Congestion Management Process (CMP)
Traffic congestion is an increasingly common condition experienced by users of the transportation system. Congestion’s resulting loss of time, increased fuel consumption, and added air pollution have far-reaching social, financial, and environmental impacts beyond the movement of people and goods. The Louisville area’s quality of life and economic competitiveness are closely related to the degree to which the transportation system is able to provide an acceptable level of mobility. Short-term consequences of congestion include changes in choice of mode, time of day, and frequency of travel. Long-term consequences of congestion might include its influence on land use and development patterns, where people choose to live and work, and where businesses choose to locate.
Businesses pass along to consumers the costs of increased travel time and operating costs which result from congestion. An efficient transportation system is reflected by the ability to travel with a minimum of delay. Factors influencing delay are the capacity of the system, operational characteristics, and the amount of demand during a given period of time. According to the Federal Highway Administration’s Traffic Congestion and Reliability: Trends and Advanced Strategies for Congestion Mitigation report, congestion is defined as “…an excess of vehicles on a portion of roadway at a particular time resulting in speeds that are slower—sometimes much slower— than normal or free flow speeds” and is a result of the combined interaction of these factors. The various causes of congestion, sometimes occurring in combinations, have been categorized as follows:
- Bottlenecks or Choke Points– Usually a reduction in the physical capacity of the roadway (the number and width of lanes and shoulders; merge areas at interchange ramps; and roadway alignment (grades and curves).
Incidents –Events such as vehicular crashes, breakdowns, and debris in travel lanes are the most common forms of incidents. As part of the process to help manage incidents, TRIMARC has instituted a notification service that will help to let anyone who signs up for the service know of major incidents and road closures. The website is the NET (Notify Every Truck). This website notifcation is free.
Construction Work Zones – Locations where construction activities on or near the roadway result in reductions in posted speed limits, the number or width of travel lanes, lane "shifts," lane diversions, reduction, or elimination of shoulders, and even temporary roadway closures.
Inclement Weather – Rain, snow, ice, wind, or other environmental conditions that can lead to changes in driver behavior that affect traffic flow.
Traffic Control Devices – Intermittent disruption of traffic flow by control devices, such as railroad grade crossings and poorly timed signals, also contribute to congestion and travel time variability.
- Special Events – Are a special case of demand fluctuations whereby traffic flow in the vicinity of the event will be radically different from "typical" patterns. Special events occasionally cause "surges" in traffic demand that overwhelm the system.
Fluctuations in Normal Traffic – Day-to-day variability in demand leads to some days having higher traffic volumes than others. Varying demand volumes superimposed on a system with fixed capacity also results in variable (i.e., unreliable) travel times.
For analysis purposes, the above causes can be classified as either recurring congestion or non-recurring congestion. The former typically occurs during weekday morning and afternoon peak periods, when most people go to work and return home at around the same time, consequently reducing traffic speed and increasing personal commuting time. Non-recurring congestion results from random conditions, such as: crashes, construction work zones, inclement weather and special events. Because of the random nature of these events and conditions, non-recurring congestion is more difficult to predict and mitigate. The ability to identify and measure different types of congestion, including the non-recurrent type, is key to developing appropriate solutions.
With Horizon 2030: The Long-Range Transportation Plan for the Louisville (KY-IN) Metropolitan Planning Area, efforts were made to more fully and formally integrate the consideration of congestion into the transportation plan development process. Several procedures were instituted which utilized components of the Congestion Management Process to identify and quantify congestion problems, generate mitigation measures as proposed projects, and establish funding priorities for projects selected for the plan.
Congestion Management Process Overview for Louisville (KY-IN) Metropolitan Planning Area
PDF, 7.8 MB
Map of the Louisville (KY-IN) MPA Congestion Management Process Network
PDF, 1.9 MB (A smaller version of the map is also available from the Maps page.)
Map of the Louisville (KY-IN) MPA State of the System 2008 Freeway Level of Service
PDF, 5.4 MB (A smaller version of the map is also available from the Maps page.)
Map of a Comparison of the Louisville (KY-IN) MPA State of the System Freeway Level of Service: 2001, 2005, and 2008
PDF, 9.1 MB
TRIMARC -Incident Management and Itelligent Transportation for the Metropolitan Planning Area
Intelligent Transportation Systems