Roadways and Safety


The final white papers for the Regional Transportation Plan update are out:

The first paper has the predictable review of congestion, but I found two interesting factoids as well: it’s not just the road systems that’s aging, but also our drivers, and this will affect everything from engineering stopping distances (our reaction times will be slowing) to putting bigger type on road signs. The other is a concise little graph on p. 24 showing the efficacy of ramp meters in keeping travel speeds up.

On the topic of safety, the paper reflects the need to make this a greater area of focus in all our transportation planning and operations. We need to introduce a culture of safety throughout.


5 responses to “Roadways and Safety”

  1. The other is a concise little graph on p. 24 showing the efficacy of ramp meters in keeping travel speeds up.

    Ok, my question is:
    Why is I5, in North Portland, allowed to fall to LOS F when, presumably, metering could keep the # of cars entering low enough to have LOS E and a much higher throughput?

    The stop and go conditions actually have a much lower vehicles per hour than if they aggressively metered.

    (As I understand it, the problem is that when too many cars try to use a road, its capacity actually falls from around 1800 vehicles per hour to a few hundred per hour. The purpose of ramp metering it to keep the freeway at its maximum number of vehicles per hour.)

    Why is I5 being permitted to fall in capacity be allowing too many vehicles on to it. (As someone described, it is like allowing too many grains of rice into a restriction – they jam.)

    Thanks
    JK

  2. The other is a concise little graph on p. 24 showing the efficacy of ramp meters in keeping travel speeds up.

    What is actually interesting about that graph is that it is in the report. It shows the speed of traffic on the freeway, ignoring the impact of ramp meters on the time it takes to get on the freeway. The reality is that the ramp meters divert traffic off the freeway onto local streets and create congestion on the roads that provide access to the freeway.

    According to the report: “The data for this graph came from an ODOT study that demonstrated ramp metering saved nearly 15 minutes on the commute from Hillsboro into Portland.”

    This conclusion seems to be a simple computation of distance and the improved speed once someone is on the freeway. It ignores entirely the time it takes to get on the freeway or the impact on people who have their access to the freeway reduced by the meters.

    It should leave little doubt about what is in store for people in North and Northeast Portland with the expansion of the I5 bridge. The meters will be managed to improve freeway speed for Clark County commuters while the residents of North and Northeast Portland sit waiting at meters.

  3. “Why is I5, in North Portland, allowed to fall to LOS F when, presumably, metering could keep the # of cars entering low enough to have LOS E and a much higher throughput?”

    LOS F is nearing full capacity. It is only when congestion gets worse that throughput starts to decline. LOS E actually has less throughput than LOS F, but at higher speeds.

  4. Exhibit E: Policy 20.2…Objective: Place less priority on projects and programs that modernize or expand the region’s transportation infrastructure.

    Aren’t we doing precisely the opposite when we heavily invest in streetcars, trams, and light rail at the expense of simply maintaining our existing transportation infrastructure?

    I mean, we invest all that money for the streetcar to South Waterfront –and a tram when you get there– but we can’t be bothered to insist the sidewalks be repaired –or provided– to walk there?

    And, in the meantime, we see the continued degradation of our EXISTING transit system. Our #14 was so packed last night –and that’s with some riders at my stop unable to get on– that the half-dozen fare inspectors that intended to get on at the Hawthorne Bridge stop, and 2 tried, gave up. There was no way for them to move through the bus.

  5. Let’s put this in the context of the rest of the policy:

    Emphasize the maintenance, preservation and effective use of transportation infrastructure in the selection of the RTP projects and programs.

    1. Objective: Place the highest priority on projects and programs that preserve or maintain the region’s transportation infrastructure and retrofit or remove culverts identified in the region’s fish passage program.

    2. Objective: Place a high priority on projects and programs that preserve or maintain the region’s transportation infrastructure

    3. Objective: Place less priority on projects and programs that modernize or expand the region’s transportation infrastructure.

    This policy is still largely a question of where capital dollars go.

    If your argument is about whether we have the capital/operating balance wrong, I won’t disagree with you. Some of this is driven by federal policy, but some if it is our own local and regional decision-making processes.

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