For my term paper in highway engineering class, I made a study of the ten most accident prone intersections in the city. I went to the main police station and looked at their wall map and just visually picked the ten most dense cluster of pins and then drove out to see what if anything was wrong at these intersections (this is called "graveyard engineering"). There indeed was at least one obvious factor at each location. I then drew sketches and made recommendations as applicable. Most of the accident causing factors were things that could be quite readily eliminated or alleviated without much effort or expense.
The professor did not return my paper to me with my grade, but I noticed a couple of months later that most of my recommendations had been implemented, so I think he must have passed my paper along to his good friend, the city traffic engineer.
The Iowa DOT publication gives Iowa DOT personnel and the local governments a procedure to follow for this kind of thing and establishes a routine for bringing problems to the attention of those who then can order a crew to go out and fix them. It also gives cover when citizens protest at being ordered to remove bushes, garden walls, or whatever from their property corners, since the reports (with the DOT instructions) will show why the work was ordered in simple terms that avoid charges of the engineers burying the public in math and technical mumbo-jumbo.
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Hans H. Coucheron-Aamot
[Retired]
Albuquerque NM
(505) 897-2554
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Original Message:
Sent: 08-12-2018 01:18
From: Surya Sarat Chandra Congress
Subject: Road Geometry Assessment during the Design period of pavement
The present trend that I observed with the DOTs is that they only design these parameters and seldom check them during the life of the pavement. Unless there are lot of accidents occurring, they don't check it. Don't you think they should check at least once in a 5 year check by following what IOWA manual specifies (i.e. go out to the field with a Sighting rod and target rod)?
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Surya Sarat Chandra S.M.ASCE
Arlington TX
(682)203-6894
Original Message:
Sent: 08-11-2018 04:57
From: Johnstone Wangusi
Subject: Road Geometry Assessment during the Design period of pavement
With modern advanced design softwares, those issues of sight distances are easily solved. I've used programs like Civilcad, 12D softwares which model & simulate the actual design scenario.
Regards
Johnstone
Original Message------
Greetings,
I have been involved with highway design for over 30 years. I have never seen a nice, simple study/approach like one mentioned (2002 Iowa). I myself do not consider this to be antiquated; rather, I think it is a magnificent approach.
Can you imagine the number of intersections an agency could study/measure in one summer, using a couple of young women or men; civil engineering students? Not only would this agency get some good data, these youngsters would gain experience. And while there is no need for a bunch of fancy equipment I would use an electronic rangefinder--many are now available.
I think we spend a lot more time evaluating intersection sight distance than most engineers. I see a trend further-and-further away from even considering it in the industry---we are seeing outright blunders, particularly with bridge work at intersecting streets. Be aware that the "heights" of the driver's eye, and the "object" vary from agency; some are more lenient.
The Iowa document was a nice surprise for me. Thank you.
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Scott Onishuk P.E., M.ASCE
Director
Santa Barbara CA
(805)563-0788
Original Message:
Sent: 08-10-2018 10:08
From: Surya Sarat Chandra Congress
Subject: Road Geometry Assessment during the Design period of pavement
I have assumed the same that they are obsolete methods but a report by IOWA in 2002 (https://nacto.org/docs/usdg/sight_distance_study_Iowa.pdf) made me think if those methods are still used or not. If you go to the page 4.6 in the PDF, they mentioned that they use sighting and target rods for measuring the stopping sight distance and sight triangles. So I was interested to know what kinds of equipment are being used by different DOTs at present for those purposes. Any information links will be helpful regarding those. Thank you for your response.
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Surya Sarat Chandra S.M.ASCE
Arlington TX
(682)203-6894
Original Message:
Sent: 08-09-2018 09:13
From: Hans Coucheron-Aamot
Subject: Road Geometry Assessment during the Design period of pavement
I think you are referring to distance measuring by transit and stadia rods. We were taught about this in my introductory surveying class 65 years ago and I have actually seen it used once in the field since, when a one pickup contractor used it for constructing a long levee with waste excavation material where accuracy was not particularly important.
Today, almost all surveying is done by GPS and electronic measurements. Hardly anyone even knows how to work a transit or "throw" a chain, much less use stadia measurements.
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Hans H. Coucheron-Aamot
[Retired]
Albuquerque NM
(505) 897-2554
Original Message:
Sent: 08-07-2018 22:03
From: Surya Sarat Chandra Congress
Subject: Road Geometry Assessment during the Design period of pavement
Thank you. I am also following the AASHTO Little green book 2011. But I want to know more about the instruments used for traditional methods. For example, I read that sighting and target rods were used by IOWA state to measure sight distance. Do you think most of the states in USA are using it still? In the same way which equipment is used for transverse slope and other important road geometry features?
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Surya Sarat Chandra S.M.ASCE
Arlington TX
(682)203-6894
Original Message:
Sent: 08-06-2018 08:32
From: Alfredo Vargas
Subject: Road Geometry Assessment during the Design period of pavement
Locations where accidents, congestion, drainage problems or pedestrian accessibility compliance (to name a few examples), have been recorded during their operation, and have been identified as needing improvements, are typically slated for design with the use of a design guide.
Government agencies typically have their own design guide that use the AASHTO Greenbook as their foundation. Then, they include their own priorities when they deviate or are not present in the AASHTO Greenbook.
Existing geometric features are assessed during the design process for the desired improvement.
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Alfredo Vargas P.E., M.ASCE
Design Engineer
Newton MA
(617)894-7024
Original Message:
Sent: 08-03-2018 16:35
From: Surya Sarat Chandra Congress
Subject: Road Geometry Assessment during the Design period of pavement
What traditional methods are adopted by various government transportation agencies for measuring various geometric features (width of pavement, length of clear view of pavement (stopping sight distances), horizontal curve radius) of the pavement during the middle of its design life period?
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Surya Sarat Chandra S.M.ASCE
Arlington TX
(682)203-6894
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