Canberra's light rail project does not require further federal assessment under environmental legislation, the Australian government has ruled.
After assessing planning documents, the Department of Environment says Capital Metro Stage 1 Light Rail Service is unlikely to have a significant impact on environment and heritage matters protected under national environment law.
The documents include noise and environmental assessments.
Consultants have said light rail's operational vibrations at 70km/h were within guideline levels, although these were preliminary findings and more assessment would be needed when track design and the route were finalised.
SLR Consulting Australia said on the basis of available information, the risk of potential adverse noise impact was also considered to be low.
For a maximum train speed of 70km/h, it is considered unlikely that vibration from passing trains would disturb building occupants at distances greater than about 16m from the nearest track centreline.
The consultants said existing traffic noise was already above the light rail noise goals at most measuring locations.
"While Capital Metro would introduce a new noise source to the receptor environments, the potential noise impacts would be limited to whether the light rail noise would be audible above road traffic noise and other localised noise sources," SLR's report said.
Assessment was done on indicative train numbers of 176 during the day and 28 at night.
Residential premises were likely to be the most sensitive receivers on the route, the report said. Warning bells fitted to the light rail vehicles would be distinctive, but their infrequent use would most likely result in negligible noise.
Seven potential traction power substations have been identified along the route. The noise consultants said low-frequency humming and buzzing from electrical substations would mean they would have to be located as far as practical from residential areas. Substations would need to be set back and the noise source enclosed.
Public address systems at stops had the potential to cause annoyance to residents nearby, depending on frequency and time of announcements, the report noted.
"It is recommended the PA systems at stops do not make announcements [other than emergency announcements] during the night time [after 10pm and before 7am].
The Capital Metro Agency said the light rail development, including tracks, overhead wires, depot, substations, utility relocations and revised traffic configurations along the 12-kilometre route, would be completed by one proponent.
The project had potential impact on the endangered golden sun moth and vulnerable striped legless lizard, the report said. The moth's habitat in the north Mitchell grassland area would be disturbed. The lizard and grassland earless dragon were likely to occur in the road verge on the west of Flemington Road and south of Well Station Drive and north Mitchell grassland.
A detailed ecological study would be done and proposed mitigation measures included "pre-clearing and clearing protocols, construction protocols and flora and fauna control measures".
Twelve Aboriginal sites had been identified in Mitchell to the south and west of Flemington Road, comprising stone artefacts scatters, isolated individual stone artefacts and stone artefact raw material resource quarries, including the Red Hill Ochre site. One site was also recorded close to the proposed depot facility, comprising a low-density artefact scatter.
To the west of Flemington Road, 32 sites, comprising mainly artefact scatters and isolated artefacts, have also been documented between Flemington Road and Horse Park Drive and Well Station Drive.
An environmental impact statement would address more detailed assessment of Aboriginal archaeological risks associated with the route, the report said.
Buru Ngunnawal Aboriginal Corporation director Wally Bell said the area was a pathway from Yass to Pialligo valley watercourse and former Capital Hill ceremonial site. The locality still held spiritual connection that had been affected since the establishment of the ACT, he said.