🧹 Chore: Magic Numbers in Bus Speed Computations

[DavidOry]

The section of code that computes bus speeds from automobile speeds is ripe with magic numbers. These need to refer to either to fixed definitions defined in a data model or schema, or refer to dictionaries defined in the control files.

tm2py/tm2py/components/network/transit/transit_network.py

Lines 186 to 211 in 36b8066

	if auto_time > 0:
	# https://github.com/BayAreaMetro/travel-model-one/blob/master/model-files/scripts/skims/PrepHwyNet.job#L106
	tran_speed = 60 * link_length/auto_time
	if (facility_type<=4 or facility_type==8) and (tran_speed<6):
	tran_speed = 6
	_transit_link_dict[_link_id]["@trantime"] = 60 * link_length/tran_speed
	elif (tran_speed<3):
	tran_speed = 3
	_transit_link_dict[_link_id]["@trantime"] = 60 * link_length/tran_speed
	else:
	_transit_link_dict[_link_id]["@trantime"] = auto_time
	# data1 is the auto time used in Mixed-Mode transit assigment
	_transit_link_dict[_link_id].data1 = (_transit_link_dict[_link_id]["@trantime"] +
	60*sov_toll/self.config.value_of_time)
	# bus time calculation
	if facility_type in [1,2,3,8]:
	delayfactor = 0.0
	else:
	if area_type in [0,1]:
	delayfactor = 2.46
	elif area_type in [2,3]:
	delayfactor = 1.74
	elif area_type==4:
	delayfactor = 1.14
	else:
	delayfactor = 0.08

Progress:

• Sufficiently defined
• Approach decided
• Implemented

Considerations

Ideally, things like facility type would be defined in code in one and only one place. These references could then be imported and use in this code. In the short-term, moving the magic numbers to a config file would be an improvement.

cc @gregerhardt @lmz