VII. Congestion Management



Within a transportation management area, the transportation planning process under this section shall include a congestion management system that provides for effective management of new and existing transportation facilities eligible for funding under this title and chapter 53 of title 49 through the use of travel demand reduction and operational management strategies.  23 U.S.C. 134 (i)(3)


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he CDTC adopted its Congestion Management System (CMS) in December 1995, building upon its 1993 report entitled Critical Congestion Corridors in the Capital District.  Congestion mitigation is directly related to CDTC’s New Visions goals concerning mobility, wherein mobility is best maintained by providing for convenient travel while reducing inefficient travel behavior.  The CMS incorporates the full range of the New Visions core performance measures; for congestion, the core performance measure is excess delay.  Person hours are used for all values except for truck traffic, for which vehicle hours are considered more relevant.  The set of principles used in the CMS is shown in Table XX.


Table 3:  CDTC’s CMS Principles




Management of demand is preferable to accommodation of single-occupant demand growth.




Cost-effective operational actions are preferable to physical highway capacity expansion




Land use management is critical to the protection of transportation system investment.




Capital projects designed to provide significant physical highway capacity expansion are appropriate congestion management actions only under certain conditions.




Significant physical highway capacity additions carried out in the context of major infrastructure renewal are appropriate only under certain conditions (use of risk assessment here).




Incident management is essential to effective congestion management




Corridor protection and official street mapping are necessary to preserve options.


The CDTC process departs from the traditional approach to addressing travel needs.  CDTC strives first to maintain existing conditions and reduce the impact of forecasted travel by implementing demand management programs before considering capacity expansion; it uses the concept of risk assessment and tradeoff analysis in designing projects; and it is taking a fresh look at why travel occurs and why gridlock often does not.  


The level of traffic congestion today in the Capital District is generally acceptable, except on a few routes during peak hours.  However, CDTC forecasts a five-fold increase in unacceptable delay by the year 2015 as the result of projected development, a growth in both income and vehicle ownership, and shifts in the geographic distribution of activity toward suburban and exurban areas.  The number of critically congested corridors is expected to increase from 14 (1990) to 33 (2015) if nothing happens to mitigate the growth.  The Congestion Management System states that this “trend” will result in a congestion condition that is a threat to the Capital District.  The New Visions Transit Task Force noted that this increased highway congestion will also hurt transit, as the auto driver can take alternate routes while the bus rider is stuck in the traffic.


CDTC intends to revise its CMS principles and its identification of critical congestion corridors in the context of the New Visions 2030 exercise.  CDTC and NYSDOT will work together to try to develop procedures for the "tradeoff analysis" specified in CDTC's congestion management principles.  The tradeoff analysis is required in considering capacity aspects of highway projects, particularly infrastructure reconstruction projects.  CDTC also remains committed to examining the actual congestion relief benefits achieved from CMS projects.



Quantifying Congestion

In quantifying congestion, CDTC presently uses STEP, its travel forecasting model (CDTC is in the process of switching to VISUM).  CDTC maintains a current traffic count file containing all NYSDOT, CDTC and local machine and manual traffic counts.  Using NYSDOT’s extensive traffic data collection program on the State highway system, CDTC has been able to make a credible comparison of actual traffic growth relative to its STEP model forecasts.  The comparison shows that the overall forecasts have been quite accurate.  Because of the 1995 CMS was developed on these forecasts, CDTC’s year-2000 corridor priorities remain virtually unchanged.  The long development time for the major initiatives in the CMS has meant that the basic policy set of the 1995 CMS also remains unchanged.  For these reasons, the CDTC progressed minimal maintenance of the CMS to date.


The most significant aspect of CDTC’s approach to CMS since 1995 is that the concept has been, and continues to be, fleshed out.  CDTC is now rethinking the traditional approach to addressing forecasting and addressing travel, and base on past performance, this endeavor should prove interesting to the transportation community.


Identifying Congestion

Figure 13:  Congestion at Wolf Road & Albany Shaker Road, Town of Colonie

CDTC uses the concept of excess delay to identify areas of congestion.  Excess delay is the amount of time spent at a given location that exceeds the maximum amount of time that is generally considered acceptable.   Table XXX-2 shows the excess delay threshold values adopted by CDTC.  For auto and freight travel, excess delay is the amount of time spent at an intersection or along a highway segment in Level-of-Service (LOS) E and F conditions that exceed the maximum LOS D time.  Thus, if you sit in your automobile for more than 40 seconds waiting to go through an intersection, you are experiencing congestion at that particular location. 


Since the transportation user’s perception of congestion is related to its magnitude and/or severity, CDTC has identified those corridors that have significantly greater congestion than typical.  These corridors are defined as contiguous highway segments that, in aggregate, exceed certain thresholds.  By far, the most critically congested facility is the Adirondack Northway (I-87), having 1,263 excess person hours of delay, as compared with the second most sever highway having 437 excess person hours of delay.  The threshold values apply uniformly to auto, bus and freight transportation without additional monitoring efforts.



Investment Decisions

The congestion management principles in the CMS plan have had an increasing influence in regional transportation decision-making.  CMS, however, is considered in the context of everything else, rather than the driving force.  In choosing projects to be on the TIP, CDTC still does not entertain a stand-alone congestion project unless it is on the critical CMS list.  If an infrastructure project is up for discussion, it has a better chance of selection if it is also on the critical list.


The CMS plan established two main goals for use in making investment decisions:

·        support the growth in economic activity and quality of life by limiting the amount of excess delay; and

·        implement demand management programs first, before performing capacity expansions.


Table 4:  Excess Delay Threshold Values


             Facility Type


         Excess delay Threshold




40 seconds of stopped delay




1500 vehicles/lane, one direction/hour


Multi-lane Arterial w/median


1400 vehicles/lane, one direction/hour


Multi-lane Arterial w/o median


1250 vehicles/lane, one direction/hour


Two-lane Arterial and collector


1000 vehicles/direction/hour


Local (residential) road


625 vehicles/direction/hour

Thus, the CDTC strategy for reducing congestion is to employ a combination of TIP capital investments, incident management, demand management strategies, access management strategies, and operational measures.  CDTC's TIP has a multi-year commitment to develop and implement an Advanced Traffic Management System (ATMS) for the Capital District.   ITS is playing an increasingly important role in the Capital District, including such measures as the New York State Thruway Authority Electronic Toll Collection system (E-Z Pass) and the joint NYSDOT/State Police Transportation Management Center.


As discussed in Section VI: Transportation Improvement Program, candidate TIP projects go through a three-step process: screening, evaluation of merits, and project selection.  During the screening process, candidate projects must be determined to be consistent with the CMS component.  For projects specifically targeted at congestion mitigation, it must have local community support, be able to document that there does exist congestion (for highway capacity work), and the project must include commitments to local land use management (in the case of highway widening).  These criteria reinforce the regional planning process and assure that projects evaluated for funding meet the CMS’ seven principles.  The “Meeting an Identified Need” criteria for mobility projects is a Level of Service of E or below, either under current conditions or projected conditions in the year of programming, and must exist in order for the project to be evaluated further.


Once the project successfully passes through the screening process, it is assigned a detailed ranking based on the merits of the project.  Benefit to cost ratios (b/c) are calculated by CDTC staff wherever possible.  Five measures of project benefit are calculated:  safety, travel time, energy/user, life cycle and "other" benefits.   The cost benefits of proposed mobility improvements are measured by calculating savings in user operating cost and travel time savings[i] that would result from project implementation.   Future year traffic is assigned to the network with and without the proposed project.  User operating costs and travel time costs are calculated as the difference between the costs resulting from these two assignments.


In making investment decisions on capacity aspects of highway projects, particularly infrastructure reconstruction projects, CDTC has adopted a CMS-driven design approach, wherein any significant capacity additions carried out in the context of major infrastructure renewal are appropriate only under compelling conditions.  CDTC requires a tradeoff analysis inherent in the concept of Risk Assessment that focuses on the opportunity cost of selecting alternative designs.   The next section - Preservation of Existing Infrastructure - further details this approach.  



Managing Congestion on the System

While the trend line for vehicle travel demand shows a potential VMT increase of 30% by the year 2015, CDTC is committed to reducing the travel impact by one-third to one-half through travel demand management efforts and land use strategies.  Much of the reduction will be guided by the principles and proposed actions contained in the CMS.  Projects are designed for the traffic target, not for the trend (note: consultants have found it somewhat disconcerting to design for traffic less than projected). 


CDTC’s approach appears to be working well in practice, as the STEP Model forecasted an average annual growth rate for PM peak-hour VMT of 2.5% for the 1990's, compared to the actual VMT on the State touring routes of 1.9% during this period.  Thus, the preliminary indication is that VMT growth has on average been lower than forecast, hereby lending credibility to the New Visions assumption that traffic growth could be dampened with plan implementation.  CDTC hopes that the regional ITS deployment will help achieve the reduced VMT impact.  An update and refinement of the regional ITS program will be progressed for the New Visions 2030 effort. 



New Look at Accommodating Travel

The traditional approach to transportation investment in general, and highway congestion in particular, has been modified in the Capital District through its use of the concept of risk management (see Section VIII: Preservation of Existing Infrastructure).  CDTC, however, is embarked on a fundamental reassessment of the principles and reasons why people travel, challenging certain traditional assumptions.


For example, a traditional approach to congestion is to identify present or future locations of congestion and make improvements to achieve a certain Level of Service, the assumption being that an improved LOS would be the choice of the public.  However, the people of the Capital District have expressed their opinion that congestion should not be looked at as the sole measure of whether or not a highway improvement should be made.  During the survey of residents along the relatively congested Route 5 corridor, 79% said existing level of congestion along on Route 5 would be acceptable if other services were improved (transit, pedestrian, etc.).  In other words, maintaining the existing level of congestion was acceptable.


Oval: Investment in transportation is a choice – there is no “we have to do it.”Another topic being looked at by CDTC that challenges the traditional understanding of travel is:  Why doesn’t gridlock occur?  CDTC found that its overall forecast of future travel was fairly accurate, but its forecasts in certain congested corridors where congestion was expected to increase were not realized.  Mr. Poorman has speculated that personal and commercial travel behavior accounts for congestion through an equilibrium process that prevents gridlock.[ii]  We note that The Brookings Institute has recently voiced similar speculations.[iii]


Mr. Poorman notes that certain congested arterials in Albany (e.g., New Karner Road) have similar levels of congestion as they had 15 years ago, even with the addition of millions of square feet in new retail and commercial space in the area and few alternative routes to and from the new activity centers.


When new capacity is added to the highway system, people apparently tend to trade-in the travel timesaving benefit and move further out to the suburbs for bigger homes or possibly better schools.  Conversely, when an existing route becomes congested, people make alternative travel choices.  This apparent balancing effect leads to the idea that, in a region like the Capital District, investments are a choice – there is no “we have to do it”.  The choice is – where do we want the traffic and what physical condition do we want the system to be in?  CDTC staff will further explore these issues.

[i]  The average value of travel time of $8.18 per vehicle hour is presently used


[ii] Getting a Handle on the Impacts of Technological and Society changes on Travel in 2030, John Poorman 2000


[iii]  The Brookings Institution, Policy Brief #128, January 2004.