High mast lighting assemblies are specified by pole height and by photometric type. The standard pole heights are 100', 125', 150', and 175'. The photometric types are Types A, B, and S:

Type A and B high mast luminaires have asymmetric optics. This means that instead of creating a round light pattern, they create a long narrow light pattern that works well for lighting a roadway. All Type A or B high mast fixtures on a ring are required to be mounted level and oriented the same direction, typically toward the road. Since they are radially spaced in a ring, the optics must be rotatable to allow aiming.

ype S high mast luminaires have symmetric optics which create a round pattern around the pole. The luminaires must be mounted level, but since they have a round pattern they do not require rotation of the luminaire.

High mast poles are specified by Item 613 and include the pole and anchor bolts. The poles must be fabricated at a plant listed on the MPL for High Mast Illumination Pole Fabrication Plants.

The High Mast Illumination Pole (HMIP) standard contains details and dimensions for TxDOT's standard high mast pole. The standard pole heights are 100', 125', 150', and 175'. The design wind speeds are 80 mph and 100 mph. The wind speed for a location is determined by the standard sheet Wind Velocity and Ice Zones (WV & IZ).

Poles fabricated at an approved fabrication plant and according to the HMIP standards do not require shop drawing submittal.

Item 614 specifies the electrical and mechanical working parts of a high mast lighting assembly. This includes the luminaires, wire rope, rings and supports, obstruction lighting, hoisting assemblies, power drive assemblies, and all other electrical equipment.

The ring and support assemblies must be fabricated at a plant listed on the MPL for High Mast Ring and Support Assembly Fabrication Plants. Luminaires are specified by DMS-11020 or Special Specification 6156. Rings, mechanical, and other electrical parts are specified by DMS-11021 and the HMID standard sheets.

HPS high mast luminaires are specified by DMS-11020. TxDOT typically uses 12 400W HPS luminaires on a ring. HPS luminaires are prequalified on the MPL for Roadway Illumination and Electrical Supplies.

HPS high mast luminaires are not pretested, so they require sampling and testing from the field. Two luminaires must be sampled from each high mast type in the field, unless there are less than 15 luminaires of a certain type. These are sent to a luminaire test lab for testing. TRF oversees the testing contract, receives the test reports, and evaluates whether the luminaires pass or fail to meet specifications.

In most cases LED is now a better choice for high mast lighting than HPS because of LED's maintenance and energy benefits. However HPS is a valid light source and may be used as long as it is available.

LED high mast light fixtures are specified by Special Specification 6156. SS 6156 includes all the other mechanical and electrical parts listed in Item 614, so for a LED high mast assembly, SS 6156 would be used in place of Item 614.

TxDOT LED high mast luminaires are able to use 6 fixtures to light the same area that is lit with 12 TxDOT HPS fixtures. They are designed to be a direct replacement for a 12 fixture HPS ring, and have the same distribution types A, B, and S.

LED high mast luminaires are not currently on an MPL and require submittals for each project. However TRF has reviewed several brands and may be contacted for assistance in evaluating whether a submitted luminaire meets specifications.

LED high mast luminaires do not currently have sampling and testing requirements.

All high mast mechanical and electrical materials required for a complete high mast lighting assembly that are not specified elsewhere are specified by DMS-11021. This includes rings, ring supports, obstruction lights, hoisting assemblies, power drive assemblies, electrical equipment, power cord, enclosures, and other materials detailed in the HMID standards.

High mast illumination assembly kits are prequalified under Item 614 on the MPL for Roadway Illumination and Electrical Supplies.

The High Mast Illumination Details (HMID) standard sheets contain the specifications and details for the structural, mechanical, and electrical parts of TxDOT's standard high mast lighting assemblies. It includes details for the ring, ring supports, lowering system, and other mechanical and electrical systems needed to construct a complete assembly. The HMID sheets should be included in the plans whenever high mast lighting assemblies are used on a project.

A high mast illumination pole foundation is necessary for all high mast poles. They are typically specified by 0416 XXXX DRILL SHAFT (HIGH MAST POLE) (XX IN), where the diameter XX can range from 54 in. to 66 in. The foundation's concrete and steel is included in Item 416, and the anchor bolts are included in Item 613. The riprap pad around the foundation is typically specified by 0432 6001 RIPRAP (CONC)(4 IN).

High mast illumination pole foundations are measured by the linear foot of drill shaft depth.

The High Mast Illumination Foundation Details (HMIF) standard sheets contain the specifications and details for TxDOT's standard high mast foundations. They include details for the foundation, and design information for the drill shaft depth, diameter, and anchor bolts. The HMIF sheets should be included in the plans whenever high mast lighting assemblies are used on a project.