Spatial Effectiveness of Speed Feedback Signs

Santiago-Chaparro, Kelvin R.; Chitturi, Madhav; Bill, Andrea R.; Noyce, David A.

doi:10.3141/2281-02

Cited by 18 publications

(14 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The City of Boston installed speed feedback signs together with posted speed limit signs at selected locations, which previous research found to be an effective method for reducing speeds at desired locations 17 18. However, the study did not evaluate the effects of the speed feedback signs, due to a lack of sites near these signs.…”

Section: Discussionmentioning

confidence: 99%

Lowering the speed limit from 30 mph to 25 mph in Boston: effects on vehicle speeds

Cicchino

2019

Inj Prev

View full text Add to dashboard Cite

IntroductionEffective 9 January 2017, the default speed limit on Boston streets was reduced from 30 mph to 25 mph. This study evaluated the effects of the speed limit reduction on speeds in Boston.MethodVehicle speeds were collected at sites in Boston where the speed limit was lowered, and at control sites in Providence, Rhode Island, where the speed limit remained unchanged, before and after the speed limit change in Boston. A log-linear regression model estimated the change in vehicle speeds associated with the speed limit reduction. Separate logistic regression models estimated changes in the odds of vehicles exceeding 25 mph, 30 mph and 35 mph associated with the lower speed limit.ResultsThe speed limit reduction was associated with a 0.3 % reduction in mean speeds (p=0.065), and reductions of 2.9%, 8.5% and 29.3 % in the odds of vehicles exceeding 25 mph, 30 mph and 35 mph, respectively. All these reductions were statistically significant.ConclusionsLocal communities should consider lowering speed limits to reduce speeds and improve safety for all road users. The current practice of setting speed limits according to the 85th percentile free-flow speeds, without consideration of other characteristics of the roadway, can be a hurdle for local communities looking to lower speed limits. Updated state laws that allow municipalities to set lower speed limits on urban streets without requiring costly engineering studies can provide flexibility to municipalities to set speed limits that are safe for all road users.

show abstract

Section: Discussionmentioning

confidence: 99%

Lowering the speed limit from 30 mph to 25 mph in Boston: effects on vehicle speeds

Cicchino

2019

Inj Prev

View full text Add to dashboard Cite

show abstract

“…Santiago-Chaparra et al [40] studied the effectiveness of a dynamic speed feedback sign on a rural two lane highway in Wisconsin. The DSFS displayed a flashing speed reading when an approaching vehicle was above the speed limit and provided a steady display when the approaching vehicles speed was below the speed limit.…”

Section: Effectiveness Of Dynamic Speed Feedback Sign Systemsmentioning

confidence: 99%

Crash Modification Factors for Dynamic Speed Feedback Signs on Rural Curves

Hallmark¹,

Qiu²,

Hawkins³

et al. 2015

JTTs

View full text Add to dashboard Cite

A large number of crashes occur on curves even though they account for only a small percentage of a system's mileage. Excessive speed has been identified as a primary factor in both lane departure and curve-related crashes. A number of countermeasures have been proposed to reduce driver speeds on curves, which ideally result in successful curve negotiation and fewer crashes. Dynamic speed feedback sign (DSFS) systems are traffic control devices that have been used to reduce vehicle speeds successfully and, subsequently, crashes in applications such as traffic calming on urban roads. DSFS systems show promise, but they have not been fully evaluated for rural curves. To better understand the effectiveness of DSFS systems in reducing crashes on curves, a national field evaluation of DSFS systems on curves on rural two lane roadways was conducted. Two different DSFS systems were selected and placed at 22 sites in seven states. Control sites were also identified. A full Bayes modeling methodology was utilized to develop crash modification factors (CMFs) for several scenarios including total crashes for both directions, total crashes in the direction of the sign, total single-vehicle crashes, and single-vehicle crashes in the direction of the sign. Using quarterly crash frequency as the response variable, crash modification factors were developed and results showed that crashes were 5% to 7% lower after installation of the signs depending on the model.

show abstract

“…The effectiveness of DSFS also depends on their positioning and message. On straight sections of roadway, the greatest speed reductions are observed upstream of the sign (20,21), with diminished effects downstream of the sign (21). These findings have led to the recommendation of that the sign be positioned at or before the critical location or hazard (22).…”

Section: Introductionmentioning

confidence: 99%

Driver Response to a Dynamic Speed Feedback Sign on Freeway Exit Ramps Based on Sign Location, Interchange Type, and Time of Day

Mahmud

Motz

Holpuch

et al. 2021

Transportation Research Record

View full text Add to dashboard Cite

A series of field evaluations was performed at three freeway interchange ramps in Michigan that possessed significant horizontal curvature to assess the impacts of a dynamic speed feedback sign (DSFS) on driver speed selection and brake response while approaching and entering the ramp curve. A DSFS with a 15 in. full-matrix display was temporarily installed at each of the three exit ramp locations. The sign was programmed to display the same feedback message at each location, which included the speed number for all approaching vehicles, which alternated with a “Slow Down” message for vehicles approaching above 40 mph. The effectiveness of the feedback sign was tested across various sign locations (at the point of curvature versus 350 ft upstream), interchange types (system versus service), time of day (peak versus off-peak), light conditions (daylight versus darkness), and vehicle types (passenger vehicles versus trucks). Compared with the pre-DSFS site condition, the DSFS reduced curve entry speeds and improved brake response at two of the three ramp locations. In general, the greatest beneficial effects on driver behavior were achieved when the DSFS was positioned at the point of curvature, during which curve entry speeds were reduced by approximately 2 mph. These findings were consistent between the system interchanges and service interchanges, and across all vehicle types. The DSFS was also found to be most effective during daytime off-peak periods compared with peak periods and at night. Further evaluation of DSFS at additional ramp locations, and considering an expanded set of conditions, is recommended.

show abstract

Spatial Effectiveness of Speed Feedback Signs

Cited by 18 publications

References 7 publications

Lowering the speed limit from 30 mph to 25 mph in Boston: effects on vehicle speeds

Lowering the speed limit from 30 mph to 25 mph in Boston: effects on vehicle speeds

Crash Modification Factors for Dynamic Speed Feedback Signs on Rural Curves

Driver Response to a Dynamic Speed Feedback Sign on Freeway Exit Ramps Based on Sign Location, Interchange Type, and Time of Day

Contact Info

Product

Resources

About