With regards to using a diagrammatic sign despite no available option lane; such is allowed (i.e. grandfathered) if supporting and/or predecessor interchange signage contained similar. The original 1988-era signage featured such as well.
MUTCD § 2E.20 bans the use of either type of diagrammatic (OAPL or stippled-arrow), without qualification, when option lanes are not present:
Overhead Arrow-per-Lane or Diagrammatic guide signs shall not be used on freeways and expressways for any other types of exits or splits, including single-lane exits and splits that do not have an option lane.
At locations that do have option lanes, stippled-arrow diagrammatics are grandfathered in because § 2E.21 requires OAPL only on new or reconstructed freeways:
Overhead Arrow-per-Lane guide signs shall be used on all new or reconstructed freeways and expressways as described in Section 2E.20.
With all due respect, and Roadman can confirm/clarify, MassDOT/Mass Highway has used diagrammatic signs in split situations without option lanes
prior to the 2009 Edition of the MUTCD being published.
Even MUTCD somewhat acknowledges that such was used in the past (
bold & underline emphasis added):
Design of Freeway and Expressway Diagrammatic Guide Signs for Option Lanes
Support:
01 Diagrammatic guide signs (see Figure 2E-7) are guide signs that show a simplified graphic view of the exit
arrangement in relationship to the main highway. While the use of such guide signs might be helpful for the
purpose of conveying relative direction of each movement, Diagrammatic guide signs have been shown to be less
effective than conventional or Overhead Arrow-per-Lane guide signs at conveying the destination or direction(s)
that each approach lane serves, regardless of whether dedicated or option lanes are present.
Such indirectly
admits that the practice of using diagrammatic signs for interchanges without option lanes have been done in the past.
That said, such wouldn't be the first time a state DOT agency told MUTCD to pound sand on certain criteria items.
As previously stated, other diagrammatic signs with no option lane for the I-95/MA 128 interchange
do presently exist in the field.
3/4 - mile advance diagrammatic sign1/3 - mile advance diagrammatic signThe signs at the I-95/MA 128 Split for the actual lane configuration.
The proposed 2-mile sign is just matching its mates in kind, MUTCD standard or no MUTCD standard.
As previously mentioned and regardless of the above-MUTCD's commentary on its limited effectiveness, the current & previous-original 1988-vintage diagrammatic signs for this interchange
do indeed work. I've passed through this interchange ever since it was first built in the late 80s.
Apparently, MassDOT agrees since brand new diagrammatic signage w/no option lane for the westbound I-90/84 split in Sturbridge has since been recently erected.
1 - mile advance sign for I-90/84I asked Roadman regarding such and he stated that MassDOT thought the diagrammatic design would better assist motorists despite having no option lane. Having used this interchange many times for 30+ years; I have seen several times, vehicles
criss-crossing at the last moment. Time will tell whether or not the new advance diagrammatic signs will reduce the number of last-second criss-crosses and related-accidents.