What Nahum seems to be relating is a vision of vehicles moving rapidly at a steady pace on a wide and crowded road which is divided by a wall.  The vehicles are colorful, and or shiny and showy, which he finds handsome to view.  The vehicles have lamps attached and are producing or reflecting beams of light. 

One could draw a different rendering, but not with the same logical progression and only by ignoring the obvious reference to a wide road divided by walls.  Included is the research draft to show how this conclusion was reached.  Strong’s Exhaustive Concordance is the source for definition. 

The verse from the translators: 

Nahum 2:4  The chariots rage in the streets, they jostle one another in the broad roads; they seem like torches, they run like lightning.

A logical rendering:

            Separated by walls, many very colorful and shiny vehicles move at a steady, greedy pace on wide roads. They are very handsome to view, have bright beams of light, and travel swiftly.

A verse breakdown using Strong's Exhaustive Concordance, [numbers], to determine original language and order of appearance:

·   Separated by an outside wall
   [2351] in the streets: chuwts, pronounced khoots or (shortened) chuts {khoots}; from an unused root meaning to sever; properly, separate by a wall, i.e. outside, outdoors:

·   Colorful, shiny, and showy
  [1984] rage: halal, pronounced haw-lal' a primitive root; to be clear (orig. of sound, but usually of color); to shine; hence, to make a show, to boast; and thus to be (clamorously) foolish; to rave; causatively, to celebrate; also to stultify:

·   Many vehicles
   [7393] The chariots: rekeb, pronounced reh'-keb; a vehicle; by implication, a team; by extension, cavalry; by analogy a rider, i.e. the upper millstone:

·   Move deliberately in a direction at a steady even pace
   [8264] they jostle one another: shaqaq, pronounced shaw-kak' a primitive root; to course (like a beast of prey); by implication, to seek greedily.

·   A wide road
   [7339] in the broad roads: rchob, pronounced rekh-obe' or rchowb; a width, i.e. (concretely) avenue or area.

·   Handsome to view
   [4758] they seem: mar'eh, pronounced mar-eh'; a view (the act of seeing); also an appearance (the thing seen), whether (real) a shape (especially if handsome, comeliness; often plural the looks), or (mental) a vision.

·   With lights
   [3940] like torches: lappiyd, pronounced lap-peed' or lappid; from an unused root probably meaning to shine; a flambeau, lamp or flame.

·   Beams of light
   [1300] like lightnings: baraq, pronounced baw-rawk'; lightning; by analogy, a gleam; concretely, a flashing sword.

·   Move swiftly
   [7323] they run: ruwts, pronounced roots, a primitive root; to run (for whatever reason, especially to rush).