HAVERHILL — If you've traveled Interstates 93 or 495 in the Merrimack Valley recently, you may have noticed that exit numbers are not what they used to be.
The state is engaged in making a change from the decades-old sequential exit numbering system to a milepost-based numbering system, complying with a federal requirement, according to officials with the Massachusetts Department of Transportation.
The statewide project that began last fall involves covering the existing numbers with overlays bearing the new numbers.
It may seem a bit confusing at first, but state transportation officials say the new exit signage will include “Old Exit” signs in key locations for a minimum of two years, to help drivers get acquainted with the new system.
Locally, the change to a milepost-based numbering system affects Interstates 93, 495 and 95. The work is expected to be completed by the end of this week.
Examples of the changes for I-495 include Exit 48 for the Ward Hill Connector in Haverhill, which is now Exit 106.
For I-93, examples include Exit 47 at Pelham Street in Methuen is now Exit 45.
Exit numbers for Route 213 in Methuen will not be changing, officials said.
A downloadable map highlighting old and new exit numbers is available on the project website at newmassexits.com.
MassDOT officials said the benefits of the change include making it easier for drivers to quickly determine distances to their destinations and more easily calculate miles traveled; improve reporting of highway incidents resulting in better navigation of emergency services; allow for the addition of future exits without having to renumber an entire corridor of travel, and create uniformity with the exit numbering scheme being used by most other states.
According to MassDOT, per the 2009 Federal Highway Administration Manual on Uniform Traffic Control Devices, MassDOT is required to convert all exit numbers on freeways to a milepost-based numbering system.
Massachusetts was one of three states not in compliance with the requirement, officials said.
If MassDOT chose not to comply with the Federal mandate to change the exit numbers to milepost-based, it risked losing federal funding for future highway construction and safety programs, officials said.
Only 10% of the cost of the project will be paid for with state highway money, MassDOT officials said.