A Traffic Bottleneck is defined by Federal Highway Administration (FHWA) as a localized constriction of traffic flow, often on a highway segment that experiences reduced speeds and inherent delays, due to recurring operational influence or a nonrecurring impacting event. Further, a bottleneck is an area of poor Level of Service (LOS) or high Volume to Capacity (V/C) ratio which ends at a point, has a recurring cause, and, maybe most importantly, exhibits a return to free flow speeds after the bottleneck end point. FHWA further indicates that “a bottleneck has congestion, but congestion is often more than a bottleneck”, citing an example of a wide highway with a narrow bridge that restricts traffic flow on a regular basis. It should also be noted for differentiation purposes that a road that has a high V/C or poor LOS for an extended length, or for its entire length, is not a bottleneck, but rather is considered a chronically congested roadway, where demand routinely exceeds capacity.
The Transportation Management Systems, along with their respective GIS components, maintained by CMRPC (congestion, pavement, safety, freight planning, public transit planning) and MassDOT (bridge and pavement) have been referenced in attempting to determine the “root causes” of recurring Traffic Bottleneck locations. Building on the planning agency’s extensive knowledge of the region’s federal-aid highway system, the Localized Bottleneck Reduction Program considers all roadway segments and major intersections in the region’s federal-aid highway system, with an emphasis on CMMPO indentified “Vital Links”, or core federal-aid roadways.
After reviewing the Localized Bottleneck Reduction Program analysis results for a given location, suggested improvement options aimed at reducing and eliminating the identified Traffic Bottlenecks were formulated for consideration by MassDOT and the host communities. Based on FHWA/FTA’s call for “low-cost countermeasures” or solutions, a range of improvement options were considered, with the primary intent of identifying workable, low-cost Transportation System Management (TSM) improvements eligible for federal-aid funding. TSM improvements are “low-cost” by nature, ranging from $100,000 to $500,000, and can often be implemented within the existing right-of-way. The results of the Localized Bottleneck Reduction Program may lead to the development of projects funded through the CMMPO Transportation Improvement Program (TIP). These potential improvement projects would need to compete with others deemed eligible for programming on the TIP’s highway-related project listing.
Since 2014 the Bottleneck Reduction program has been a part of the Congestion Management Process CMP program for current information on bottlenecks, please refer to the most current CMP progress report.
