PORTLAND — Traffic on Washington Avenue between Veranda and Presumpscot streets will be delayed today as the contractor for Unitil’s gas system upgrade project begins installing a new gas main.

The construction work will take place between 7 a.m. and 7 p.m. and is expected to continue throughout the month of June.

Only one lane of traffic in each direction will remain open during that time. On-street parking will also be affected by the project.