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Future Road Safety

Forecasting Road Freight Safety

Based on crash records, we know which roads are not safe today. However, attempting to predict which roads, intersections and bridges will become concerns for safety in the future is not something transportation professionals have considered until very recently. In the past year, OKI has conducted a crash data analysis for all vehicles to help identify key road segments and intersections across the region that exhibit higher than average future safety concerns. For potential application to this freight plan, OKI staff expanded their initial data analysis of all vehicles to examine future truck safety conditions.  

Truck Crash Analysis Methodology

OKI’s analysis looked at a variety of predictor variables, including annual average daily traffic (AADT); truck AADT; and road geometry (number and width of lanes, urban versus rural environments, road segment length, etc.) to determine potential impacts that could lead to truck-related crashes. Additional predictors considered were sinuosity (an estimate of the curvature of a segment), average slope of a segment, and outer shoulder width.

Using safety performance functions, OKI predicted the number of truck crashes on road segments in the region for 2016 to 2020; estimated the expected crashes for 2016 to 2020; computed the excess expected crashes, which is the difference between the expected crashes and the predicted crashes for 2016 to 2020. We then used the functions to predict truck crashes for years 2046 to 2050, based on projected traffic volumes from the OKI Travel Demand Model. In most cases, the expected traffic volume will increase in the future, as will the expected truck volume. OKI assumed that there were no significant changes to the road system, truck safety systems, or driver behavior. 

Key Truck Crash Analysis Findings

OKI’s analysis found that total AADT and truck AADT were the most significant predictors of truck crashes. The median changes in predicted truck crashes between 2016-2020 and 2046-2050 are at or near-zero for many segment types. For two- and four-lane highways, there is a much larger increase in predicted truck crashes. This is due, in part, to the much higher traffic volume these roadways experience compared to other types of segments. About 94% of segments are predicted to have at most only one crash over a five-year period.

Overall, the findings showed that the number of truck crashes predicted for 2046 to 2050 is higher than the numbers predicted and observed in 2016 to 2020. This increase is not distributed evenly, so some areas will be of higher concern than others. Road segments with high-excess expected crashes in 2016 to 2020 — that also have a predicted increase in truck crashes for 2046 to 2050 — merit greater attention, since they are already experiencing significantly more crashes than predicted in 2016 to 2020. These are mainly seen on interstate highways. The top ten segments of concern are shown in the table below.

The map uses three colors to identify roadway segments across the OKI region that have excess expected crashes, which is the difference between the expected crashes and the predicted crashes for the years 2016 to 2020, between the values of 1 to 3, 3 to 7, and more than 7.
OKI staff analysis took the Excess Expected Truck Crash location values for years 2016 to 2020 and then used the functions to predict truck crashes for future years 2046 to 2050, based on projected traffic volumes from the OKI Travel Demand Model. The result is that this map helps identify the most unsafe potential future roadway segments for trucks by focusing on those locations with both high excess expected crashes and an increase in predicted crashes.

Undesignated Truck Parking Strikes

Truck parking has been a high concern in Boone County for several years due to the growth of e-commerce and air-to-truck cargo deliveries. Recent data shows that Warren and Butler counties, especially along the I-71 and I-75 corridors, are experiencing greater occurrences of undesignated truck parking. Trucks parked on shoulders and interstate ramps present safety concerns both for truck drivers and the traveling public.

In addition to parking, if trucks need to refuel — whether diesel, electric charge or hydrogen — a stop may be needed between their origin and destination. Queuing for a refueling stop, if facility demand surpasses capacity, may result in trucks parked along roadways temporarily (less than hour) to wait their turn. This queuing effect would impede traffic flow and safety of other vehicles.

To help identify potential areas across the region where undesignated truck parking strikes may be a more frequent or larger concern, OKI conducted a data analysis using a 2021 sampling of truck Global Positioning System (GPS) information obtained from the American Transportation Research Institute (ATRI) and 2016 to 2021 actual truck involved crash records provided by the Ohio, Kentucky, and Indiana state departments of transportation.

Since crash reporting varies widely between the three states, a direct link of truck involved crashes to trucks parked in undesignated locations is not feasible. For example, only the State of Ohio indicates in their crash records whether a parked vehicle was involved and yet reports do not indicate which vehicle (truck or passenger vehicle) was parked. Therefore, OKI’s analysis must be viewed with this limitation in mind.

To assist in screening crash data for events that could potentially be associated with a undesignated-parked truck, OKI staff only included crash records coded as rear end, sideswipe – same direction, parked vehicle, improper lane usage, and other/unknown.

The results of this analysis are visualized in OKI’s Truck Freight interactive map. Taking analysis’ limitations into consideration, a few areas, known for high truck traffic, do appear in the map as potential locations exhibiting high undesignated truck parking occurrences and truck involved crashes. These areas call for a closer look and further study to determine whether undesignated truck crashes pose a greater threat than other locations across the OKI region:

  • I-71/75 corridor in Boone County – includes the north- and southbound rest areas
  • KY 18/US 42 area in Florence, Kentucky
  • Queensgate section of I-75 in Cincinnati, Ohio
  • Ivorydale area at I-75 and the SR 562 (Norwood Lateral) just north of St. Bernard, Ohio
  • SR 747 just north of I-275 in Springdale, Ohio
  • I-75 in Butler County, Liberty Township just south of SR 63 – includes the north- and southbound rest areas
  • Broad segment of I-75 in Warren County near the county line (extra consideration should be taken with this area as it may be due to reporting limitations of ATRI’s GPS truck data)

One thing is certain, without addressing the lack of sufficient truck parking and queuing, with the projected increases in truck volume, the occurrences of truck involved crashes will only continue to rise. While advancements are being made in developing automated trucks, adoption of fully automated vehicles, capable of traveling safely from origin to destination on all roads in urbanized areas, is still decades away. In the future, with the ability to remove humans from the vehicle entirely, fully automated trucks would eliminate the need for long- and short-term parking. With no driver, federal Hours of Service (HOS) rules — which today require drivers to take mandatory breaks — will not apply. Automated trucks can eliminate the need for short-term parking, as well, by automatically adapting truck speed to account for traffic congestion, travel time, and dock readiness to achieve an efficient and synchronized arrival. 

Statewide Truck Parking Analyses

In 2022, the Ohio Department of Transportation (ODOT) completed a statewide truck parking study that reported related deficiencies in the Cincinnati region. The mega-cluster identified by ODOT includes high-priority, undesignated truck parking clusters in the downtown, which area due to last-mile and urban delivery parking issues; and along I-71 and I-75, which are caused by supply-demand imbalances at truck parking facilities. ODOT’s 2019 analysis of truck stops showed that about 6,790 trucks parked for an average of about four hours in undesignated locations in this mega-cluster. ODOT connected these truck parking issues to 20 truck-related crashes. The peak number of undesignated truck parking in the Cincinnati mega cluster is between 11 p.m. and 7 a.m. In this cluster, about 65% of trucks parked on undesignated locations stopped for short breaks of fewer than 3 hours, while 27% parked for longer HOS compliance breaks of more than 8 hours.

The Kentucky Transportation Cabinet (KYTC) conducted a truck parking study in 2022. As part of this study, the Interstate 71/75 northbound and southbound rest areas in Boone County were determined to be among the state’s highest priority locations for truck parking concern and potential expansion. As a result, KYTC did a deeper analysis and planning effort of these rest areas. Their findings revealed that the northbound rest area has a capacity of 53 truck parking spaces with a peak demand for 106; and the southbound rest area has a capacity of 67 truck parking spaces with a peak demand for 150. With demand far exceeding capacity, the daily occurrence of trucks parking along the rest areas’ exit and entrance ramps is apparent. In 2023, KYTC is extending funding so that preliminary engineering and design for truck parking expansion can be conducted for these two, high-demand rest areas in Northern Kentucky.

Technologies Improving Truck Parking Safety

Technology began to be used several years ago to communicate the availability of safe, designated truck parking. Depending upon the level of truck parking technology, occupancy detection can be collected through closed-circuit television (CCTV) cameras, in-ground sensors, or microwave sensors. These technologies can also track the number of trucks entering and exiting a parking facility to estimate parking space availability. Real-time parking information is disseminated to truck drivers using in-vehicle radios, dynamic message signs, mobile apps, websites, or a combination. Field tests indicate these systems are more than 90% accurate.

Example of Truck Parking Availability Deployment

In 2015, the Ohio Department of Transportation (ODOT) and Kentucky Transportation Cabinet (KYTC), in partnership with six other Mid America Association of State Transportation Officials (MAASTO) member states, were awarded a $25 million federal Transportation Investment Generating Economic Recovery (TIGER) grant. This federal funding source is now called the Rebuilding American Infrastructure with Sustainability and Equity (RAISE) Transportation Discretionary Grant program. An additional $3.6 million in state funding was provided for this multi-state project to launch a real-time parking availability information system for commercial drivers to improve the safety and efficiency of the region’s freight network. The project is called the Regional Truck Parking Information Management System or TPIMS for short. Through dynamic roadside signs, information is displayed to truckers along major interstate routes.

In the OKI region, the TPIMS program provides information on truck parking availability at four public rest areas located on Interstate 75:

  • ODOT has two dynamic message signs communicating the availability of truck parking at the I-75 rest areas at mile marker 27 in Butler County, Liberty Township just south of the SR 63 interchange. The southbound TPIMS message sign is installed at mile marker 38.7 (latitude: 563373, longitude: -84.269574) in Warren County and reports on the availability of I-75 southbound rest area’s 20 truck parking spots. The northbound TPIMS message sign is installed at mile marker 22.8 (latitude: 39.35419, longitude: -84.37317) in Butler County and reports on the availability of I-75 northbound rest area’s 20 truck parking spots.
  • KYTC has two message signs that digitally display the number of truck spaces open at the I-71/75 rest areas in Boone County between the KY 536 (Mt Zion Road) and KY 338 (Richwood Road) interchanges. The southbound TPIMS message sign is installed at milepost 177.4 (latitude: 9457, longitude: -84.6335) and reports on the availability of I-75 southbound rest area’s 67 truck parking spots. The northbound TPIMS message sign is installed at milepost 170.8 (latitude: 38.8513, longitude: -84.6218) and reports on the availability of I-75 northbound rest area’s 53 truck parking spots.

In addition, KYTC has three cameras installed in Boone County as part of the TPIMS program at the following locations:

  • I-71 southbound, milepost 75 (latitude: 8647, longitude: -84.6491)
  • I-75 northbound, milepost 177 (latitude: 9357, longitude: -84.6298)
  • I-75 southbound, milepost 177 (latitude: 941, longitude: -84.6341)


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