Road Safety AuditBlair Road/Cedar Road/4th Street Intersection

DDOT Transportation Safety Team

BackgroundPurpose & Need Formal safety performance examination of roadway or

intersection by an independent, multidisciplinary road safety audit (RSA) team

It qualitatively estimates and reports on potential road safety issues and identifies opportunities for improvements in safety for all road users

Blair Rd/Cedar St/4th St intersection identified by District as a safety problem location

RSA team would identify safety issues at this location and suggest countermeasures for improvements in safety

Road Safety Audity (RSA) Team DDOT - Safety, Signals, IPMA, PPSA, PTSA, Bike & Peds, Parking, Street lighting, NHTSA and UFA USDOT - FHWA MPD WMATA FEMA

RSA Team

Road Safety Audit Procedure

We are here

Accident Analysis

3-year accident analysis

Total 24 accidents from 2008-2010 11 out of 24 accidents (50%) resulted in injuries

4 out of 24 accidents (20%) resulted in disabling injuries

Blair/Cedar – 15 accidents (60%)4th/Cedar – 7 accidents (30%)Blair/4th – 2 accidents (10%)

2008 2009 20100

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98 8 8

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AccidentsTotal InjuriesDisabling InjuriesCr

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2008 2009 20100

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98 8 8

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Observations

Following issues affect traffic and pedestrian safety at intersection

1. Complex intersection geometry and traffic control;2. Significant pedestrian-vehicle conflicts;3. High accident frequency;4. Insufficient traffic signage;5. Faded pavement markings

Traffic Analysis – Existing Conditions Estimated 2010 Average Daily Traffic Volumes

i. Blair Rd – 15000 vehiclesii. Cedar St – 5300 vehiclesiii. 4th St – 1600 vehicles

Speed study shows 32 mph speed on Blair Rd which is significantly higher than posted 25 mph speed limit

Existing level of service (LOS) analysis at 21 intersections along Blair Rd, Piney Branch Rd, Aspen St, Butternut St and Cedar St

Blair Rd/4th St/Cedar St intersection operates at:i. LOS E during AM peak-hourii. LOS F during PM peak-hour

Traffic Analysis – Existing Conditions Blair Rd intersection at Piney Branch Rd operates at LOS E during AM peak-hour

Remaining study intersections operate at LOS D or better during both AM and PM peak-hour

Proposed Alternatives

Alternative #1 Alternative #2 Alternative #3

Only roadway geometric improvements

Both roadway geometric & traffic signal improvements

Only roadway geometric improvements

4th St – One Way, SBBlair Rd to Butternut St

4th St – One Way, SBBlair Rd to Butternut St

Permanently close 4th StBlair Rd to Butternut St

Butternut St – One Way, EB 4th St to Blair Rd

Relocate crosswalks on Cedar St and Blair Rd

Blair Rd – One Way, NBCedar St to Butternut St

Blair Rd – One Way, NBCedar St to Butternut St

Split phase on Blair Rd + overlap for WB right-turns (WBRT)

Blair Rd – One Way, SB Dahlia Rd to Cedar St

Blair Rd – One Way, SB Dahlia Rd to Cedar St

No EB & NB left-turns; Leading left for WB left-turns

Cedar St – One Way, WB5th St to 4th St

Eliminate Right-Turn Lane WB Approach of Cedar St

No Turn on Red for WBRT on Cedar; WBRT only on Overlap

Eliminate Right-Turn Lane onWB Approach of Cedar St

Signal Phasing Improvements in Alternative #2

Split phasing on Blair Rd with overlap for WB right-turns

At the beginning of cycle:i. SB vehicles receive ROW at beginning of cycleii. WB right-turns simultaneously maneuver on overlap phase.iii. West X-walk concurrently receives walk interval

NB vehicles receive ROW after termination of SB phasei. NB left-turns are NOT allowedii. East X-walk concurrently receives walk intervaliii. West X-walk continues to receive walk interval

WB left-turns and thru traffic receive ROW after termination of NB phasei. “No Turn on Red” prohibition for WB right-turnsii. North X-walk on Blair Rd concurrently receives walk interval

Signal Phasing Improvements in Alternative #2

Split phasing on Blair Rd with overlap for WB right-turns

EB traffic receives ROW after termination of leading left-turn phase on WBi. EB left-turns not allowed ii. “No Turn on Red” prohibition for WB right-turnsiii. EB right-turns and WB left-turns maneuver on permissive phasingiv. South X-walk concurrently receives walk intervalv. North X-walk continues to receive walk interval

Signal Phasing Improvements in Alternative #2

Primary Advantages

No conflicts for pedestrians in North X-walki. WB right-turns only allowed on overlap phaseii. “No Turn on Red” prohibition for WB right-turnsiii. EB left-turns not allowed

Eliminates SB left-turn conflicts with pedestrians in East X-walki. Exclusive ROW for NB and SB vehicles on Blair Rdii. Concurrent walk interval with NB traffic only

Traffic Analysis – Future Conditions Roadway improvement under first and third alternatives cause:

i. Significant diversion of existing travel patternsii. Significant increase in traffic volumes on Aspen St, Butternut St & Cedar Stiii. Considerable traffic calming and pedestrian safety issues in residential

neighborhoodsiv. Do not propose signal phasing improvements to reduce pedestrian

accidents

Roadway and signal phasing improvements under second alternative:i. Do not cause significant diversion of existing travel patternsii. Improve intersection level of serviceiii. Enhance sight distance and pedestrian visibilityiv. Eliminate critical pedestrian-vehicle conflicts

Therefore, RSA team recommends Second Alternative

Conceptual Design for Alternative #2

Safety Issue #1 - Complex Intersection Geometry and Traffic ControlSkewed Intersection Geometry

5 leg intersection has skewed geometry 4th St intersects Blair Rd at sharp angle 4th St and Blair Rd have minor offsets south of the intersection 4th St serves as an outlet for cut-through traffic that wants to circumvent queuing on Blair Rd

Vehicles on 4th/Blair travel in “snake pattern” due to the minor offsets Horizontal & vertical alignments don’t provide easy access for bikes and pedestrians

No pedestrian signal for X-walk on 4th St Upgrade all pedestrian facilities to meet new ADA specifications Multiple curb cuts impact traffic movements and pedestrian access

Safety Issue #1 - Complex Intersection Geometry and Traffic ControlComplex Traffic Control

SB left-turns (SBLT) on Blair Rd block intersection and also run red light Direct conflict with opposing vehicles on 4th St and Cedar St Conflict with pedestrians in X-walks on both Blair Rd and Cedar St Above photo shows 4 SB left-turns on Blair Rd blocking intersection and jumping red light

SB thru vehicles cut across west X-walk on Cedar St to circumvent SBLT that block the intersection Direct conflict with the pedestrians on west crosswalk on Cedar St

Multiple traffic signals for 4th St and Blair Rd Motorists confused in deciding - when to leave the intersection; and - who has pertinent right-of-way

Safety Issue #1 - Complex Intersection Geometry and Traffic ControlInadequate Sight Distance

WB right-turns on Cedar St cannot see pedestrians in North X-walk on Blair Rd

Vehicles on 4th St cannot see pedestrians in X-walks on Cedar St

Vehicles on NB Blair Road cannot see pedestrians in X-walks on Cedar St

Vehicles on SB Blair Road cannot see pedestrians in east X-walks on Cedar St

Safety Issue #1 - Complex Intersection Geometry and Traffic ControlInadequate Sight Distance

Solutions for Safety Issue #1 Relocation of east X-walk on Cedar St and south X-walk on Blair Rd would significantly

improve visibility of pedestrians in: i. East X-walk on Cedar St for SB left-turns on Blair Rdii. North X-walk on Blair Rd for WB right-turns on Cedar Stiii. East and west X-walks on Cedar for NB vehicles on Blair Rd

Split phasing with right-turn overlap operations would: i. Eliminate SB left-turn conflicts with pedestrians on east X-walkii. Eliminate WB right-turn conflicts with pedestrians on north X-walkiii. Stop SB thru vehicles from cutting-across west X-walkiv. Restrict red light running of SB left-turnsv. Restrict SB vehicles from blocking the intersectionvi. Significantly lessen the number of accidents

Proposed roadway geometric improvements would:i. Eliminate the skewed intersection geometry;ii. Significantly improve pedestrian visibilityiii. Eliminate cut-through traffic on 4th St

Solutions for Safety Issue #1 Proposed traffic signal phasing improvements would:

i. Significantly improve the intersection level-of-service;ii. Eliminate critical SB left-turn and WB right-turn conflicts with pedestrians

Revise traffic signal design to:i. Properly align vehicle signal heads with travel laneii. Install pedestrian signals on all X-walksiii. Provide adequate intersection sight distanceiv. Eliminate multiple traffic signals for south leg of Blair Rdv. Pedestrian facilities meet new ADA specifications

Safety Issue #2 – Significant Pedestrian-Vehicle ConflictsNorth Crosswalk on Blair Rd

North X-walk on Blair Road is located far behind the intersection Inadequate sight distance for westbound right-turns (WBRT) to observe pedestrians in north X-walk Green interval for WBRT coincides with Walk interval causing direct pedestrian-vehicle conflicts

Businesses located at corner of intersection also obstruct the sight triangles WBRT can only observe pedestrians at the corner of intersection Confusing “Pedestrian Use X-walk” sign at corner of intersection should be removed

Blair Rd X-walk not visible from WB Cedar St Confusing “Pedestrian Use X-walk sign

Safety Issue #2 – Significant Pedestrian-Vehicle ConflictsCrosswalks on Blair Rd and Cedar St

Sight obstructions plus concurrent walk intervals cause pedestrian-vehicle conflicts on Blair Rd Median opening allows jaywalking and illegal U-turn vehicle maneuvers

On-street parking of delivery trucks on WB Cedar St and NB Blair Rd significantly obstructs pedestrian visibility

Cedar St X-walk not visible from SB Blair Rd

SB thru vehicles cut across west X-walk on Cedar St

SUV making illegal U-turn at opening in raised median

Solutions for Safety Issue #2

Relocation of east X-walk on Cedar St and south X-walk on Blair Rd would significantly improve visibility of pedestrians in:

i. East X-walk on Cedar St for SB left-turns on Blair Rdii. North X-walk on Blair Rd for WB right-turns on Cedar Stiii. East and west X-walks on Cedar for NB vehicles on Blair Rd

Split phasing with right-turn overlap operations would: i. Eliminate SB left-turn conflicts with pedestrians on east X-walkii. Eliminate WB right-turn conflicts with pedestrians on north X-walkiii. Stop SB thru vehicles from cutting-across west X-walkiv. Restrict red light running of SB left-turnsv. Restrict SB vehicles from blocking the intersectionvi. Significantly lessen the number of accidents

Close median opening and install pedestrian channelizing fence on WB Cedar St Prohibit on-street parking for delivery trucks along Blair Rd and Cedar St

Safety Issue #3 – High Accident FrequencyBlair Rd and Cedar St Approach

15 accidents with one pedestrian crash SBLT frequently run red light at this location Conflict with vehicles from Cedar St causing right angle and sideswipe accidents Conflict with peds in X-walks on Cedar and Blair due to red light running & limited sight distance

SB thru vehicles cut across west X-walk causing direct pedestrian conflicts Potential for rear-end accidents with SBLT on Blair Road Limited sight distance because of skewed geometry on Blair Rd

Safety Issue #3 – High Accident Frequency4th St and Cedar St Approach

7 accidents with two pedestrian crashes on this approach SB left-turns frequently block intersection and run red lights at this location Conflict with vehicles from 4th St causing right angle and sideswipe accidents 4th St motorists can’t observe pedestrians on Cedar St due to sight obstructions

SB left-turns (SBLT) blocking the intersection Limited Sight Distance & Confusing Signals on 4th/Blair

Safety Issue #3 – High Accident Frequency4th St and Blair Rd Approach

2 right-angle accidents on this approach Multiple traffic signals confuse motorists on Blair Rd and 4th St in deciding: (i) When to leave the intersection and; (ii) Who has pertinent right-of-way (ROW)

Potential rear-end accident at 4th/Blair Potential right-angle accident at 4th/Blair

Green interval gives false indication of ROW causing right-angle and rear end accidents Inadequate sight distance on 4th St and Blair Rd causes pedestrian-vehicle conflicts

Solutions for Safety Issue #3

Blair Rd and Cedar St Approach

Relocation of east X-walk on Cedar St and south X-walk on Blair Rd would significantly improve visibility of pedestrians in:

i. East X-walk on Cedar St for SB left-turns on Blair Rdii. North X-walk on Blair Rd for WB right-turns on Cedar Stiii. East and west X-walks on Cedar for NB vehicles on Blair Rd

Split phasing with right-turn overlap operations would: i. Eliminate SB left-turn conflicts with pedestrians on east X-walkii. Eliminate WB right-turn conflicts with pedestrians on north X-walkiii. Stop SB thru vehicles from cutting-across west X-walkiv. Restrict red light running of SB left-turnsv. Restrict SB vehicles from blocking the intersectionvi. Significantly lessen the number of accidents

Install red light cameras on WB approach of Cedar St and SB approach of Blair Rd Enforce speed limits by installing speed cameras

Solutions for Safety Issue #3

4th St and Blair Rd Approach

Relocation of south X-walk on Blair Rd would significantly improve visibility of pedestrians for NB vehicles on Blair Rd

Split phasing on Blair Rd in conjunction to “One-way SB Only” maneuver on 4th St would: i. Stop SB thru vehicles from cutting-across west X-walkii. Restrict red light running of SB left-turnsiii. Restrict SB vehicles from blocking the intersectioniv. Significantly lessen the number of accidents

Revise signal design to eliminate multiple traffic signals

Install red light cameras on SB approach of Blair Rd

Enforce speed limits by installing speed cameras

Solutions for Safety Issue #3

4th St and Cedar St Approach

“One-Way SB Only” maneuver on 4th St would significantly reduce vehicular accidents

Relocation of south X-walk of Blair Rd would significantly improve pedestrian visibility for vehicles on Cedar St

Enforce speed limits by installing speed cameras

Safety Issue #4 – Insufficient Traffic SignageConfusing Traffic Signs

No pedestrian crossing signs on all approaches at this location No advance warning sign for Blair Rd X-walk on WB approach of Cedar St Confusing “Right-Lane” and “Pedestrian Use X-Walk” sign on WB Cedar St should be replaced by appropriate MUTCD traffic signs

Safety Issue #4 – Insufficient Traffic SignageImproperly Placed Traffic Signs

“No Turn On Red” sign is improperly placed on all approaches Vegetation restricts visibility of traffic signs on EB approach of Cedar St Damaged sign post on EB approach of Cedar St Clutter of traffic signage on Blair Rd and Cedar St

Solutions for Safety Issue #4

Pedestrian crossing signage on all approaches

Advance warning signs for Blair Rd X-walk on WB approach of Cedar St

Replace “Right-Lane” sign with “Stop Here for Pedestrians” (R1-5c, 2009 MUTCD) sign

Replace “Pedestrian Use X-walk” sign with revised “Side of Street Pedestrian” (R1-6a(1)) sign

Proper placement of “No Turn on Red Sign” on all approaches

Replace damaged signpost on EB Cedar St

Reorganize traffic signage to eliminate sign clutter

Adequate street lighting in revised signal design

Safety Issue #5 – Faded Pavement MarkingsPotholes & Cracks

Pavement markings are worn or missing adding to motorist confusion Pedestrian X-walks are in conflict with storm drain facilities Numerous cracks and potholes in pavements causing safety hazards Pedestrian facilities are not compliant per the new ADA specifications

Solutions for Safety Issue #5

Restripe and maintain durable pavement markings at the study intersection

Pedestrian facilities are designed to the new ADA specifications in the revised traffic signal design