2008 06 11 - 3301 - Washington DC - 16th St at MD384, EasternAve, NPortalDr - S leg : 無料・フリー素材/写真
2008 06 11 - 3301 - Washington DC - 16th St at MD384, EasternAve, NPortalDr - S leg / thisisbossi
| ライセンス | クリエイティブ・コモンズ 表示-継承 2.1 |
|---|---|
| 説明 | 2014 07 03 - Used by Fast Co Design--------------------------------------------------------This photo shows a lot of interesting things. Well... interesting if you work in my industry, or perhaps if you are a really engaged transportation advocate.First-This actually shows a two-stage pedestrian crossing, whereby pedestrians cross to the median and then to the other side of the roadway as two separate maneuvers, each with its own signals. This is why the signals appear to show conflicting messages; they're actually doing something that does make some sense.Second-That far signal is an old one: textual messages are no longer used. Symbolic messages (like the near signal) better bridge language barriers (as well as target those who can't read).Third-The countdown pedestrian signals display the countdowns during the WALK phase, which is not compliant with the MUTCD (the go-to book of traffic engineering guidelines & requirements).In general, showing the countdowns during the WALK phase can be reassuring to pedestrians: it makes it seem like there is plenty of time remaining. However, this time can be deceiving: it can be shortened, truncated, or suddenly turn dark for a multitude of reasons. Running countdowns during the walk phase means that, where signals have sensors & vary the time according to traffic (technical term: "actuated"), the countdown doesn't actually know when it needs to count down to. This means you can see a signal suddenly jump, counting either 93 - 92 - 91 - 90 - 5 - 4 - 3 - 2 - 1... or the other way: 4 - 3 - 2 - 1 - 75 - 74 - 73...The Flashing Don't Walk phase is supposed to be timed to let a pedestrian cross the road at 3.5 ft/s. So a 50 ft road would require 14s of Flashing Don't Walk. However, DC's standard is that the Flashing Don't Walk comes up when the countdown hits 5, presumably on the assumption that users would are smart enough to use the countdowns during the walk phase to determine whether they can make it across in time.I like this in concept, but *legally* the law says that a pedestrian may enter the road during Walk... so at 6 seconds, a pedestrian can legally enter a 6-lane arterial & make their way across, even though they'll be unlikely to make it to the other side in time. The government may be liable if a pedestrian doesn't make it across in time & gets hit by a motorist with a green light. This is especially an issue for disabled demographics, which can be slower to cross as well as less able to see/hear. A blind user may enter a crossing based on the sounds indicating it's a Walk signal, but become stranded when they switch to Flashing Don't Walk sounds with only 5 seconds remaining.Problem is, as a typical able-bodied user: I really REALLY like the countdowns on Walk. And so does just about everybody else. Which makes it difficult in the neighboring jurisdictions in having to regularly explain why we cannot legally use them as DC does. As a user I love them, but as a traffic engineer I loathe them. |
| 撮影日 | 2008-06-11 13:07:57 |
| 撮影者 | thisisbossi |
| タグ | |
| 撮影地 | Washington, District of Columbia, United States 地図 |
| カメラ | Canon PowerShot A650 IS , Canon |
| 露出 | 0.005 sec (1/200) |
| 開放F値 | f/4.0 |
| 焦点距離 | 13745.7045454545 dpi |