I-26 Safety Project

Project CorridorI-26 between I-95 and Summerville• Number one and three ranked location for interstate safety

improvements• AADT = 32,433 • Posted S/L = 70 mph• Crash Stats: January 2007 through November 2011• Total Crashes = 1934• Total Fatalities = 44• Total Injuries = 709• 50% Run off Road Crashes

• Post and Courier coined the phrase “Corridor of Death” in 2010 articles

Project Corridor

Project Corridor Safety Data

• Existing Median Width = 84’ – 86’ • Existing Median Shoulder = 2’ - 3’ (paved)• Distance from travel way to tree line = 25’• Clear Zone Distance = 46’

Median Rt. Side Median Rt. Side0

1020304050607080

Incapaciting InjuriesFatalitiesCrashes

Berkeley Dorchester

Project Corridor Safety Data

Distracted / Asleep **

DUI Speeding Too Fast for conditions

(wet roadway) **

Tire failure ** Improper lane change **

Debris in roadway **

0

2

4

6

8

10

12

14

16

18

Berkeley

Dorchester

** Vehicular speeds were estimated by investigating officer to be within posted speed limits.

Project Corridor Safety Data

0

5

10

15

20

25

30

35

40

45

50

8

16

9

01

4 42 3

5

2 13 2 3 3

43 4 3

52 2

0

35 6

5

8

3 46 6

24

8

57

4 3

6

9

6

141416

8

25

12

23

11

7 8

17

13

28

16

25

12

42

11

20

1211

1615

8

11

14

37

21

14

2221

3

13

46

33

18

29

15

I-26 Tree Crashes Per Mile

State Average

0

I-77

US

601

I-95

FOU

R H

OLE

SW

AMP

US

17 A

LT

US

21

US

301

CYPR

ESS SW

AMP

I-26 Safety AlternativesRemove obstacles

Provide clear zone• clearing of median • Median consists primarily of

pines with light mixture of hardwoods

• environmental permit required• Standard cable rail to be installed

in center of median• Initial cost estimate of $5M• Would prepare median for future

widening

I-26 Safety Alternatives

• Cable would be required for both directions of I-26

• Initial cost estimate of $10M• Considerable maintenance, repair

and traffic impact concerns

Shield Obstacles

• High tension cable rail only feasible option due to close distance of trees and existing shoulder slopes

Project DetailsExisting Conditions

• Total Length of project corridor – 29.6 Miles• Total Length of Existing Guardrail along median– 2.2 Miles• Median Length with no existing trees – 2.6 Miles

• Median Length with existing median cable rail – 0.9 Miles• Median width occupied by trees – 36 feet maximum• Wetlands within Project Limits – 4.2 Acres• Overlap with Existing Projects

• Sheep Island Interchange• I-26 Widening (Jedburg Road)

Preferred Alternative DetailsAlternative Feature

• Exclude median areas protected by existing guardrail

• Extension of existing steel beam guardrail in areas of steeper slopes• 1.8 Miles of new steel beam

guardrail • Reduce tree impacts to only the

trees necessary to allow for the installation of the guardrail

• Wetland impacts reduced from 4.2 to 1.9 acres• SCDOT has received authorization

from the Army Corps of Engineers based on these conditions

Preferred Alternative DetailsAlternative Considerations

• No glare shield provided• Median width greater than 20

feet• Can accommodate emergency

crossovers and will bring up to standards with coordination with the local emergency agencies

Preferred Alternative DetailsAlternative Elements

• 23.0 miles of clearing, grubbing, dressing and grassing of the median ( 6 miles overlaps with the I-26 widening and Sheep Island Parkway Interchange)• 24.7 miles of median cable

rail• 1.8 miles of new steel beam

guardrail

I-26 Safety Project