Tag Archives: trucks

New performance measures identify truck delays and bottlenecks

A new freight transportation study takes the next step in lessening traffic bottlenecks by pinpointing location and time of recurrent delays.

Freight transportation provides significant contribution to our nation’s economy. Reliable and accessible freight network enables business in the Twin Cities to be more competitive in the Upper Midwest region. Accurate and reliable freight data on freight activity is essential for freight planning, forecasting and decision making on infrastructure investment.

Researchers used detailed and specific data sets as tools to investigate freight truck mobility, reliability and extent of congestion delays on Twin Cities metropolitan area corridors. Precise locations and times of recurrent delays will help to mitigate future traffic bottlenecks.

“This research provided tools and metrics with new levels of precision concerning truck congestion. The results will allow us to take the next steps toward future investment in addressing freight bottlenecks,” said Andrew Andrusko, Principal Transportation Planner, MnDOT Office of Freight and Commercial Vehicle Operations.

What Was the Need?

The corridors of the Twin Cities metropolitan area (TCMA) provide a freight transportation network that allows regional businesses to be competitive in the Upper Midwest. However, traffic volumes on many of these roadways are facing overcapacity during peak travel periods. Heavy truck traffic is only expected to increase, and delays will continue to disrupt freight schedules.

A 2013 study by MnDOT and the Metropolitan Council suggested the need to identify when and where truck congestion and bottlenecks developed in the TCMA. Previous research funded by MnDOT examined heavy truck movement along 38 Twin Cities freight corridors. Researchers created freight mobility and reliability measures, and worked to identify significant bottlenecks. Further research was needed to extract more precise data to better understand TCMA freight traffic congestion.

2018-15-p2-image
The top five congested AM and PM peak corridors in the TCMA are listed above with the delay hours for each period. The large delay hours arise from heavy truck volume and speeds far below base free-flow speeds.

What Was Our Goal?

The aim of this project was to combine data from the U.S. DOT National Performance Management Research Data Set (NPMRDS) with information from other sources to build on the previous study’s analyses of mobility, reliability and delay along key TCMA freight corridors. New performance measures would more clearly identify the extent of system impediments for freight vehicles during peak periods in selected corridors, allowing researchers to identify causes and recommend mitigation strategies.

What Did We Do?

Researchers worked with stakeholders to prioritize a list of TCMA freight corridors with NPMRDS data coverage. The NPMRDS includes travel time data from probe vehicles at five-minute intervals for all National Highway System facilities. The travel times are reported based upon Traffic Message Channel (TMC) segments with link lengths varying from less than 1 mile to several miles. Researchers worked with 24 months of NPMRDS data from the selected corridors.

Because of varying TMC segment lengths, researchers used geographic information system (GIS)–based data to georeference the NPMRDS data to relevant maps. Combining these with average travel time data from passenger and freight vehicles, researchers used their data analysis framework to generate measures of truck mobility, reliability and delay at the corridor level.

A truck mobility analysis of all the selected corridors was performed using the truck-to- ar travel time ratio (TTR) for each TMC segment of each five-minute interval computed in AM (6-10 a.m.), midday (10 a.m.-4 p.m.) and PM (4-8 p.m.) peak periods using the 24- month NPMRDS data. A TTR of 1 describes a truck and a car traveling a distance in the same amount of time. On average, trucks are known to travel 10 percent slower than cars on freeways: a TTR of 1.1. A truck traveling 20 percent slower would have a TTR of 1.2.

Reliability measures evaluated the truck travel time reliability. Researchers computed truck delay during rush hour on the GIS network by fusing truck volumes, posted speed limit and NPMRDS data.

Researchers computed a truck congestion measure by comparing truck travel time with the target travel time in each TMC segment, which provided a measure of delay (in lost hours) at the segment and corridor level.

What Did We Learn?

The truck mobility analysis revealed that roadways with intersections have a higher TTR. Trucks on U.S. and Interstate highways take about 10 percent longer to travel the same distance as cars: TTR 1.1. On state highways, the TTR reaches 1.2 and 1.4 in the AM and PM peak periods, respectively. On county roads, trucks slow considerably: midday TTR is 1.5 and spikes to 1.7 and 1.9 in the AM and PM peak periods. Intersections in a TMC segment and delays at signalized intersections could have caused the TTR increases.

All reliability measures indicated that truck travel time in the PM peak period is less reliable than in the AM peak period. Similar to the TTR measure, roadways with signalized or unsignalized intersections were less reliable for truck traffic than freeways.

Truck congestion and delay measures revealed that the top five TCMA corridors with significant congestion had an average delay of over 3,000 hours in the AM and PM peak periods, with the PM delays notably greater. Also, in the AM peak period, eight additional interchanges had average delays of over 300 hours per mile. In the PM peak period, nine interchanges and eight segments showed significant congestion.

The top six TMC noninterchange segments exhibiting recurring PM peak period delays on average weekdays had delays ranging from 495 hours to 570 hours per mile.

Insufficient capacity, increasing demand, roadway geometry and density of weaving points (on-and off-ramps) were considered key causes of delay among these six bottlenecks.

What’s Next?

NCHRP Research Report 854, Guide for Identifying, Classifying, Evaluating and Mitigating Truck Freight Bottlenecks, provides guidelines for identifying, classifying, evaluating and mitigating truck bottlenecks. Follow-up research by MnDOT could potentially leverage this project’s effort with the NCHRP guidelines to develop mitigation strategies.

This post pertains to Report 2018-15, “Measure of Truck Delay and Reliability at the Corridor Level, published April 2018.

 

MnDOT Explores the Use of a Unified Permitting Process for Oversize/Overweight Loads

Researchers produced a proof-of-concept for developing a one-stop permitting process that would allow commercial haulers to plan a travel route and secure all required permits from a single source. MnDOT is working to develop a first-of-its-kind, unified permitting process to consolidate the requirements of every jurisdiction in the state into a single, quick-response platform that meets the needs of haulers.

“From a hauler’s perspective, the permitting process can be very cumbersome. Each agency’s application is different as are the general provisions that haulers need to follow,” said Renae Kuehl, Senior Associate, SRF Consulting Group, Inc.

“As carriers, we’re trying to do our due diligence in getting permits. But the current process can lead to significant safety and legal risks,” said Richard Johnson, Transportation Manager, Tiller Corporation.

What Was the Need?

Hauling oversize or overweight freight on Minnesota’s roadway system—highways, county roads, township roads and city streets—requires approval by each governing authority along the route. Roadway managers must review hauler travel plans to make sure size and weight limits for vehicles and loads will not endanger roadway facilities, hauler equipment and personnel before issuing the over-size or overweight permit.

Any single hauling route may require permits from multiple roadway authorities, each with different application procedures and response times. Some governing bodies, MnDOT among them, issue these permits online and can turn them around in minutes. Other agencies issue permits by mail, fax or email, which can take several days.

Haulers, however, may not have time to wait for a permit. If equipment breaks down at a loading site, for example, replacement equipment is needed immediately to meet contract deadlines and avoid paying labor costs for idle workers. A construction emergency may also demand large equipment be towed to a site. In situations like these, haulers often make the trip without appropriate permitting, accepting the legal and safety risks.

What Was Our Goal?

To simplify the permitting process, Minnesota local agencies would like to develop an online permitting application process that would allow permit-seekers to determine routes based on their vehicle and load size, and secure all necessary permits at one time. This research, the first phase of a multiphase study, aimed to determine the feasibility of a one-stop, unified permitting process by studying its technological and operational needs and gathering input from various stakeholders.

What Did We Do?

Investigators worked with the Technical Advisory Panel (TAP) and a group of policy experts from county and state agencies, commercial haulers and consultants to identify audiences with a stake in a unified permitting process. During meetings in northern Minnesota and in the Twin Cities area, investigators and TAP members met with key stakeholders: haulers and representatives from industry organizations; seven MnDOT offices (including Freight and Commercial Vehicle Operations, Information Technology, Maintenance and Geospatial Information); Minnesota counties; the City of Duluth; the Duluth-Superior Metropolitan Interstate Council; Minnesota State Patrol; the State Patrol Commercial Vehicle Section; and a county sheriff’s office.

The research team identified the challenges and needs of each stakeholder and organized the concerns according to policy, process and technology. Then they explored solutions that would allow the development of a one-stop permitting process.

What Did We Learn?

Researchers determined that a unified permitting process is feasible. Policy issues include the need to standardize general provisions statewide, such as travel hours, insurance requirements and warning devices such as flagging needs. For example, currently the color of flags and lettering on banners vary from jurisdiction to jurisdiction; well-framed general provisions could make these requirements more uniform to serve multiple jurisdictions. The information required by each governing authority in its permit applications could also be normalized.

Process issues were about workflow. More than 80 percent of hauler requests are repeat-able: A commercial haul may be run on the same route with the same-size load three times a month for four months and may not require a full reapplication each time. Some agencies rely on paper, fax or emails to receive permit requests; others purchase permit-ting software; still others build their own software. These systems could be made more uniform so they could interact and share information among agencies.

Technology issues called for an interoperable system that could bring together geographic information system (GIS) capabilities and regulatory data that could be both received and shared. Mapping data could identify each permit required along a route being developed, and a portal could allow agencies to share information as well as allow permit-seekers to enter information and retrieve permits themselves. A portal could also integrate different software packages while offering information like Minnesota’s Gopher State One Call digging hotline.

What’s Next?

In Phase II of this project, which has already begun, researchers will develop a pilot portal that allows users to create route plans, identify permits needed and apply for all permits in one action. Investigators will test the platform with a three-county group. If this effort is successful, researchers will build a unified permitting process for use within all jurisdictions in Minnesota.

MnDOT is also enhancing its software for handling oversize/overweight permits and carrier credentials. Transportation Research Synthesis 1704 surveyed state agencies about current offerings.


This post pertains to the LRRB-produced Report 2017-26, “Oversize/Overweight Vehicle Unified Permitting Process (UPP) Phase I,” published August 2017. 

New Tool Measures Impact of Heavy Trucks

A new tool developed by the Local Road Research Board helps cities and counties assess how much increased heavy vehicle traffic affects local roads.

Researchers created an analysis method and corresponding spreadsheet tool that city and county engineers can use to calculate the impact of heavy vehicles on asphalt roads beyond what was planned in the original pavement design.

The information will help agencies optimize services, such as garbage collection, for the least amount of damage. It will also help agencies better plan roads in new developments, as well as redesign existing roads that are nearing the end of their lives.

Lack of Data

Heavy trucks cause local roads to deteriorate more quickly than passenger vehicles, but it is challenging to quantify the impacts, especially for areas where traffic was not forecast at the time a road was designed.

Many local engineers in Minnesota have requested information about the impact of heavy vehicles in light of new construction, commercial distribution facilities and hauling routes. This information is needed to assist in local road planning and maintenance.

Two Methods

In a newly completed study, investigators developed two methods for calculating heavy vehicle impact:

  • Calculate the additional bituminous material (and associated costs) that would have been required to construct the pavement had the heavy truck traffic been predicted when the pavement was designed.
  • Calculate the portion of a pavement’s design life, measured in equivalent single-axle loads (ESALs), consumed by unanticipated vehicles.

“Before this project, there wasn’t an easy way for an engineer to determine how much a specific truck was going to decrease the life of a road,” said  Deb Heiser, Engineering Director, City of St. Louis Park.

Whereas previous research has calculated the impact of extremely heavy vehicles over the short-term (typically the course of a construction project), this project calculates the impact of long-term increases in traffic from vehicles that are heavy, but still mostly within normal legal weight limits.

The tool can be used for a single street segment or an entire road network. Users can also compare current situations with proposed ones to evaluate the impact of potential changes in heavy traffic levels.

Related Resources

Parking availability system takes aim at truck driver fatigue

MnDOT, in partnership with the Federal Highway Administration, is test-deploying a high-tech system to help combat drowsy driving and keep truck drivers in compliance with federal hours-of-service regulations.

Developed by researchers at the University of Minnesota, the prototype system lets  drivers know when parking spaces are available at rest stops ahead. It has been deployed at several locations along the heavily traveled I-94 corridor between Minneapolis and St. Cloud.

From today’s MnDOT news release:

ST. PAUL, Minn. – New technology along the I-94 corridor west and northwest of the Twin Cities is helping truckers find safe places to park. Three Minnesota Department of Transportation rest areas are now equipped with automated truck stop management systems that tell truck drivers when parking spaces are available.

The technology will improve safety, lead to better trip and operations management by drivers and carriers and help MnDOT and private truck stop owners manage their facilities more effectively, according to John Tompkins, MnDOT project manager.

“So far, the results have been positive. We’ve had 95 percent accuracy in determining the availability of spaces,” he said.

Federal hours of service rules require truck drivers to stop and rest after 11 hours of driving. Tompkins said if drivers continue to drive beyond 11 hours, they could become fatigued and be forced to park in unsafe locations such as freeway ramps. They could also face legal penalties.

The problem of truck driver fatigue recently took the national spotlight when an allegedly drowsy driver slammed his semitrailer into a limousine carrying actor-comedian Tracy Morgan and six others. One passenger died in the crash.

The parking availability project is led by MnDOT Freight Project Manager John Tompkins and University of Minnesota professor Nikolaos Papanikolopoulos. MnDOT Research Services & Library produced the video above, which demonstrates the system in action. You can learn more about the project on the Center for Transportation Studies website.