Intersection AnalysisMarch 2012

03/2012 1

Intersection Crash Collection Years = 2007-2011 Remove animal crashes (TYPE= 08 and 09) Influence areas = 150’ radius

be aware of other points of conflict (intersections, drives, RR, etc)

Select adjacent counties to assure you are getting ALL crashes at intersections at county borders

03/2012 2

Configuration T – T intersection X – Four leg intersection TT – Two T intersections (at curve)

03/2012 3

ADT

Columns configured for entering approach volume Enter two-way ADT for each leg Add all legs and divide by 2

http://www.dot.state.mn.us/traffic/data/html/volumes.html Intersections within shaded areas need volumes from City map Default ADT for roadways without known volumes, refer to emailed ADT

guidelines If you find anomaly, put in your estimate and highlight cell in red (make

note) Anomalies include but are not limited to large commercial entrances (Wal-Mart,

factories, etc) Major ADT = Largest Movement (typically uncontrolled approaches) ADT ratio should never be greater than 1.0

03/2012 4

ADTKeep in mind this default would only be needed at 4 or more leg intersections that have a leg that is NOT State, CSAH, CR, or MSAS,

They use the following values: City streets (where city is <5,000 pop) = 369 City streets (where city is 5,000 to 50,000 pop) = 674 City streets (where city is >50,000 pop) = 824 Township roads = 54 Other roads (Unorganized township roads, state forest roads, etc) = 4

I suggest that we use these default values. I would offer other suggestions: 1) In rural areas, if opposite county leg has ADT <55, use that lower number for the township road. 2) In cities, if opposite county or MSAS leg is less than default value, use that lower value for the city

street. 3) If you suspect the ADT is significantly different than the default, we use the default but highlight

that cell. We could then ask the county for their best guess, or make our best guess.

There may be a few more guidelines needed, but we do not need to try to get a precision that is not warranted. 

03/2012 5

Skew Yes – 15 degrees or greater No – everything else

No

Yes03/2012 6

On/Near Curve Yes – on or within 1,000’ feet of curve No – everything else

03/2012 7

Development at Intersection Yes – aerial shows a commercial

development with access near intersection in any quadrant (gas station, restaurant, etc), school

No – residential, farms, church

Within ~200’

03/2012 8

Railroad Crossing Yes – railroad crossing of any approach

within 500’ of intersection No – everything else

03/2012 9

Intersections with minor leg Gravel Roads Leave in as part of prioritization exercise Be sure to add note and be sure they do not

receive pavement marking projects This does not include intersections with 500’

of paved approach

03/2012 10

Aerials for High Priority Intersections Download .jpeg image from Mn/DOT’s

Interactive Base Map www.dot.state.mn.us/maps/gisweb/

03/2012 11

County Inputs Traffic control device

signal, thru-STOP, All-way STOP, Yield Flashers (if yes, overhead or sign mounted) Street light installed (yes/no) Distance to previous stop

Greater than 5 miles = yes

Analysts can update as necessary

03/2012 12

Questions Highlight cells for follow-up

Yellow cells – “I’m unsure” Red cells – “Loren, figure this out”

03/2012 13