Clear Zone Specifications

Table 2-12 from TxDOT Roadway Design Manual
Location
Functional Classification
Design Speed (mph)
Avg. Daily Traffic
Clear Zone Width (ft)
3,4,5
Minimum
Desirable
Rural
Freeways
All
All
30 (16 for ramps)
Rural
Arterial
All
0 - 750
750 - 1500
>1500
10
16
30
16
30
--
Rural
Collector
> 50
All
Use above rural arterial criteria.
Rural
Collector
<45
All
10
--
Rural
Local
All
All
10
--
Suburban
All
All
<8,000
10
6
10
6
Suburban
All
All
8,000 - 12,000
10
6
20
6
Suburban
All
All
12,000 - 16,000
10
6
25
6
Suburban
All
All
>16,000
20
6
30
6
Urban
Freeways
All
All
30 (16 for ramps)
Urban
All (Curbed)
> 50
All
Use above suburban criteria insofar as available border width permits.
Urban
All (Curbed)
< 45
All
4 from curb face
6
Urban
All (Uncurbed)
> 50
All
Use above suburban criteria.
Urban
All (Uncurbed)
< 45
All
10
--
1
 Because of the need for specific placement to assist traffic operations, devices such as traffic signal supports, railroad signal/warning device supports, and controller cabinets are excluded from clear zone requirements. However, these devices should be located as far from the travel lanes as practical. Other non-breakaway devices should be located outside the prescribed clear zone or these devices should be protected with barrier.
2
Average ADT over project life, i.e., 0.5 (present ADT plus future ADT). Use total ADT on two-way roadways and directional ADT on one-way roadways.
3
 Without barrier or other safety treatment of appurtenances.
4
Measured from edge of travel lane for all cut sections and for all fill sections where side slopes are 1V:4H or flatter. Where fill slopes are steeper than 1V:4H it is desirable to provide a 10 ft area free of obstacles beyond the toe of slope.
5
 Desirable, rather than minimum, values should be used where feasible.
6
 Purchase of 5 ft or less of additional right-of-way strictly for satisfying clear zone provisions is not required.