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The Increasing Need for North Carolina's Surface Transportation System to Accommodate Larger and Larger Vehicles

(Any opinions stated or implied in the material below are those of the primary author, Dr. Ron Hughes, of the NCSU Institute for Transportation Research and Education and not the NC Department of Transportation or the NC State Highway Patrol)

ITRE's commercial vehicle safety and security research group continues to support NC Highway Patrol's Motor Carrier Enforcement efforts to inc rease CMV awareness within other law enforcement agencies across the state of North Carolina. The material included here is a presentation made by Dr. Hughes as part of the CMV Awareness Training provided to Troops D and E and to those agencies identified as playing a major role in crash reporting in those troop areas. CMV Awareness Slides for Troops D and E.prior to AG ruling.ppt (PPT: 7.15 MB). A large component of this 'awareness' training focuses on the timeliness and accuracy of crash reporting and its relationship to FMCSA initiatives like CVISN (Commercial Vehicle Information Systems and Networks). The presentations also emphasize the importance of CMV size and weight enforcement.

The CMV Awareness presentation to Troops D and E was made prior to a recent State Attorney General's ruling regarding 53ft trailer access to roadways in the state STAA-Truck-Crash-Data- Final-Report.pdf (PDF:6.5MB). It was also presented prior to efforts on the part of ITRE, the NCSHP, and the NCDOT to observe directly the impact of operating 53ft tractor trailers on roads added to the Truck Network as part of the Attorney General's ruling Field Observations of 53 ft Semitrailer on New STAA Routes.pdf (PDF: 5MB). To many, the operation of vehicles whose width and/or overall length exceeds their ability to remain between the center and edge lines of their own travel lane represents a serious safety concern. Irrespective of whether collisions with such vehicles result in fatalities or serious injuries they can also contribute significantly to congestion and delay associated with their removal from the roadway. These delays can also be a serious impediment to the response times of emergency medical services attempting to reach persons requiring immediate medical attention or transport. Opening up access to large and heavy commercial vehicles without regard to their impact on the infrastructure (pavement, posted bridges, etc.) also increases the rate of roadway deterioration and the cost of repair/maintenance.

In April 2008, ITRE was requested to provide the NCSHP with data from NCDOT's Traffic Engineering Accident Analysis System (TEAAS) regarding the crash involvement of vehicles towing boat trailers. These data are provided below Boat-Trailer Crash data 2005-2007.ppt (ppt, 87 KB). The request was prompted by increased pressure from the owners of large boats and their freedom to move these vessels (increasingly over the present 102" width requirement) without incurring the constraints of permits required for their movement. Whether vessels over 102 inches in width (8' 6") are used in commerce or for recreational use only, their movement on the highway is currently restricted (by permit) to operation during daylight hours only. No movement is allowed on Sundays and certain holidays (as stated in NCDOT Oversize and Overweight Permit Handbook available from the NCDOT Oversize/Overweight Permit Office in Raleigh, N.C.

One should not attempt to infer from data showing that fewer than five percent of all such crashes involved trailers wider the allowed 102 inches that there is a relatively low likelihood of such configurations being involved in crashes. One cannot tell from these limited (crash) data anything about the relative crash risk of loads of this size. Aside from the 'permitting' issue it is clear that a more important issue is whether the vehicle towing a vessel of this size is properly equipped and licensed for the increased combined weight of the towing vehicle and the load being towed.

Is there a trend here?

The ruling by the State Attorney General's office was prompted by pleas from the farming community as well as retailers for increased access for longer (53 ft) vehicles, which each group claimed was increasing becoming the industry standard. Demands from the boating community and boat builders' industry in the state was in part a 'length' issue, but in larger part, based upon the premise (of the boat owners, etc.) that boats should not be held to the same restrictions as commercial motor vehicles . . . but rather, as 'recreational vehicles,' they should be given special treatment.

ITRE has 'no horse in this race.' ITRE does not make public policy or draft legislation. ITRE does, however, feel obliged to render its opinion when it comes to highway safety. It is our opinion that any vehicle whose width exceeds that of the travel lane in which it operates is 'too wide.' Being too wide for existing conditions does not necessarily mean that it should be prohibited from those routes, but rather that special provisions (e.g., a permit, required escorts, time of day restrictions, etc.) may be needed to ensure its safe passage and that of others who share the road while it is en route.

Long (over length) vehicles, even when they do not exceed the restrictions imposed by the STAA legislation, have unique operating characteristics (e.g., off tracking) that may cause them to intrude into the on coming traffic lane or to experience intrusions over the edge line of the roadway. The report detailing the joint observations by the NCSHP, NCDOT, and ITRE of 53 ft trailer operations in the western part of the state (on sections of US-64 and US-74A) provides diagrams from the AASHTO 'Green Book' on the minimum turning requirements of longer vehicles – specifically the minimum swept distance requirement of these vehicles when negotiating turns. It was clear from these limited observations that the minimum swept path distance of 53 ft trailers often exceeded the width of the paved roadway surface.

Longer and wider vehicles (commercial and recreational alike), as well as heavier vehicles, are becoming more commonplace on our roads. This is a trend that seriously threatens the continued success of North Carolina over the past ten years in reducing the number of CMV-involved fatalities in the state. It is also a trend that threatens to worsen congestion in our already over-congested urban areas. Longer, wider, and heavier vehicles also put a serious strain on the state's infrastructure and on the state's ability to maintain that which is already has in place.

There is a serious need for joint action on the part of the commercial vehicle industry, state departments of transportation, legislative officials, and enforcement to devise effective long-term strategies for dealing with theses trends. Using enforcement and legislation to restrict access as a means of prolonging the life of an already limited infrastructure is probably not the best answer. Neither is it prudent to think that the state DOT and taxpayers can overnight bring all roads up to interstate design standards. It is important that effective strategies for dealing with long term surface transportation needs be addressed in current state government planning efforts directed at a strategic statewide logistics plan. Some of ITRE's efforts to address the growing problem presented by increased commercial motor vehicle presence are outlined in a recent document