Tag Archives: FHWA

How those little blue lights make intersections safer

A story from WCCO-TV last week answered a question that has likely been puzzling many commuters passing through Ramsey County: what are those blue lights popping up on traffic signals?

The report explains that the blue lights illuminate when a traffic signal changes to red, allowing a patrol officer to witness and enforce a signal violation more easily and safely. What the report doesn’t explain is the safety benefits to be gained from increased red light enforcement.

In Ramsey County, the proposal for a recent large deployment of blue lights came from traffic engineers, not police.

“Our county safety highway program conducted by MnDOT indicated a lot of right-angle crashes related to people running red lights,” said Ramsey County Planner Joseph Lux. “These are typically the accidents with the severest injuries.”

As part of the statewide Towards Zero Deaths (TZD) initiative in July 2013, MnDOT worked with counties to develop safety plans that emphasize low-cost, high-value safety improvements.

A federal grant is helping fund the installation of 128 blue lights at 49 intersections in Ramsey County (see locations) over the next two weeks. Deputies will begin enforcement later this month, but the hope is that the blue lights will be so effective,  active enforcement won’t be necessary long-term.

A blue light, positioned on each of the four corner intersection poles, turn on whenever the opposite signal light turns red.

“The comments we’ve received from local police is they don’t want to write tickets; they just want people to quit running red lights,” Lux said.

IMG_2431
Blue light indicators were affixed to existing signal poles at Lexington Avenue and Larpenteur Avenue in Roseville.

The blue light indicators allow a police officer to view an infraction from many viewpoints, instead of having to pursue the offending vehicle through the intersection. Also only one squad is required to patrol an intersection; not two.

The blue light indicators have been shown to increase traffic safety. In Florida, crashes due to people running red lights fell by 33 percent, according to a low-cost safety improvement pooled fund study conducted on behalf of MnDOT and 37 other states.

Unlike Florida’s blue lights, Ramsey County’s are being placed on the signal pole, instead of the masthead. They’re more prominent than a couple indicators the county tried previously at accident-prone intersections in Little Canada and Maplewood.

“They’re bright and noticeable to the public, but not distracting, like the ones Florida puts on the masthead,” Lux explained.

According to WCCO-TV, the blue lights are funded by a $120,000 federal grant, with $13,000 in matching local funds.

Temporary signs will be put up by Ramsey County to notify the public of the new indicators.

A few other Minnesota communities — including Blaine, Crystal, Olmsted County and Dakota County — have also installed blue light indicators in recent years.

Lux explained that Ramsey County is installing blue lights on intersections that are easily enforced by law enforcement, as well as those that aren’t, in hopes that the public will obey them all because of the heightened presence.

Six effective low-cost safety improvements for roads

For the past 10 years, Minnesota and 37 other states have pooled their resources to test the effectiveness of roadway safety improvement strategies. The project, appropriately titled “Evaluation of Low-Cost Safety Improvements,” evaluates key strategies laid out in a national guidebook aimed at reducing the number of annual highway deaths.

Participating states say the project, which has now been extended a total of eight times beyond its original scope, has been a resounding success. MnDOT Safety Engineer Brad Estochen said the pooled-fund study has provided state DOTs much-needed evidence to gain support for implementing new safety improvements.

“Some states want to do a certain strategy, but don’t have the institutional support,” Estochen said. “Through the collaboration of the Peer Exchange, they have national results they can point to.”

We asked Estochen, MnDOT’s technical liaison for the pooled fund, to name his top strategies to come out of the study.

Traffic calming measures

Roadway

One phase of the study used simulated driving scenes to examine methods of traffic calming (i.e., getting drivers to slow down) in  rural towns. The research found that drivers were most impacted by chicanes — extra curves in the road — and the presence of parked cars on the street. An alternative strategy, curb extensions (also called “bulb-outs”), was found to offer only a small potential safety benefit or no benefit at all.

(Read more about this phase of the study.)

Nighttime visibility improvements

DSC_6498

Researchers also looked at ways of improving nighttime driver visibility on rural roads. Edge lines and post-mounted delineators were selected as the best alternatives for improving curve visibility at night, with curve detection improving 12 percent to 70 percent due to enhanced edge lines. The results are significant, since horizontal curve sections of two-lane rural roads are a major source of roadway fatalities.

(Read more about this phase of the study.)

Flashing beacons at stop-controlled intersections

One way to make drivers aware that they’re approaching a stop sign is to add a flashing beacon to the intersection. Researchers installed various configurations of flashing beacons at more than 100 sites in North and South Carolina and examined the crash data before and after installation.

Courtesy of K-Kystems
Courtesy of K-Kystems

Results indicate that standard flashing beacons, as well as some “actuated” beacons (i.e. those that only turn on when traffic is approaching the intersection), are not only effective at reducing crashes, but also economically justifiable based on cost-benefit calculations.This research helped pave the way for more widespread adoption of Minnesota’s Rural Intersection Conflict Warning Systems (RICWS).

(Read more about this phase of the study.)

Edgeline rumble strips

DSC_4106pse

Edgeline rumble strips on curves were shown to significantly improve safety in the third phase of the study, which tested a variety of techniques.

Whereas rumble strips are traditionally ground into centerline or on the shoulder, Kentucky and Florida experimented with placing rumble strips right along the white edgeline of curved sections of road. This method was shown to reduce overall crashes by 29 percent.

(Watch the FHWA website for updates on this phase of the study.)

Red light enforcement devices

Red light indicator
In Florida, crashes due to people running the red light fell by 33 percent thanks to a small light that turns on when the signal turns red. This little light bulb, which is placed on top of a signal, allows for a police officer to sit at the other end of the intersection rather than pursue a car right through the intersection. Not only is it safer, but motorists are also more likely to obey the signal if they know police might be watching on  the other side.

Researchers are also still collecting data on the other techniques studied in phase three, including surface friction treatments on curves and ramps and larger curve warning signs (called chevrons). Watch the FHWA website for updates.

Wider roads in rural areas

manufacturing

Could simply shifting the edge lines of a rural road reduce the number of accidental drive-offs?

Yes, according to this study, which evaluated the effectiveness of various lane-shoulder width configurations on rural, two-lane undivided roads using data from Pennsylvania and Washington.

In general, results were consistent with previous research, showing crash reductions for wider paved widths, lanes and shoulders. For specific lane-shoulder combinations, the study found a general safety benefit associated with wider lanes and narrower shoulders for a fixed pavement width; however, there are exceptions. The report has a chart that shows the optimal lane-shoulder combinations for different sizes of roads.

In theory, there should be no additional cost for these strategies, as an edgeline can be re-striped as part of an existing resurfacing project.