Resources to Address Speed Management in Rural Communities

Nationally, speeding is a contributing factor in 31 percent of fatal crashes.

The Problem

Nationally, speeding is a contributing factor in 31 percent of fatal crashes (NHTSA 2008).

Many rural communities have developed around highways or major county roads. As a result, the main street through small rural communities is often part of a high-speed rural highway. Highways and county roads are characterized by high speeds outside the city limits, which then transition into a reduced speed section through the rural community. Consequently, drivers passing through the community often enter at high speeds and maintain those speeds as they travel through the community. Traffic calming in small rural communities along major roadways is common in Europe, but the US does not have experience with applying traffic-calming measures outside of major urban areas.

Speeding in rural areas is particularly problematic since rural agencies and communities lack the resources for regular enforcement while the remoteness of much of the system makes timely emergency response difficult.

A list of general resources developed in Iowa to address speed management in rural communities is found here.

Summary of Speed Reduction Countermeasures

A summary of known performance for each speed reduction countermeasure is provided in the table below.

Speed Reduction Countermeasures Highest Speed Impact (mph) CMF1 Other Crash Impacts1 Cost2 Usage Within Iowa
horizontal physical displacement
bulb-outs, neck-downs, chokers, or mid-block crossings -2.60 $$$ occasional
chicanes or serpentines -6.20 $$$ no experience
roundabouts 0.27 to 0.58 $$$ occasional
transverse rumble strips 0.64 to 0.66 $$ not tested
vertical physical displacement
raised intersections 1.05 not tested
speed humps and tables -10.0 $$$ occasional
speed lumps, slots, and cushions -9.0 not tested
center islands 0.29 to 0.61 $$ common
vertical centerline treatments -3.0 $ tested
shoulder widening to narrow travel lanes -0.00 $$ tested
four- to three-lane conversions -5.0 0.47 to 0.63 widespread
landscaping -7.0 not tested
community gateways -5.0 0.98 $$$ common
pavement markings
transverse lane markings -5.0 $$ tested
surface treatments -9.0 $$ tested
pavement marking legends 0.00 $$ tested
wide edge lines 0.57 to 1.05 $$ no experience
traffic control signs
radar-actuated dynamic message display sign -7.00 $$$ tested
radar-actuated LED sign -7.00 $$$ tested
photo-radar reinforcement $$$ occasional

(1) Actual crash reductions and CMF will vary by crash type. CMF and crash reduction values which were determined to be the most appropriate for Iowa rural two-lane roadways were selected from a range of studies.

(2) Estimated installation costs ($ < $5,000; $$ $5,000 to $10,000; $$$ >$10,000) — actual cost depends on size of treatment location, actual product selected, whether treatment is done in conjunction with other activities such as resurfacing/paving, etc. Maintenance costs can vary considerably but are not estimated.


NHTSA. Traffic Safety Facts 2007 Data: Speeding. DOT HS 810 998. National Center for Statistics and Analysis, National Highway Traffic Safety Association, 2008.

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