Mike on Traffic

Twin Cities Streets for People

I have become a contributor to Twin Cities Streets for People, where I'll blog more about new urbanist transportation issues.  Check out my post about sidewalks in St. Louis Park.

Traffic Signal Lights - Round vs. Square

Notice anything different about the signal on the left?  Art Lebedev came up with this design which he details on his blog.  It uses square indications instead of round ones, which Art contends are easier to see and more aesthetically pleasing.  The round indications are a remnant of the first traffic signals that were created in the 1910's and 1920's.  Those original electrical signals were circles because they used light bulbs.  Now we use LEDs and could easily switch to a different shape. 

A crazier idea - why do we need three indications stacked on top of each other (answer - it used to be for the color blind)???  Now that we have LEDs, we could put different indications in one spot.  We could combine the traditional colors with traditional shapes to reinforce the message.  This would reduce the size and cost of the signal indications, which in turn would allow us to use smaller metal poles which would save significant money.  Then we run them with solar panels and wifi saving cable and wiring.....

NCITE Awards - Congratulations to Campbell and Culver

NCITE's (North Central Section of the Institute of Transportation Engineers) annual meeting was held Saturday.  Congratulations to Tom Campbell (Mn/DOT - retired) for receiving the Transportation Professional of the Year Award and to Marc Culver (City of Maple Grove) for receiving the Young Transportation Professional of the Year Award.  Tom and Marc are very deserving.  They are both well respected in the profession and have been significantly involved in NCITE throughout their careers.

Sight Distance Explained

According to the American Association of State Highway and Transportation Officials' (aka AASHTO) A Policy on Geometric Design of Highways and Streets (aka the Green Book), "Sight Distance is the length of roadway ahead visible to the driver.  The minimum sight distance available on a roadway should be sufficiently long to enable a vehicle traveling at or near the design speed to stop before reaching a stationary object in its path."  In an attempt to demystify my industry - it means that a motorist should be able to see cars, deer, kids, etc. at an intersection in enough time to stop before hitting them. 

Here is a picture from the corner of my block showing exactly how the sight distance is violated.  This row of hedges makes it so you can't see around the corner.  For high speed roadways, there are a series of technical calculations in the Green Book that engineers go through to figure out the design of the road and the triangles at intersection corners that need to remain clear of objects that will block the view. 

I drew up a quick rule of thumb here for residential neighborhoods:  go 30 feet in each direction from the corner, draw an imaginary line from those points, and keep this imaginary triangle clear of things that will block the view of oncoming traffic.  This is a pretty clear cut way to improve the safety in our neighborhoods.   

NEW Trip Generation, 8th Edition

I received the brand new, 8th Edition of the Institute of Transportation Engineers' (aka ITE) Trip Generation informational report.  See my previous post explaining what this report is and how it is used.  The 7th Edition should no longer be cited in traffic studies.

I am proud to see Traffic Data Inc. listed as Source 621.  We contributed data on pharmacies with drive through lanes and coffee shops (with and without drive through lanes).  Now I can stop referencing our special studies and just use the data published in Trip Generation.

One large change I am happy to see is related to banks.  The new Trip Generation removed all of the data prior to 2000 in recognition of online banking, atms, and shifted banking hours.  The result is that the traffic predicted to come out of banks has been approximately cut in half.  This matches what I have instinctively been thinking (and congratulations to Tom Sohrweide of SEH who has been cutting his trip generation from banks in half based on his judgment).  Now I have the data to back me up and I don't need to cringe when a developer tells me he is thinking a bank will go on one of his outlots.

Traffic Data Inc Selected for Hennepin County Consultant Services List

A little shameless self congratulations -

We just found out we have been selected by Hennepin County to provide data collection and traffic engineering services in 2009 and 2010 under the County's consultant services list.  This is a blanket agreement that develops a pool of consultants to work on small projects for the County (there is a $200,000 cap in total fees for the two years).  We are looking forward to working with Hennepin County staff!