RFP: Traffic Forecasting Accuracy Assessment Research


TRB's National Cooperative Research Program (NCHRP) has issued a request for proposals to analyze and improve the accuracy, reliability, and utility of project-level traffic forecasts. Proposals are due October 13, 2016.

This Summary Last Modified On: 8/31/2016


Read more: RFP: Traffic Forecasting Accuracy Assessment Research

ITS Benefits >> Overall benefit-cost ratio for traffic incident management-oriented ITS program estimated to be 3.16.

The Michigan Department of Transportation (MDOT)’s strategic plan for Intelligent Transportation Systems (ITS) revolves around attaining and demonstrating key mobility, safety, productivity, energy and environment, and customer satisfaction benefits at a reasonable and sustainable level of investment. As of 2013, MDOT operates and maintains over 800 ITS devices on over 500 miles of highways. The research team was tasked with evaluating the return on investment of the newest major ITS construction projects, which have introduced a large number of new applications and devices. The evaluation entailed collecting data from the different traffic operations centers (TOCs), surveying the public, and analysis through the application of statistical modeling, microsimulation, and a tiered cost-benefit analysis.

Methodology
A traffic microsimulation software package was used to quantify benefits from "with/without" ITS scenarios with regards to freeway incident management based on AADT, ITS device density, economic impact, and crash/incident history. This study identified highway segments with the highest potential for positive ITS benefit. The objective of corridor microsimulation was to quantify detailed benefits resulting from MDOT ITS. In this project, the research team selected a sample of representative corridors from each of the three MDOT TOCs. MDOT’s incident management programs strive to produce savings in congestion cost, reduce incident duration, reduce motorist delay, and improve safety by minimizing the probability of secondary crash occurrence.

Seven major MDOT freeway corridors were selected for the simulation study. The corridor characteristics under consideration for site selection included AADT, ITS device density, economic impact and crash/incident history. The goal of the study was to choose a representative selection of corridors whose analysis and subsequent results could be transferrable to other corridors statewide.

Benefits

The overall estimated benefit-cost ratio for ITS deployments in Michigan is 3.16. Specific benefit-cost ratios were developed for four specific ITS devices and services:

  • Dynamic message signs, 3.81
  • Closed-circuit television, 3.95
  • Microwave vehicle detection systems, 1.02
  • Freeway courtesy patrol, 3.82

Read more: ITS Benefits >> Overall benefit-cost ratio for traffic incident management-oriented ITS program...

Passengers at risk in small overlap crashes

ARLINGTON, Va. — Drivers of vehicles with good small overlap front ratings from the Insurance Institute from Highway Safety can expect to be protected well in a frontal crash involving the left corner of the vehicle. But how would the passengers sitting next to them fare in a right-side small overlap crash? A new study shows that good protection doesn't always extend across the front seat.

The Institute conducted 40 mph passenger-side small overlap tests on seven small SUVs with good driver-side small overlap ratings. Only one of the vehicles, the 2016 Hyundai Tucson, performed at a level corresponding to a good rating, and the others ran the gamut from poor to acceptable.

The results have prompted IIHS to consider instituting a passenger-side rating as part of its Top Safety Pick criteria.

"This is an important aspect of occupant protection that needs more attention," says Becky Mueller, an IIHS senior research engineer and the lead author of the study. "More than 1,600 right-front passengers died in frontal crashes in 2014."

IIHS introduced the small overlap test in 2012, following the success of the moderate overlap front test in spurring automakers to make improvements. While the moderate overlap test involves 40 percent of the width of the vehicle, the small overlap test involves just 25 percent. It is designed to replicate what happens when the front corner of a vehicle collides with another vehicle or an object like a tree or utility pole.

Small overlap crashes pose a challenge because they bypass a typical vehicle's main front structure. Since the test was introduced, 13 manufacturers have made structural changes to 97 vehicles. Of these, nearly three-quarters earned a good rating after the changes.

IIHS conducts its tests for frontal ratings with a driver dummy and with the barrier overlapping the driver side. The reason is simple: Every vehicle on the road has a driver, but there isn't always a passenger riding along.

"It's not surprising that automakers would focus their initial efforts to improve small overlap protection on the side of the vehicle that we conduct the tests on," says David Zuby, IIHS executive vice president and chief research officer. "In fact, we encouraged them to do that in the short term if it meant they could quickly make driver-side improvements to more vehicles. As time goes by, though, we would hope they ensure similar levels of protection on both sides."

The recent passenger-side tests show how big the differences can be. In this group of small SUVs, most didn't perform as well when they were crashed into a barrier on the right side instead of the left. That was even true of models that appeared symmetrical after removing bumper covers and other external components.

"When structural improvements are visible only on the driver side, there are large differences in performance," Mueller says. "But the inverse is not true. Some vehicle structures look the same on both sides, but they don't perform the same. That's why we can't rely on visual analysis but need to monitor this issue and possibly begin rating vehicles for passenger-side protection."

Toyota RAV4 driver sideToyota RAV4 passenger side

The structure of the Toyota RAV4 held up well in the driver-side small overlap test (left). In contrast, intrusion was severe in the passenger-side crash.


The 2015 Toyota RAV4 and the 2014 Nissan Rogue were the only vehicles to appear asymmetrical. In the passenger-side test, the RAV4 was the worst performer. If the Institute issued ratings for passenger-side protection, the RAV4 would earn a poor rating. The Rogue would earn a marginal.

These two vehicles had the highest amount of passenger-side intrusion. Intrusion measures are important because they indicate how well the structure held up; the greater the amount of intrusion, the higher the likelihood of serious injuries.

Maximum intrusion in the passenger-side test was 13 inches more than in the driver-side test for the RAV4 and 10 inches more for the Rogue. The Rogue's door hinge pillar was torn off completely, and the RAV4's door opened. In a real crash, an open door would leave the occupant at risk for ejection.

Two vehicles that appeared symmetrical, the 2014 Subaru Forester and the 2015 Mazda CX-5, also had substantially more intrusion in the passenger-side test than in the driver-side test.

In earlier research, Mueller found that the most common change manufacturers make to improve vehicle structure for small overlap protection is to strengthen the occupant compartment. To do this, they might use a different type of material or add a few millimeters of thickness — changes that can't be discerned from a visual examination. It's likely these types of modifications were made to the Forester and CX-5, but only on the driver side.

The other three vehicles tested had relatively similar structural performance on both sides of the vehicle. The small differences that were observed could have been caused by normal variability in test results. Another factor is that vehicles are to a certain extent inherently asymmetrical. For example, structures to secure the steering wheel and pedals may provide additional bracing around the driver-side toepan, which prevents some intrusion.

In addition to the seven passenger-side small overlap tests, Institute engineers conducted two passenger-side moderate overlap tests to make sure there weren't any differences in performance in that type of crash. One visually symmetrical vehicle, the 2015 Honda CR-V, and one asymmetrical vehicle, the RAV4, were chosen for these tests. There was little difference from the driver-side moderate overlap tests, and both vehicles would receive a good passenger-side moderate overlap rating.

"We conducted the moderate overlap tests as a spot check, and we weren't surprised that both vehicles performed well," Mueller says. "Many of today's models are designed for the global market and are subject to driver-side moderate overlap tests in right-hand-drive countries. With small overlap, there isn't the same incentive for symmetrical design because we're the only organization conducting the test."

IIHS passenger-side small overlap ratings would remedy that situation. The Institute could start such a program next year and make it a requirement for one of its safety awards as early as 2018.

Small overlap front ratings for small SUVs

Driver-side rating Provisional passenger-side rating
2016 Hyundai Tucson
2015 Buick Encore
2015 Honda CR-V
2015 Mazda CX-5
2014 Nissan Rogue
2014 Subaru Forester
2015 Toyota RAV4
GOOD ACCEPTABLE MARGINAL POOR

Small overlap front ratings for small SUVs

2016 Hyundai Tucson

  • Driver-side rating: Good
  • Provisional passenger-side rating: Good

2015 Buick Encore

  • Driver-side rating: Good
  • Provisional passenger-side rating: Acceptable

2015 Honda CR-V

  • Driver-side rating: Good
  • Provisional passenger-side rating: Acceptable

2015 Mazda CX-5

  • Driver-side rating: Good
  • Provisional passenger-side rating: Acceptable

2014 Nissan Rogue

  • Driver-side rating: Good
  • Provisional passenger-side rating: Marginal

2014 Subaru Forester

  • Driver-side rating: Good
  • Provisional passenger-side rating: Marginal

2015 Toyota RAV4

  • Driver-side rating: Good
  • Provisional passenger-side rating: Poor

Save

Read more: Passengers at risk in small overlap crashes

ITS Benefits >> Variable speed limit pilot found to be effective reducing the number of overall crashes.

In May 2013 the Texas State Legislature approved and required a pilot program to evaluate variable speed limits. Variable speed limits were piloted in areas identified as having conditions warranting temporary lower speed limits, including inclement weather conditions, congestion, and construction. Three sites were selected: westbound Loop 1604 in San Antonio, southbound I-35 in Temple, and I-20 in both directions at Ranger Hill in Eastland County.

Over the three month pilot period, there were over 400 activations of temporary speed limits, most commonly for congestion and least commonly for weather. Most activations lasted for less than an hour, but others lasted as long as 10 hours. Speed limits typically changed multiple times per activation.

Benefits

During the variable speed limit pilot in Texas, two safety benefits were observed.

  • Total number of crashes overall was reduced.
  • At two of the three sites there was a reduction in the number of crashes.
  • Crash severity at all pilot sites was reduced.
  • There were no fatal or incapacitating crashes reported at any of the pilot sites during the three month test period.

Read more: ITS Benefits >> Variable speed limit pilot found to be effective reducing the number of overall...

Mercedes-Benz GLE-Class is a Top Safety Pick+

ARLINGTON, Va. — The 2016 Mercedes-Benz GLE-Class, a midsize luxury SUV, earns a superior rating for front crash prevention and qualifies for the Top Safety Pick+ award from the Insurance Institute for Highway Safety.

ARLINGTON, Va. — The 2016 Mercedes-Benz GLE-Class, a midsize luxury SUV, earns a superior rating for front crash prevention and qualifies for the Top Safety Pick+ award from the Insurance Institute for Highway Safety.

An advanced-rated front crash prevention system comes standard on the GLE-Class. When equipped with an additional, optional system called Pre-Safe Brake, the rating rises to superior.

When equipped with the standard system alone, the GLE-Class avoided a collision in the 12 mph IIHS track test. In the 25 mph test, the impact speed was reduced by 12 mph. With the addition of Pre-Safe Brake, the vehicle slowed by an average of 24 mph in the 25 mph test.

The optional system also includes a forward collision warning component that meets National Highway Traffic Safety Administration criteria.

The GLE-Class earns good ratings in the IIHS small overlap front, moderate overlap front, side, roof strength and head restraint tests.

To qualify for Top Safety Pick+, a vehicle must earn good ratings in all five crashworthiness tests and have an available front crash prevention system that earns an advanced or superior rating.

Read more: Mercedes-Benz GLE-Class is a Top Safety Pick+

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