found on freeways or expressways.[1] Flow conditions are considered “free” when less than 12 vehicles per mile are on a road. “Stable” is sometimes described as 12–30 vehicles per mile per lane. As the density reaches the maximum flow rate (or flux) and exceeds the optimum density (above 30 vehicles per mile), traffic flow becomes unstable, and even a minor incident can result in persistent stop-and-godriving conditions. “Breakdown” condition occurs when traffic becomes unstable and exceeds 67 vehicles per mile.[2] “Jam density” refers to extreme traffic density associated with completely stopped traffic flow, usually in the range of 185–250 vehicles per mile per lane.[citation needed]

    “

    https://knowledge4civil.wordpress.com/2016/12/13/traffic-flow-speed-density/

    So it’s just a THEORY?!!

    Posted 5 months ago #

  6. neddie
    Member

    So if 12 - 30 vehicles per mile is the minimum space those vehicles can take before flow breakdown, we need to reevaluate the number of kms taken up by all the extra cars projected to come into Edinburgh (on another thread somewhere)

    Posted 5 months ago #

  7. neddie
    Member

    I don't think there is anything wrong with the desire to have traffic "flow", as long as it doesn't lead to habitual speeding. After all, this means that a road is running at, or below, capacity.

    The problem comes from the belief that "one more lane", 'intelligent' traffic lights, 'relief' roads, or anything that increases capacity will fix it - it won't.

    The only genuine solution is to apply market principles, like we do for every other aspect of society bar almost none, and charge a pay-per-use road user fee.

    Hey, we could even ringfence that fee and use it to invest in alternative tranports, or better still reduce the need to travel by employing a whole series of contemporary planners to ensure that towns and cities are not built around car-dependency, etc etc

    Posted 5 months ago #

  8. neddie
    Member

    But instead we live in this shitty little parocial country where vested interests make it so that everyone living in a town or a city wants to own a motorcar* so they can "escape" to the countryside, or so they can drive some crazy short or crazy long distance to work, ruining, congesting and polluting both towns, cities and countryside alike.

    *Mountain bikes on the roof

    Why not actually make the towns and cities nice to live in, so people are able to live close to where they work and can enjoy their walks and bike rides directly from their front door? Without this FFS mentality of "MUST PUT BIKES ON CAR" "MUST DRIVE TO HILLS"

    Posted 5 months ago #

  9. chdot
    Admin

    It really is ‘all’ about traffic flow -

    “

    It is already helping the council manage traffic flow disruptions produced by large events such as International Rugby at Murrayfield, as well as catering for diverted and altered traffic patterns due to roadworks or incidents on the trunk road network, such as the City Bypass or M8. Journey time monitoring will be provided using data from 10 major arterial routes in the city, alongside real-time data, to Traffic Scotland to manage responses to disruptions on the trunk road network.

    “

    https://www.edinburgh.gov.uk/news/article/13826/edinburgh-delivers-smart-city-capabilities

    So with all that DATA perhaps a good time to look at where vehicles are coming from and going - and when, at look at why.

    AND THEN devise better ways of improving the flow of people around the city and (perhaps more importantly) in and out of the city.

    THEN working hard on improving/delivering better alternatives to car use - in line with the 30% commandment.

    To what extent the data includes pedestrian and cycle flow would be interesting to know.

    And indeed what use CEC, LB etc make of the data apart from marches, concerts, ‘events’ and ‘accidents’…

    Posted 5 months ago #

  10. neddie
    Member

    Blinded by technology and "data", they overlook the simple solutions

    Posted 5 months ago #

  11. Morningsider
    Member

    The idea of "traffic flow" works on trunk roads, where motorised traffic is physically separated from everything else.

    I would argue it is the wrong measure for urban streets. On main routes in urban areas, authorities should be looking to prioritise "people flow". The question isn't "How many cars can we squeeze down here" but "how can peple most efficiently move around these areas?" Pavements, cycleways and bus lanes are much more space efficient than carriageways carrying general traffic. You can tell this as they often look empty, while moving a great number of people.

    A Lothian bus could run along Comiston Road every 10 minutes and provide roughly the same carrying capacity as peak hour car traffic with average occupancy rates. The bus lane will almost always look empty. Until decision makers understand this, things will never change.

    Posted 5 months ago #

  12. Frenchy
    Member

    Re-reading the article, it's not clear if the plan is to start routinely adjusting traffic light timings, or only in the event of significant disruptions. Anyone know?

    The latter still has issues with private motor traffic being prioritised over sustainable modes of transport, but it's when it's used routinely that it would start to induce demand.

    Posted 5 months ago #

  13. chdot
    Admin

    “I would argue it is the wrong measure for urban streets. On main routes in urban areas, authorities should be looking to prioritise "people flow".”

    Yep, I think that’s the best way to look at it.

    “it's not clear if the plan is to start routinely adjusting traffic light timings”

    That’s a good point.

    “The latter still has issues with private motor traffic being prioritised over sustainable modes of transport, but it's when it's used routinely that it would start to induce demand.

    Another good point.

    I think there needs to be some ‘campaign’/attempt to find out what CEC really intends to do about traffic reduction.

    Posted 5 months ago #

  14. jonty
    Member

    As far as I understand it, the CEC control room can already remotely operate many of the key traffic lights in the city and has access to CCTV. Instead of investing in highly expensive extra technology, could they not just employ a couple of extra people to watch the screens at rush hour and press a few buttons to address problems as they occur? They're not really going to be able to squeeze much more capacity out of junctions with up-to-date equipment.

    Posted 5 months ago #

  15. chdot
    Admin

    So many ‘given’ assumptions/justifications in this -

    “

    Traffic management is essential in order to maintain the safe and efficient flow of traffic. The goal of any traffic management plan is to reduce congestion and improve safety. Traffic engineers use a variety of strategies to accomplish this goal, such as increasing the number of lanes, improving signage, adding traffic lights, and enforcing traffic laws. The aim of any traffic management plan is to ensure that traffic moves safely and efficiently. This is especially important in busy cities, where large amounts of traffic can cause major delays and even gridlock in some areas. The right traffic management plan can help reduce the risk of traffic accidents, as well as reduce the amount of time people spend waiting in traffic.

    “

    https://medium.com/@kittyschowalter7/the-top-five-reasons-why-traffic-management-is-important-29e07ff155f0

    Posted 5 months ago #

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