City of Somerville Davis Square Signal Timing Changes May 2018
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current timing 130 ‐ second signal cycle in AM/PM peak • Longer than 90 ‐ second “ideal maximum” (NACTO) and 120 ‐ second “target maximum” (HCM) – Long cycle lengths lead to delay for all users – May create safety issues as users more likely to run red lights in congested conditions (V/C >0.65) – 155 ‐ second cycle on Saturday • More delay for buses and pedestrians – Same signal timing in AM and PM • Not adaptive to fluctuations in traffic over the course of a day – Highland Ave thru traffic experiences an average of 168s of delay in AM peak, 44s in PM peak – Pedestrian phasing • Exclusive pedestrian phases show lower compliance than concurrent phases – Longer pedestrian delays = lower compliance – 26s 26s 34s 5s 14s 25s =130s cycle
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing ‐ Overview Blue arrows represent • vehicle flows (who has the green light)
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing ‐ Overview Blue arrows represent • vehicle flows (who has the green light) Green circles represent • common, but illegal pedestrian crossings during each phase
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing ‐ Overview Current phasing Blue arrows represent • vehicle flows (who has the green light) Green circles represent • common, but illegal pedestrian crossings during each phase Green arrows represent • legal pedestrian crossings (pedestrian signal is on)
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing ‐ Overview Current phasing Blue arrows represent • vehicle flows (who has the green light) Green circles represent • common, but illegal pedestrian crossings during each phase Green arrows represent • legal pedestrian crossings (pedestrian signal is on) Not discussed: • Unsignalized crosswalks
City of Somerville – Davis Square Signal Timing Planning Discussion April 2018 Current phasing
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – Highland Ave phase 26 Seconds • Crosswalks across College • used when right ‐ turns from Highland cease Crosswalk across Elm used • during Day Street phase
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – Holland St Phase 26 Seconds • Crosswalk across Day has • no conflicts Crosswalks across College • used when right ‐ turns from Highland stop Crosswalk across Dover • used when there’s a gap in traffic Leapfrogging to divider • island is common
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – College Ave phase 34 Seconds • Crosswalk across Holland • used during this phase, as College right ‐ turn volume is low (28 AM, 35 PM, 27 Saturday) Crosswalk across Day has • no conflicts Peds cross Highland if no • cars are in the right ‐ turn lane Leapfrogging to divider • island is common
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – College Clearance 5 seconds • Phase used to clear out • area in front of busway No conflicts to cross • Highland No conflicts to cross • College at MBTA station
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – MBTA Busway Phase 14 Seconds • MBTA bus phase, but • relatively few buses In AM, 9 left turns and 9 – right turns In PM, 5 left turns and 8 right – turns On Saturday midday, 6 left – turns and 7 right turns All crosswalks appear • relatively safe to use Crosswalks across Day, • Dover, and Highland are 100% safe to use
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – Pedestrian Phase 25 Seconds • Exclusive pedestrian • phase; all pedestrian signals on, all traffic stopped Long enough to cross one • leg of intersection, but no more (few exceptions)
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing ‐ Issues 25 Seconds • Exclusive pedestrian • phase; all pedestrian signals on, all traffic stopped Long enough to cross one • leg of intersection, but no more (few exceptions) Example: Takes between • 3.5 and 6.5 minutes (3 walk cycles) to legally walk between JP Licks and Oath
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing ‐ Issues 25 Seconds • Exclusive pedestrian • phase; all pedestrian signals on, all traffic stopped Long enough to cross one • leg of intersection, but no more (few exceptions) Pedestrians “scramble” • outside of crosswalks May result in pedestrians in – the intersection after the phase ends Not possible for all users –
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Bottom line Existing phasing is: • Encouraging potentially – dangerous pedestrian movements Extremely time ‐ consuming – for pedestrians Or both – The “Don’t Walk” signal • sends mixed messages Mandate or suggestion? – Knowledge of the • intersection is key if you want to navigate the Square in a timely manner Davis Square intersection • can act as a barrier
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Proposed phasing 100 ‐ second signal cycle • 30 ‐ 55 seconds shorter than existing – Reduced delay for all users – Concurrent and “protected” pedestrian phases • Pedestrians legally allowed to cross during parallel vehicle traffic – Where there are turning conflicts, pedestrians given 7 ‐ second “head start” (Leading Pedestrian – Interval) Peds always allowed to cross when there is no conflict present – Exclusive pedestrian phase removed • Reduces cycle length – 7s LPI + 7s LPI + 24s 5s 14s 25s 18s =100s cycle
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – Highland Ave LPI 7 Seconds •
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – Highland Ave phase 25 Seconds • Right ‐ turning vehicles from • Highland Avenue must yield to pedestrians Day Street vehicles must • yield to peds crossing Elm
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – Holland St Phase 24 Seconds • Crosswalk across Day • Street has no conflicts Highland Avenue right ‐ • turners must yield to peds Highland Avenue left ‐ • turners and Holland Street right ‐ turners must yield to peds
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – College Ave LPI 7 seconds •
City of Somerville – Davis Square Signal Timing Planning Discussion April 2018 Current phasing – College Ave phase 18 seconds • Small number of right ‐ • turns must yield to peds crossing Holland Street No conflicts for peds • crossing Day Street
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – College Clearance 5 seconds • Phase used to clear out • area in front of busway No conflicts to cross • Highland Avenue No conflicts to cross • College at MBTA station
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Current phasing – MBTA Busway Phase 14 Seconds • Only conflicts are with • buses, which are relatively few and slow ‐ moving
City of Somerville – Davis Square Signal Timing Planning Discussion May 2018 Benefits Reduced cycle length = less delay for all users • Improved vehicle operations • Average improvement of 35 seconds in AM peak – Average improvement of 8 seconds in PM peak – MBTA busway delay reduced by 15 seconds – Pedestrian delay significantly reduced • Existing maximum delay was 105 for all crossings – Future pedestrian delay improves by 24 and 99 seconds depending on crosswalk location/time of day – Over the course of an hour: Each crosswalk would get a “Walk” signal 8 more times • Highland Avenue would get about 3 more minutes of green time • Holland Street would get about 2.5 more minutes of green time • MBTA busway would get 8 more green signals •
Recommend
More recommend
