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FY 2017 TRC Projects




Bridge Load Posting Based on Actual Arkansas Truck Traffic   Truck Activity Analysis Using GPS Data
Weight limitations for trucks using Arkansas bridges are calculated using a suite of truck configurations and loadings.  These trucks are used to determine posted bridge load limits as a function of truck axle configuration.  Truck configurations and axle loadings are given in the AASHTO Manual for Bridge Evaluation: SU4 (GVW = 54k), SU5 (GVW = 62 k), SU6 (GVW = 69.5k), SU7 (GVW = 77.5k) and Notional Rating Load (NRL)  (GVW = 80 k).  All of these truck types satisfy the federal bridge formula.  If a bridge is adequate for the NRL loading, cases SU4-7 do not need to be considered for bridge posting loads. The Arkansas Highway and Transportation Department (AHTD) additionally considers CODE 4, CODE 9 and CODE 5 CMV (commercial motor vehicle) gross weights and axle configurations as weight limit posting vehicles.  AHTD uses these CODE CMVs to represent trucks using AR bridges.  However, these truck configurations and weights may be outdated or inappropriate.  For example, the five-axle semi-truck, CODE 5, wheel configuration is overly conservative for many five-axle semi trucks with an outer axle group distance (axle group 2- axle group 5) greater than 16-ft.  As a result, many five-axle semi trucks are currently incorrectly prohibited from using an AHTD Code 5 posted bridge.  Consequently, there is a need to correctly evaluate Arkansas truck traffic so that AHTD bridge engineers can accurately assess bridge weight limit values. Due to the increasing impacts of freight movements on transportation infrastructure, operations, and the economy, planning and decision making bodies must consider freight at every stage of the decision making process. State transportation agencies tasked with forecasting freight movements rely heavily on timely and accurate freight data. Traditional data sources for monitoring truck activity such as the national Vehicle Inventory and Use Survey (VIUS) or Weigh-in-motion (WIM) lack the necessary detail pertaining to travel times, route selection, and time of day travel patterns. Thus it is necessary to evaluate new sources of truck activity data. Truck Global Positioning System (GPS) data, a valuable and recently available data source, can be used to support statewide planning, operations, and management programs. In Florida, GPS data provided by the American Trucking and Research Institute (ATRI) was used to derive freight performance measures, analyze truck trip characteristics, develop origin-destination (OD) tables of statewide freight flows, and evaluate special topics such as re-routing patterns due to incidents. As each state possesses unique and diverse freight movement characteristics, the methods used to analyze and manipulate truck GPS data in one state may not apply well to another state. Arkansas experiences significant levels of pass through freight movements which might require GPS traces to be processed in a different manner than those developed for Florida which sees a relatively higher number of originating and terminating freight movements. Thus it is necessary to evaluate and compare the appropriateness of previously developed methodologies for analyzing truck GPS data within the context of the freight patterns observed in Arkansas. This research would determine whether GPS data can meet statewide planning needs while providing valuable insight into truck movements in Arkansas.
Final Report




School Bus Stops Safety    

Transporting students safely is the main priority for school transportation directors, bus drivers, and other essential personnel involved in getting students to school. The primary task for school transportation directors is planning bus routes, which can impact student safety. These bus stop placements not only dictate the routes students travel between home and the stop, but also environmental conditions in which students are subjected while waiting for the bus. According to a 2015 FHWA/NHTSA study, from 2004 to 2013, 327 school-age children died in school-transportation related crashes with highest numbers during the hours of 7AM to 8AM and 3PM to 4PM. Beginning in October 2012, Safe Routes to School (SRTS) activities was eligible to compete for funding alongside other programs under MAP-21. The current SRTS legislation provides $612 million to the states to distribute to communities for providing safer child travel to school by bike or on foot. The intent of the funding is primarily (70 to 90 %) for infrastructure improvements, but is also intended to provide 10 to 30% for safety education and enforcement. Possible suggestions by working with school transportation directors could be: 1) Providing safer “Student Pickup Zones,” installing raised sidewalks and loading/unloading areas within ROWs. 2) Install centralized bus stops in the ROW to reduce the number of vehicle stops. 3) Install flashing signs for areas with high potential for accidents, such as multiple curves.