@
Vanasse Hangen Brusilin, Inc.
» Traffic signal controller cabinet modifications to provide southbound Spring
Street traffic signal phasing (proposed to be split from Medical Center Drive’s
green indications given the moderately high volume of conflicting Spring Street
left-turn to Medical Center Drive through and right-turn movements).
Traffic operational analysis shows levels of service to remain the same (LOS B) as the
No Build condition for the AM and PM peak hours at the All-Way STOP intersection
of Spring Street and East Pearl Street. This result is based upon a forecast diversion
ranging from 50-75 vehicles to southbound Spring Street during peak hours. Table 8
summarizes the traffic operational results compared to the existing condition at the
signalized intersection of Spring Street and East Hollis Street.
Table 8 - Signalized Intersection Capacity Analysis Summary
East Hollis St. at Spring St.
No Action 2-Way Spring St.
1-Way Spring St. Alternative
(Exclusive PEDs) (Exclusive PEDs)
vic* Delay** LOS** v/c Delay LOS
AM 0.42 3] C 0.53 40 D
PM 0.59 44 D 0.68 60 E
2-Way Spring St.
Alternative
(Concurrent PEDs)
vic Delay LOS
0.49 31 Cc
0.63 37 D
* Volume to Capacity Ratio.
** Delay in seconds per vehicle,
“ Level of Service.
\whblpeofiBediorS2700.00 Nashua
Chrtulallon Studreports Final Report Final
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The results of the signalized operational analysis shows a drop in LOS (from D to E)
during the critical PM peak hour with the Spring Street southbound approach added
to the existing signalized intersection and retention of the exclusive pedestrian
phasing. In addition to the drop in LOS, eastbound vehicle queues along East Hollis
Street are forecast to reach Main Street. The forecast drop in LOS and increased
vehicle queuing are undesirable changes to operating conditions that may require
mitigation.
One potential modification to improve LOS and reduce vehicle queuing at the
signalized intersection is a change from exclusive pedestrian signal phasing (where
all traffic stops for any pedestrian pushbutton actuation) to concurrent pedestrian
signal phasing (where the WALK signal is displayed and pedestrians cross with
moving vehicle traffic adjacent to the crosswalk, noting turn vehicles are instructed
by way of regulatory signage as well as state statutes to YIELD to any pedestrian ina
crosswalk). Discussion on the advantages and disadvantages of exclusive versus
concurrent pedestrian phasing can be found in earlier sections of this report. As
shown in Table 8, operational level of service is forecast to remain the same as the
Alternatives Evaluation
