Connecticut Clean Air Construction Initiative

Air quality has a direct effect on human health and the environment. To help improve air quality in Greater New Haven, the Connecticut Department of Transportation (CTDOT) implemented methods for reducing emissions during the I-95 New Haven Harbor Crossing Corridor Improvement (I-95 New Haven) Program.


During construction on the I-95 New Haven Program, equipment used on highway contracts was part of a pilot emissions reduction program for the State of Connecticut. Several factors made the area and timing ideal for this initiative:

  • Construction took place along a densely-populated corridor. Reduced chemical and particulate emissions benefit area residents and visitors, as well as laborers working near diesel engines.
  • Construction spanned approximately 18 years. The emissions-reduction initiative reduced the impact on air quality that would otherwise be associated with such a large-scale, long-term construction project.
  • One of the nation's first emissions reduction programs was operated successfully on Boston's "Big Dig." CTDOT was encouraged by Boston’s results and eager to implement a similar program in Connecticut.


The CTDOT required all contractors and sub-contractors to take part in the Connecticut Clean Air Construction Initiative.

In summary, the following contractor requirements applied:

  • Emission control devices (such as oxidation catalysts) and/or clean fuels were required for: 
    - Diesel-powered construction equipment, with 
    - Engine horsepower (HP) ratings of 60 HP and above, that are 
    - On the project or assigned to the contract in excess of 30 days.
  • Truck staging zones were established for diesel-powered vehicles waiting to load or unload materials. The zones were located where diesel emissions will have the least impact on abutters and the general public.
  • Idling was limited to three minutes for delivery and dump trucks and other diesel-powered equipment (with some exceptions).
  • All work was conducted to ensure that no harmful effects are caused to adjacent sensitive receptors, such as schools, hospitals, and elderly housing.
  • Diesel-powered engines were located away from fresh air intakes, air conditioners, and windows.

Initial and monthly reporting by contractors ensured the proper implementation of the Connecticut Clean Air Construction Initiative. Non-compliance was enforced with a 24-hour notice to the contractor to improve a vehicle or remove it from a project.

To introduce this new program to area contractors, three informational meetings regarding clean fuels and equipment retrofitting were conducted in August and September 2001. The sessions were attended by clean fuel vendors and equipment manufacturers who addressed concerns about equipment maintenance and warranties.


The cost of retrofitting equipment or using clean fuels was included in the general cost of the contract, as bid by each contractor. Whereas a contractor who owned equipment may be more likely to install the retrofit apparatus, one who rented equipment may have opt to use clean fuels.

Equipment Maintenance and Warranties

On I-95 New Haven Program projects, no adverse operational problems or additional maintenance costs were reported for construction equipment retrofitted with oxidation catalysts. With proper installation, and as long as a system was not stressed beyond its design limitations, equipment warranties were not affected by installation of retrofit products.

Looking Forward

With good maintenance, heavy machinery with diesel engines can operate for more than 20 years. Retrofitting an engine cuts the lifetime emissions from that engine to a small percentage of what it is today. The EPA, CTDOT, and other local agencies support these measures in their dedication to improving the air quality in the State of Connecticut.

For more information on construction air quality, please refer to the following links and papers: