1. 2013 Mid-Continent Transportation Research Symposium
August 15, 2013
Gateway Hotel
Ames, IA

2. Evaluation of Mitigation for Safety Concerns on Low Volume, Unpaved Rural Roads in Iowa

3. Tom McDonald, PE Iowa Local Technical Assistance Program
Iowa State University
(515)

4. Background Total roads in Iowa ~ 114,000 miles Paved ~ 42,000
State ~9,300
Counties ~90,000
Municipal ~15,000
Paved ~ 42,000
Unpaved ~ 72,000 (63%)
Over one-half of all crashes and almost half of fatalities occur on local roads !

5. 2010 Institute for Transportation Research
Reviewed crash history on 2 lane rural roads in Iowa
State and local agency
Paved and unpaved
For local rural, low volume roads
Major crash involvement with younger drivers and higher speeds
In comparing crash performance vs. road characteristics;
Density, rate, & frequency
Unpaved roads with traffic volumes of vpd identified with poorest safety performance
More study recommended

6. 2011 – 2012 Research Project
Crash mitigation on rural, unpaved roads with traffic volume > 100 vpd
~ 4400 miles statewide, (average 44 miles/county)
Select study segments from central Iowa counties
Use multi-disciplinary approach to address crash history
Analyze results of mitigation selected.

8. Crash Maps

10. Selected Study Segments

11. Compile Segment Data

12. Crash history, 2001 through 2010 (10 years)
Story County, 530th (Grant) from NCL of Ames to SCL of Gilbert, 2.45 mi.
Crash history, 2001 through 2010 (10 years)
29 total crashes, 21 injuries, no fatalities
1 animal
1 ran Stop sign
3 FTYROR (from Stop sign and from uncontrolled intersection)
15 speed related
4 ROR
No adverse surface conditions reported
40 total drivers
22 teenage (55%)
1 +65
1 impaired driver
Objects struck
12 ditch/embankment
Hours of day for crashes
5 from 6:00 through 8:00, 17%
18 from 14:00 through 20:00, 62%

13. Next Steps
Meet with local agency officials in counties with selected segments
Determine interest in participating in study
Review crash history and recent safety enhancements
Engineering, law enforcement, educational efforts
Invite on field review of current conditions
Suggest and select appropriate mitigation
Engineering, law enforcement, school, and media
Meet with others with potential interest
Near-by school officials and driver instructors
News media

14. Field Reviews Note higher crash locations, actual and potential
Perform speed evaluations
Record conditions on images
Measure roadway width, document surface and geometric
conditions

19. Sequential Detail Report
Speed Evaluations
Sequential Detail Report
HI-Star ID:
7552
Begin:
Dec/08/11 14:00
End:
Dec/12/11 14:00
Street:
130th St
Lane: EB
Hours:
96.00
State: IA
Oper:
OOS
Period:
Sequential
City:
Posted: 55
Raw Count:
239
County:
Dallas
AADT Factor: 1
AADT Count: 60
Gap Time in
Headway
Count
Date / Time
Advice
Speed
Length
Seconds
in Feet
Tail Gating
2011/12/08 14:09:33.00
Normal 51
MPH
23.00 FT No 2
2011/12/08 14:35:03.00
Exceeded Maximum Length 30
14.00
Yes
[ Thursday, December 08, : :00 ]
Average Speed: 40
Average Gap:
Occupancy:
0.03 %
Classified Count:
Average Length:
18.00
Average Headway:
Tailgating Count: 3
2011/12/08 15:13:08.00
12.00 4
2011/12/08 15:17:33.00 52 5
2011/12/08 15:21:22.00 44
16.00 6
2011/12/08 15:30:06.00
Averaged Speed Only 47
32.00 7
2011/12/08 15:35:15.00 8
2011/12/08 15:42:40.00 73
21.00 9
2011/12/08 15:47:19.00 63 10
2011/12/08 15:51:17.00
19.00 11
2011/12/08 15:53:48.00 34
8.00 12
2011/12/08 15:56:47.00 56
25.00

20. Speeding violations by Day
Speeding violations by Day
130th Street Dallas County W B E
(>55)
(>65)
Sunday 19 5 8 2
Monday 3 7
AM Count Only
Thursday 9 6 11
PM Count Only
Friday 15 10
Saturday 14
Total 65 27 43
# of Violations
Count
301
239
Total Traffic Counted
% Violations.
22% 9%
18% 6%
Use to Select
Enforcement
Periods

21. Possible Mitigation Considered
Engineering Options:
Upgrade existing signing
Install delineators with appropriate colors on both sides
Remove or relocate roadside obstacles
Remove or trim existing vegetation in clear zone
Law enforcement Options:
Periodic patrols at high crash/violation times
Monitor speeds with recording devices
Monitor seat belt use
Occasional visits with driver instructors in high schools where appropriate
Educational Options
Article in local newspaper occasionally (annual?)
Annual presentation to new drivers in high school drivers ed. classes
Engineer, law enforcement, or LTAP

22. Examples of Mitigation Applied

23. Engineering Strategies

24. Law Enforcement

25. News Release
News Release In December of 2010, Iowa State University released a study titled “Safety Analysis of Low Volume Rural Roads in Iowa”. Several conclusions in that report emphasized the much higher crash rates and densities for many types of the crash events taking place on unpaved rural roads with traffic counts between 100 and 400 vehicles per day. Using the information gleaned from that investigation and report, a follow up study was begun in the fall of 2011 to review some typical area roads that fall in that category. Field reviews of several road segments in Story and nearby counties were conducted, possible crash causes noted and suggestions made for possible physical improvements made to clear delineate the roadside, if appropriate. A second phase of this study is to attempt to find possible other mitigation strategies that could possibly be used to reduce those high crash rates noted. Two short road segments in Story County were originally identified as study sites, and after conducting field reviews and speed studies and also holding discussions with local engineering and law enforcement officials, two strategies have been now been chosen to be employed. First, all existing signs along the routes will be replaced with ones of higher reflective value and secondly, additional enforcement will be employed for a period of time to hopefully slow traffic and also to help identify typical driver traits and actions that might account for the higher crash numbers that have been recorded rates noted. The Story County Sheriff’s Office will be begin conducting that additional enforcement this Friday and it will be continued for approximately two months. An analysis of before and after crash data is planned, but only after the improvements and enforcement have been in place for a two to three years. The original safety analysis report may be viewed on the Institute for Transportation website at

26. Meeting with High School Officials
Principal, driver educator, school bus supervisor
County engineer and deputy, Governors Traffic Safety Bureau, LTAP researchers
Shared general data from school district crashes & specific information about study segment
Discussed on-going and future plans of school district for addressing student driver safety

27. Findings
When high school was in close proximity, student drivers are involved in crashes to a significant extent
Speed also a major contributor to many crashes
Identifying other reliable contributors difficult on these roads
Multi-disciplinary approach to crash mitigation can be effective
Larger study sample across state may yield differing results
Insufficient time with this study to fully evaluate results

28. Volume vs. Frequency ??

30. Recommendations
Undertake expanded study to consider more samples across a broader area of the state
Promote study for reducing statutory 55 mph speed limit on unpaved roads, statewide or on higher crash segments
Post regulatory speed limit intermittently on unpaved roads with higher crash frequencies
Include mandatory minimum experience and instruction for operating a motor vehicle on unpaved roads in new driver training
Take advantage of multi-disciplinary opportunities to address crashes on unpaved rural roads

31. Questions