Trinity Highway MPS 350X - Controlling Skid Distance (Roll Ahead)

www.trinityhighway.com 10 Revision C December 2017
Controlling Skid Distance (Roll Ahead)
The use of a TMA on the back of a truck will not:
 Affect the skid (roll ahead) distance of an impacted truck. KEEP WORK CREWS CLEAR!
Controlling skid distance (roll ahead):
 Skid distance is significantly increased and is less predictable for lightweight shadow
vehicles.
 Skid distance is reduced and is more consistent when heavier shadow vehicles are used.

Required minimum truck weight: 6,804 kg. [15,000 lbs.] or greater.
Roll-Ahead Distance for Shadow Vehicles
Weight of Shadow
Vehicle (Moving)
Prevailing
Speed km/h
[mph]
Weight of Impacting Vehicle to be Contained*
2,040 kg
[4,500 lbs]
4,536 kg
[10,000 lbs]
6,804 kg
[15,000 lbs]
10,886 kg
[24,000 lbs]
6,804 kg [15,000 lb]
96-105 [60-65] 23 m [75 ft] 46 m [150 ft] 53 m [175 ft] 69 m [225 ft]
80-88 [50-55] 23 m [75 ft] 38 m [125 ft] 46 m [150 ft] 53 m [175 ft]
72 [45] 15 m [50 ft] 30 m [100 ft] 30 m [100 ft] 30 m [100 ft]
10,886 kg [24,000 lb]
96-105 [60-65] 23 m [75 ft] 30 m [100 ft] 46 m [150 ft] 53 m [175 ft]
80-88 [50-55] 15 m [50 ft] 23 m [75 ft] 30 m [100 ft] 46 m [150 ft]
72 [45] 15 m [50 ft] 23 m [75 ft] 23 m [75 ft] 30 m [100 ft]
Note: Distances are applicable for shadow vehicle speeds up to 25 km/h [15 mph].
Roll-Ahead Distance for Barrier Vehicles
Weight of Barrier
Vehicle (Stationary)
Prevailing
Speed km/h
[mph]
Weight of Impacting Vehicle to be Contained*
2,040 kg
[4,500 lbs]
4,536 kg
[10,000 lbs]
6,804 kg
[15,000 lbs]
10,886 kg
[24,000 lbs]
6,804 kg [15,000 lb]
96-105 [60-65] 8 m [25 ft] 23 m [75 ft] 30 m [100 ft] 46 m [150 ft]
80-88 [50-55] 8 m [25 ft] 15 m [50 ft] 23 m [75 ft] 30 m [100 ft]
72 [45] 8 m [25 ft] 8 m [25 ft] 15 m [50 ft] 23 m [75 ft]
10,886 kg [24,000 lb]
96-105 [60-65] 8 m [25 ft] 15 m [50 ft] 23 m [75 ft] 30 m [100 ft]
80-88 [50-55] 8 m [25 ft] 8 m [25 ft] 15 m [50 ft] 23 m [75 ft]
72 [45] 8 m [25 ft] 8 m [25 ft] 8 m [25 ft] 15 m [50 ft]
*Weights of Typical Vehicles:
Midsize automobile - 1,020 kg [2,250 lb]
Full-size automobile - 1,500 kg [3,500 lb]
Loaded 3/4-ton pickup truck - 2,750 kg [6,000 lb]
Loaded 1-ton cargo truck - 4,500 kg [10,000 lb]
Loaded 4-yard dump truck - 11,000 kg [24,000 lb]
Source: "Use of Truck Mounted Attenuators in Work Zones" by Jack B. Humphreys, P.E. and T.
Darcy Sullivan, P.E., University of Tennessee.